Abstract
An integrative taxonomic study combining morphological and molecular data revealed two new species of giant pill-millipedes of the genus Zephronia Gray, 1832: Zephronia tamarindina Wilaisorn & Srisonchai, sp. nov. and Zephronia triforma Wilaisorn & Srisonchai, sp. nov., both endemic to provinces in the upper central region of Thailand. In addition, Zephronia dawydoffi Attems, 1953 and Zephronia laotica Wesener, 2019 are recorded from Thailand for the first time. The new species exhibit distinctive colouration patterns, and scanning electron microscopy revealed unique morphological characters for each taxon. Analysis of the 658 bp DNA barcoding region of the mitochondrial COI gene showed interspecific genetic distances ranging from 8.68–21.92% for Z. dawydoffi, 12.79–22.98% for Z. laotica, 10.81–22.07% for Z. tamarindinasp. nov., and 10.81–22.83% for Z. triformasp. nov., in comparison with closely related species from Thailand, Vietnam, Laos, and Cambodia. Phylogenetic analyses placed all four species within the Zephronia s.s. clade, characterised by the Tömösváry’s organ located outside the antennal groove. However, relationships among other clades remained unresolved due to interspersion with species of Cryxus Leach, 1814, Prionobelum Verhoeff, 1924, and Sphaerobelum Verhoeff, 1924. Zephronia was recovered as non-monophyletic, indicating that the current generic limits within Zephroniinae require reassessment using multi-locus data. These results expand our understanding of giant pill-millipede diversity and highlight the upper central Thai region and Southeast Asia more broadly as a significant biodiversity hotspot.
Key words: Biodiversity, DNA barcoding, Myriapoda , Southeast Asia, taxonomy
Introduction
The order Sphaerotheriida with their family Zephroniidae are notable for their heavily sclerotised exoskeleton and remarkable ability to roll into a ball-like shape when threatened (Enghoff et al. 2015). The genus Zephronia Gray, 1832 is among the most species-rich groups of giant pill-millipedes. With more than 50 described species distributed across Cambodia, China (including Hong Kong), India, Indonesia, Laos, Malaysia, Myanmar, Nepal, Singapore, Thailand, and Vietnam, Zephronia exemplifies the biological diversity and regional richness of Southeast Asia (Wesener 2016; Semenyuk et al. 2018; Wesener 2019; Semenyuk et al. 2020; Likhitrakarn et al. 2021; Rosenmejer et al. 2021; Srisonchai et al. 2021, 2024; Srimongkol et al. 2026). Morphologically diverse and ecologically specialised, Zephronia forms an integral part of the region’s diplopod fauna. However, despite recent taxonomic revisions and field surveys, the genus remains poorly documented in several biogeographically important areas, particularly in mainland Southeast Asia, including Thailand.
Thailand, situated within the Indo-Burma biodiversity hotspot, harbours a remarkable diversity of millipedes (Diplopoda), with approximately 287 recorded species, a continuously growing number as new discoveries are made (Likhitrakarn et al. 2023; Srisonchai et al. 2023; Donworth and Wesener 2024; Srisonchai et al. 2024; Srikampha et al. 2025; Srimongkol et al. 2026). Most Thai millipede species have been recorded from the central area near the Chao Phraya River Basin, which is considered a major centre of biodiversity in Thailand. Among Thai giant pill-millipedes, only the family Zephroniidae has been documented, represented by three genera: Sphaerobelum Verhoeff, 1924, Prionobelum Verhoeff, 1924, and Zephronia Gray, 1832 (Srisonchai et al. 2023; Donworth and Wesener 2024).
Recent targeted surveys have discovered many new species of the genus Zephronia. Since 2021, the interest in Thai giant pill-millipedes has surged, leading to the recognition of up to 14 Zephronia species, viz., Z. chantaburiensis Srisonchai & Wesener, 2024, Z. chrysomallos Bhansali & Wesener, 2022, Z. enghoffi Srisonchai & Likhitrakarn, 2021, Z. erawani Bhansali & Wesener, 2022, Z. golovatchi Srisonchai & Likhitrakarn, 2021, Z. lannaensis Likhitrakarn & Golovatch, 2021, Z. macula Srisonchai & Wesener, 2024, Z. ovalis Gray, 1832, Z. panhai Srisonchai & Likhitrakarn, 2021, Z. phrain Likhitrakarn & Golovatch, 2021, Z. siamensis Hirst, 1907, Z. sukhothaiensis Srimongkol & Srisonchai, 2026, Z. tratensis Srimongkol & Srisonchai, 2026, and Z. viridisoma Rosenmejer & Wesener, 2021. This growing list underscores the remarkable morphological diversity of Zephronia in Thailand. However, as with other genera in the Zephroniidae, the taxonomic research on Zephronia remains challenging due to limited genetic data and unclear evolutionary relationships (Wesener 2019).
DNA barcoding, based on a fragment of the mitochondrial cytochrome c oxidase subunit I (COI) gene, has become a powerful molecular tool for millipede species identification. This method enables the rapid and reliable detection of genetic divergence, even among morphologically similar taxa, which is particularly valuable for groups with cryptic species or subtle diagnostic traits. When combined with morphological data, DNA barcoding provides a robust framework for resolving taxonomic uncertainties, verifying species boundaries, and uncovering hidden diversity. Such integrative approaches have proven especially effective for species delimitation for the giant pill-millipede genus Zephronia (Wesener 2019; Rosenmejer et al. 2021; Bhansali and Wesener 2022; Zhao et al. 2022; Srisonchai et al. 2024; Srimongkol et al. 2026).
Continuous field surveys and taxonomic workshops have resulted in the accumulation of extensive material over time, from which the specimens examined in this study were obtained. Examination of four morphologically distinct groups of giant pill-millipedes collected during field surveys in 2022–2024 revealed both previously undescribed species and new country records. These findings highlight the rich but still incompletely documented diversity of Zephronia in Thailand, particularly in underexplored habitats where endemism is likely high. In this study, we formally describe two new Zephronia species and report the first records of Z. dawydoffi Attems, 1953 and Z. laotica Wesener, 2019 in the country. To ensure accurate identification and resolve potential taxonomic ambiguities, we employed an integrative taxonomic approach, combining detailed morphological examination with molecular analysis based on mitochondrial COI sequences.
Materials and methods
Specimen collections
The sampling was conducted across the upper central and northeastern regions of Thailand, as well as adjacent areas between 2022 and 2024. All specimens were collected by hand, searching at ground level, beneath leaf litter, and within decomposed logs across a variety of habitats, including agricultural fields, plantation forests, and limestone mountains. Live specimens were photographed in situ using a Canon 90D digital camera equipped with a Canon EF 100 mm f/2.8 Macro USM lens. Specimens were euthanised in accordance following the guidelines of the American Veterinary Medical Association (2020). The research protocol was approved by the Institutional Animal Care and Use Committee of Khon Kaen University (No. IACUC-KKU-137/67). After photography, all individuals were preserved in 95% ethanol. Geographic coordinates were recorded on site for each collection locality.
Maps
The map was generated using a background image from Simplemappr (Shorthouse 2010) and subsequently edited in Adobe Photoshop 2025.
Morphological identifications and descriptions
A total of 290 specimens were examined under a stereomicroscope. Species identification was based on morphological characters and comparisons with descriptions from the previous literature, as well as with type specimens of other Thai congeners. Morphological terminology and descriptive formats followed those used by Golovatch et al. (2012), Wesener (2019), Semenyuk et al. (2018), and Srisonchai et al. (2024) for morphological descriptions.
Type specimens, including holotypes and paratypes, were deposited in the following institutions: Chulalongkorn University Museum of Zoology, Thailand (CUMZ), Khon Kaen University Museum of Zoology, Thailand (invertebrate collections) (MZKKU), Natural History Museum of Denmark, Denmark (NHMD), Natural History Museum, United Kingdom (NHMUK), Naturhistorisches Museum Wien, Austria (NHMW) and Zoological Research Museum Koenig, Germany (ZFMK).
Because the present study focuses on the description and redescription of four species rather than a comprehensive revision of the genus Zephronia, no general description of the genus is provided. Instead, each species is described separately in full to facilitate direct comparisons and to ensure clarity in species delimitations. Such a format is commonly adopted in taxonomic works dealing with a limited number of new species, particularly when the primary objective is species diagnoses and identification rather than a generic revision.
List of abbreviations
3it 3-combed inner tooth of mandible,
bu bursa of vulva,
co condylus of mandible,
Cp central pad of gnathochilarium,
cr-t crenulated teeth on telopods,
ct central tooth,
cx coxa,
et external tooth of epipharynx,
Et external tooth of mandibular gnathal lobe,
fe femur,
Ia inner area of mandible,
il incisura lateralis of the head,
ip inner palpi of gnathochilarium,
ll lamellae lingulales of gnathochilarium,
me mentum of gnathochilarium,
ml membranous lobe,
mp molar plate of mandible,
Mp membranous process
op operculum of vulva,
pl pectinate lamellae of mandible,
po postfemur,
pre prefemur,
rdg femoral ridge,
rsp row of spines,
sc sensory cone,
scl-s sclerotised spots,
st stipites of gnathochilarium,
st-pl stigmatic plate,
syn-cx syncoxite,
ta tarsus,
ti tibia.
Scanning electron microscopy (SEM)
The specimens were examined and dissected under a stereo microscope. Morphological structures were dried in the desiccator for 24 hours, mounted on aluminium stubs, and coated with gold. Samples were then photographed under a high vacuum in a JEOL JSM-5410 LV scanning electron microscope at the Faculty of Science, Khon Kaen University. All figures were subsequently assembled and refined in Adobe Photoshop 2025.
DNA extraction and PCR amplifications
The genomic DNA was extracted from 27 specimens, comprising four and eight specimens of the two new species, ten specimens of Z. dawydoffi, and foive specimens of Z. laotica. Extractions were performed from the leg tissue using proteinase K digestion and following the manufacturer’s instructions of Vivantis GF-1 Nucleic Acid Extraction Kits. PCR amplification of the 658 bp barcoding region of the mitochondrial cytochrome c oxidase subunit I (COI) gene using the universal primers — LCO-1490 (5’-GGT CAA CAA ATC ATA AAG ATA TTG G-3’) and HCO-2198 (5’-TAA ACT TCA GGG TGA CCA AAA AAT CA-3’) (Folmer et al. 1994). The thermal cycling program began with one cycle at 94 °C for 3 min; followed by 35 cycles of denaturation at 94 °C for 30 sec, annealing at 45 or 47 °C for 40 sec, and extension at 72 °C for 1 min, and a final extension step at 72 °C for 5 min. The PCR success was checked using 1.5% agarose gel electrophoresis and then observed under UV transillumination. The PCR products were purified and sequenced, using the same primers as those used for PCR amplification, at ATGC Co., Ltd. (Thailand).
DNA alignment and COI barcoding tree reconstruction
A total of 124 sequences were analysed, including 27 sequences generated in this study and 97 sequences retrieved from public databases representing all recorded Zephronia species. Outgroups included Arthrosphaera brandtii (Humbert, 1865), Cryxus ovalis (Linnaeus, 1758), Epicyliosoma sp., Glomeris marginata (Villers, 1789), Prionobelum spp., Sphaerobelum spp., and Sphaeromimus splendidus Wesener & Sierwald, 2005. The newly generated sequences were then deposited in GenBank (Table 1).
Table 1.
List of species analysed in this study with GenBank accession numbers.
| Species | COI accession number | Voucher code | Locality | Reference | |
|---|---|---|---|---|---|
| Ingroups | |||||
| 1 | Zephronia chantaburiensis Srisonchai & Wesener, 2024 | PP754582 | CUMZ (M47) | Thailand, Chantaburi Province, Tha Mai District, Wat Khao Sukim | Srisonchai et al. 2024 |
| 2 | Zephronia chantaburiensis Srisonchai & Wesener, 2024 | PP754583 | CUMZ (M48) | Thailand, Chantaburi Province, Tha Mai District, Wat Khao Sukim | Srisonchai et al. 2024 |
| 3 | Zephronia chrysomallos Bhansali & Wesener, 2022 | OM509649 | ZFMK MYR8826 | Thailand, Kanchanaburi Province, Sai Yok District, Sai Yok Noi Waterfall | Bhansali and Wesener 2022 |
| 4 | Zephronia dawydoffi Attems, 1953 | MK330971 | ZFMK Myr4504 | N/A | Wesener 2019 |
| 5 | Zephronia dawydoffi Attems, 1953 | PX737475 | MZKKU (BRM06) | Thailand, Buri Ram Province, Khu Mueang District, Dong Kheng rubber plantation | This study |
| 6 | Zephronia dawydoffi Attems, 1953 | PX737476 | MZKKU (BRM10) | Thailand, Buri Ram Province, Khu Mueang District, Dong Kheng rubber plantation | This study |
| 7 | Zephronia dawydoffi Attems, 1953 | PX737477 | MZKKU (BRM17) | Thailand, Buri Ram Province, Khu Mueang District, Non Somboon Monastery | This study |
| 8 | Zephronia dawydoffi Attems, 1953 | PX737478 | MZKKU (BRM24) | Thailand, Buri Ram Province, Khu Mueang District, Non Somboon Monastery | This study |
| 9 | Zephronia dawydoffi Attems, 1953 | PX737479 | MZKKU (DBR01) | Thailand, Buri Ram Province, Mueang District, Khao Kradong | This study |
| 10 | Zephronia dawydoffi Attems, 1953 | PX737480 | MZKKU (DBR02) | Thailand, Buri Ram Province, Mueang District, Khao Kradong | This study |
| 11 | Zephronia dawydoffi Attems, 1953 | PX737481 | MZKKU (DBR04) | Thailand, Buri Ram Province, Mueang District, Ban Khok Ta Sing Waterfall | This study |
| 12 | Zephronia dawydoffi Attems, 1953 | PX737482 | MZKKU (DBR06) | Thailand, Buri Ram Province, Mueang District, Ban Khok Ta Sing Waterfall | This study |
| 13 | Zephronia dawydoffi Attems, 1953 | PX737483 | MZKKU (KKN12) | Thailand, Khon Kaen Province, Mueang District, Thung Setthi Temple | This study |
| 14 | Zephronia dawydoffi Attems, 1953 | PX737484 | MZKKU (KKN20) | Thailand, Khon Kaen Province, Mueang District, Thung Setthi Temple | This study |
| 15 | Zephronia erawani Bhansali & Wesener, 2022 | OM509650 | NHMD K56x9 | Thailand, Kanchanaburi Province, Si Sawat District, 50 km W of Kanchanaburi, Erawan Waterfall | Bhansali and Wesener 2022 |
| 16 | Zephronia golovatchi Srisonchai, Sutcharit & Likhitrakarn, 2021 | OM509646 | ZFMK MYR6262 | Thailand, Nakhon Ratchasima Province, Pak Chong District | Bhansali and Wesener 2022 |
| 17 | Zephronia golovatchi Srisonchai, Sutcharit & Likhitrakarn, 2021 | OM509647 | ZFMK K53 | Thailand, Nakhon Nayok Province, Khao Yai National Park | Bhansali and Wesener 2022 |
| 18 | Zephronia hui Liu & Wesener, 2022 | OP339790 | SCAU YGM03 | China, Guizhou, Tongren City, Jiangkou County, Taiping Town, Yamugou Scenic Area | Zhao et al. 2022 |
| 19 | Zephronia lannaensis Likhitrakarn & Golovatch, 2021 | OM509629 | ZFMK MYR3498 | Thailand, Chiangmai Province, Mueang District, Doi Suthep | Bhansali and Wesener 2022 |
| 20 | Zephronia lannaensis Likhitrakarn & Golovatch, 2021 | OM509630 | ZFMK MYR3501 | Thailand, Chiangmai Province, Mae Rim District, Traidhos School Campus | Bhansali and Wesener 2022 |
| 21 | Zephronia lannaensis Likhitrakarn & Golovatch, 2021 | OM509631 | ZFMK MYR4911 | Thailand, Chiangmai Province, Mae Rim District, Mae Sa Valley | Bhansali and Wesener 2022 |
| 22 | Zephronia lannaensis Likhitrakarn & Golovatch, 2021 | OM509632 | NHMD K57B | Thailand, Chiangmai Province, Mueang District, Doi Suthep, Me Sa Waterfall | Bhansali and Wesener 2022 |
| 23 | Zephronia lannaensis Likhitrakarn & Golovatch, 2021 | OM509633 | MHNG 3B | Thailand, Chiangmai Province, Mueang District, Doi Suthep | Bhansali and Wesener 2022 |
| 24 | Zephronia laotica Wesener, 2019 | MK330977 | ZFMK Myr3502 | Laos, Champasak Province, east of Mekong, Garden of Erawan Riverside Hotel | Wesener 2019 |
| 25 | Zephronia laotica Wesener, 2019 | PX737485 | MZKKU (SSK01) | Thailand, Si Sa Ket Province, Khun Han District, Mae Lamoon Durian plantation | This study |
| 26 | Zephronia laotica Wesener, 2019 | PX737486 | MZKKU (SSK03) | Thailand, Si Sa Ket Province, Khun Han District, Mae Lamoon Durian plantation | This study |
| 27 | Zephronia laotica Wesener, 2019 | PX737487 | MZKKU (SSK14) | Thailand, Si Sa Ket Province, Khun Han District, Kantrom Tai Temple | This study |
| 28 | Zephronia laotica Wesener, 2019 | PX737488 | MZKKU (SSK18) | Thailand, Si Sa Ket Province, Khun Han District, Kantrom Tai Temple | This study |
| 29 | Zephronia laotica Wesener, 2019 | PX737489 | MZKKU (SSK25) | Thailand, Si Sa Ket Province, Khun Han District, Ta Nuan Rubber plantation | This study |
| 30 | Zephronia macula Srisonchai & Wesener, 2024 | PP754589 | CUMZ (M54) | Thailand, Sra Kaeo Province, Mueang Sra Kaeo District, Wat Tham Khao Maka | Srisonchai et al. 2024 |
| 31 | Zephronia macula Srisonchai & Wesener, 2024 | PP754590 | CUMZ (M55) | Thailand, Sra Kaeo Province, Mueang Sra Kaeo District, Wat Tham Khao Maka | Srisonchai et al. 2024 |
| 32 | Zephronia macula Srisonchai & Wesener, 2024 | PP754585 | CUMZ- MYR 0015 (M418) | Thailand, Chantaburi Province, Khlung District, Thaeo Khlong Khlung Monastery | Srisonchai et al. 2024 |
| 33 | Zephronia macula Srisonchai & Wesener, 2024 | PP754587 | CUMZ- MYR 0015 (M422) | Thailand, Chantaburi Province, Tha Mai District, Wat Khao Sukim | Srisonchai et al. 2024 |
| 34 | Zephronia macula Srisonchai & Wesener, 2024 | PX526095 | MZKKU (M400) | Thailand, Chantaburi Province, Tha Mai District, Wat Khao Sukim | Srimongkol et al. 2026 |
| 35 | Zephronia macula Srisonchai & Wesener, 2024 | PX526097 | MZKKU (M437) | Thailand, Chachoengsao Province, Phanom Sarakham District, Wat Khao Hin Sorn | Srimongkol et al. 2026 |
| 36 | Zephronia macula Srisonchai & Wesener, 2024 | PX526098 | MZKKU (M438) | Thailand, Rayong Province, Khao Chamao District, Wat Tham Suwan Phupha | Srimongkol et al. 2026 |
| 37 | Zephronia macula Srisonchai & Wesener, 2024 | PX526100 | MZKKU (M457) | Thailand, Sa Kaeo Province, Khao Chakan District, Wat Tham Khao Chan | Srimongkol et al. 2026 |
| 38 | Zephronia medongensis Zhao & Liu, 2022 | OP339793 | SCAU XZ01 | China, Xizang Autonomous Region, Medog County | Zhao et al. 2022 |
| 39 | Zephronia ovalis Gray, 1832 | JX486068 | ZFMK Myr 0832 | Vietnam, Dong Nai Province, Cat Tien National Park | Golovatch et al. 2012 |
| 40 | Zephronia ovalis Gray, 1832 | PX526103 | MZKKU (M180) | Thailand, Si Sa Ket Province, Khunhan District, Huai Chan Waterfall | Srimongkol et al. 2026 |
| 41 | Zephronia ovalis Gray, 1832 | PX526104 | MZKKU (M181) | Thailand, Si Sa Ket Province, Khunhan District, Huai Chan Waterfall | Srimongkol et al. 2026 |
| 42 | Zephronia ovalis Gray, 1832 | PX526105 | MZKKU (M204) | Thailand, Si Sa Ket Province, Khunhan District, Huai Chan Waterfall | Srimongkol et al. 2026 |
| 43 | Zephronia panhai Srisonchai, Sutcharit & Likhitrakarn, 2021 | OM509643 | ZFMK MYR 8118 | Thailand, Ratchaburi Province, Ratchaburi-Photharam Districts | Bhansali and Wesener 2022 |
| 44 | Zephronia panhai Srisonchai, Sutcharit & Likhitrakarn, 2021 | OM509644 | MHNG 3A | Thailand, Ratchaburi Province, Chom Bueang District, Tham Kao Bin Forest Park | Bhansali and Wesener 2022 |
| 45 | Zephronia panhai Srisonchai, Sutcharit & Likhitrakarn, 2021 | OM509645 | ZFMK MYR 8116 | Thailand, Ratchaburi Province, Ratchaburi-Photharam Districts | Bhansali and Wesener 2022 |
| 46 | Zephronia phrain Likhitrakarn & Golovatch, 2021 | OM509634 | ZFMK MYR 3499 | Thailand, Chiang Mai Province, Chiang Dao District, Padeng Lodge | Bhansali and Wesener 2022 |
| 47 | Zephronia phrain Likhitrakarn & Golovatch, 2021 | OM509635 | MYR3500 | Thailand, Chiangmai Province, Mueang District, Doi Suthep | Bhansali and Wesener 2022 |
| 48 | Zephronia phrain Likhitrakarn & Golovatch, 2021 | OM509636 | SMF | Thailand, Chiang Mai Province, Chiang Dao District, Tham Houay Luk | Bhansali and Wesener 2022 |
| 49 | Zephronia phrain Likhitrakarn & Golovatch, 2021 | OM509637 | SMF | Thailand, Chiang Mai Province, Chiang Dao District, Doi Chiang Dao, Ma Lee’s Resort | Bhansali and Wesener 2022 |
| 50 | Zephronia phrain Likhitrakarn & Golovatch, 2021 | OM509638 | SMF | Thailand, Chiang Mai Province, Chai Prakan District, Tham Ngam | Bhansali and Wesener 2022 |
| 51 | Zephronia phrain Likhitrakarn & Golovatch, 2021 | OM509639 | ZFMK MYR 4907 | Thailand, Chiang Mai Province, Chiang Dao | Bhansali and Wesener 2022 |
| 52 | Zephronia phrain Likhitrakarn & Golovatch, 2021 | OM509640 | MHNG 5G | Thailand, Lamphun Province, Mae Tha District, Doi Khuntan National Park | Bhansali and Wesener 2022 |
| 53 | Zephronia phrain Likhitrakarn & Golovatch, 2021 | OM509641 | MHNG 5I | Thailand, Chiang Mai Province, Chiang Dao District, Doi Chiang Dao | Bhansali and Wesener 2022 |
| 54 | Zephronia phrain Likhitrakarn & Golovatch, 2021 | OM509642 | NHMD K35 | Thailand, Chiang Mai Province, Ban Musue | Bhansali and Wesener 2022 |
| 55 | Zephronia siamensis Hirst, 1907 (unverified) | JX486067.2 | FMNH-INS-72669 | Thailand, Chonburi Province, Sichang District, Koh Sichang | Golovatch et al. 2012 |
| 56 | Zephronia siamensis Hirst, 1907 | OR530089 | CUMZ | Thailand, Chonburi Province, Sichang District, Koh Sichang | Srisonchai et al. 2023 |
| 57 | Zephronia siamensis Hirst, 1907 | PP754592 | CUMZ (M455) | Thailand, Chachoengsao Province, Phanom Sarakham District, Wat Khao Hin Sorn | Srisonchai et al. 2024 |
| 58 | Zephronia siamensis Hirst, 1907 | PP754591 | CUMZ (D397) | Thailand, Srakaeo Province, Khao Chakan District, Wat Tham Khao Chan | Srisonchai et al. 2024 |
| 59 | Zephronia sp. (K45 Aow Noi Temple) | MW898741 | NHMD K55 | Thailand, Prachuap Kiri Khan Province, Mueang District, Aow Noi Temple | Rosenmejer et al. 2021 |
| 60 | Zephronia sp. (Aow Noi Temple) | MW898742 | ZFMK MYR 8787 | Thailand, Prachuap Kiri Khan Province, Mueang District, Aow Noi Temple | Rosenmejer et al. 2021 |
| 61 | Zephronia sukhothaiensis Srimongkol & Srisonchai, 2026 | PX526107 | MZKKU (L43) | Thailand, Sukhothai Province, Ban Dan Lan Hoi District, Wat Khao Fang | Srimongkol et al. 2026 |
| 62 | Zephronia sukhothaiensis Srimongkol & Srisonchai, 2026 | PX526108 | MZKKU (M323) | Thailand, Sukhothai Province, Ban Dan Lan Hoi District, Wat Khao Fang | Srimongkol et al. 2026 |
| 63 | Zephronia sukhothaiensis Srimongkol & Srisonchai, 2026 | PX526110 | MZKKU (M325) | Thailand, Sukhothai Province, Ban Dan Lan Hoi District, Wat Khao Fang | Srimongkol et al. 2026 |
| 64 | Zephronia tamarindina sp. nov. | PX737490 | MZKKU (L83) | Thailand, Phetchabun Province, Bueng Sam Phan District, Nimit Sat Cha Dhum Temple | This study |
| 65 | Zephronia tamarindina sp. nov. | PX737491 | MZKKU (L84) | Thailand, Phetchabun Province, Bueng Sam Phan District, Nimit Sat Cha Dhum Temple | This study |
| 66 | Zephronia tamarindina sp. nov. | PX737492 | MZKKU (UPNB01) | Thailand, Phetchabun Province, Bueng Sam Phan District, Nimit Sat Cha Dhum Temple | This study |
| 67 | Zephronia tamarindina sp. nov. | PX737493 | MZKKU (UPNB02) | Thailand, Phetchabun Province, Bueng Sam Phan District, Nimit Sat Cha Dhum Temple | This study |
| 68 | Zephronia tratensis Srimongkol & Srisonchai, 2026 | PX526112 | MZKKU (M415) | Thailand, Trat Province, Mueang District, Khao Khun Tham Monastery | Srimongkol et al. 2026 |
| 69 | Zephronia tratensis Srimongkol & Srisonchai, 2026 | PX526113 | MZKKU (M416) | Thailand, Trat Province, Mueang District, Khao Khun Tham Monastery | Srimongkol et al. 2026 |
| 70 | Zephronia triforma sp. nov. | PX737494 | MZKKU (L60) | Thailand, Nakhon Sawan Province, Takhli District, Buddhawajana Dhamma Retreat | This study |
| 71 | Zephronia triforma sp. nov. | PX737495 | MZKKU (L61) | Thailand, Nakhon Sawan Province, Takhli District, Buddhawajana Dhamma Retreat | This study |
| 72 | Zephronia triforma sp. nov. | PX737498 | MZKKU (UNSN01) | Thailand, Nakhon Sawan Province, Takhli District, Buddhawajana Dhamma Retreat | This study |
| 73 | Zephronia triforma sp. nov. | PX737499 | MZKKU (UNSN02) | Thailand, Nakhon Sawan Province, Takhli District, Buddhawajana Dhamma Retreat | This study |
| 74 | Zephronia triforma sp. nov. | PX737496 | MZKKU (L227) | Thailand, Phitsanulok Province, Wat Bot District, Ban Nam Kob | This study |
| 75 | Zephronia triforma sp. nov. | PX737497 | MZKKU (L229) | Thailand, Phitsanulok Province, Wat Bot District, Ban Nam Kob | This study |
| 76 | Zephronia triforma sp. nov. | PX737500 | MZKKU (UPLK07) | Thailand, Phitsanulok Province, Wat Bot District, Khao Bo Ma Viewpoint | This study |
| 77 | Zephronia triforma sp. nov. | PX737501 | MZKKU (UPLK12) | Thailand, Phitsanulok Province, Wat Bot District, Khao Bo Ma Viewpoint | This study |
| 78 | Zephronia viridisoma Rosenmejer & Wesener, 2021 | MW898739 | NHMD 621695 | Thailand, Nakhon Si Thammarat Province, Sichon District, Khao Lark Waterfall | Rosenmejer et al. 2021 |
| 79 | Zephronia zhouae Zhao & Liu, 2022 | OP339794 | SCAU YN02 | China, Yunnan Province, Diqing Tibetan Autonomous Prefecture, Weixi County, Laowo Village | Rosenmejer et al. 2021 |
| Outgroups | |||||
| 80 | S. aesculus Rosenmejer & Wesener, 2021 | MW898737 | NHMD 621693 | Thailand, Phuket Province, Kathu District, Forest | Rosenmejer et al. 2021 |
| 81 | S. cf. aesculus Rosenmejer & Wesener, 2021 | MW898738 | NHMD 621694 | Thailand, Nakhon Si Thammarat Province, Khao Luang NP | Rosenmejer et al. 2021 |
| 82 | S. benquii Liu & Wesener, 2022 | OP339792 | SCAU MMY01 | China, Guizhou, Tongren City, Jiangkou County, Guanhe Town, Guanhe Village, Maomaoyan | Zhao et al. 2022 |
| 83 | S. bolavensis Wesener, 2019 | MK330982 | MHNG LT-10/24 | Laos, Champasak Province, Bolaven Plateau, 3 km S of Ban Nong Luang, Tad Kameud | Wesener 2019 |
| 84 | S. denticulatum Wesener, 2019 | MK330984 | MHNG LT-10/12 | Laos, Oudomxai Province, ca 3 km E of Tad Lak 11, SE of Oudomxai city | Wesener 2019 |
| 85 | S. huzhengkuni Zhao, Yu & Liu, 2020 | MT657327 | SCAU SP02 | China, Guizhou Province, Tongren City, Fanjingshan National Nature Reserve | Zhao et al. 2020 |
| 86 | S. huzhengkuni Zhao, Yu & Liu, 2020 | MT657328 | SCAU SP03 | China, Guizhou Province, Tongren City, Fanjingshan National Nature Reserve | Zhao et al. 2020 |
| 87 | S. lachneeis Wesener, 2019 | MK330983 | MHNG LT-10/12 | Laos, Oudomxai Province, ca 3 km E of Tad Lak 11, SE of Oudomxai city | Wesener 2019 |
| 88 | S. laoticum Wesener, 2019 | MK330975 | SMF | Laos, Vientiane Province, Vang Vieng | Wesener 2019 |
| 89 | S. meridionalis Bhansali & Wesener, 2022 | OM509648 | MHNG 4B-2 | Thailand, Yala Province, Bannang Sata District, Bang Lang National Park, near Than To Waterfall | Bhansali and Wesener 2022 |
| 90 | S. nigrum Wesener, 2019 | MK330976 | SMF | Laos, Champasak Province, Muang Bachieng, Ban Lak 35, Tad Etu | Wesener 2019 |
| 91 | S. nonghinensis Srikampha & Srisonchai, 2025 | PQ838982 | MZKKU (A35) | Thailand, Loei Province, Nong Hin District, Suan Hin Pha Ngam (Hin Pha Ngam Park) | Srikampha et al. 2025 |
| 92 | S. nonghinensis Srikampha & Srisonchai, 2025 | PQ838983 | MZKKU (A36) | Thailand, Loei Province, Nong Hin District, Suan Hin Pha Ngam (Hin Pha Ngam Park) | Srikampha et al. 2025 |
| 93 | S. nonghinensis Srikampha & Srisonchai, 2025 | PQ838984 | MZKKU (E28) | Thailand, Loei Province, Nong Hin District, Suan Hin Pha Ngam (Hin Pha Ngam Park) | Srikampha et al. 2025 |
| 94 | S. nonghinensis Srikampha & Srisonchai, 2025 | PQ838986 | MZKKU (M237) | Thailand, Loei Province, Nong Hin District, Suan Hin Pha Ngam (Hin Pha Ngam Park) | Srikampha et al. 2025 |
| 95 | S. onyx Srikampha & Srisonchai, 2025 | PQ838987 | MZKKU (M211) | Thailand, Buang Kan Province, Seka District, Wat Tham Chum Chang (Nam Yaad Clift) | Srikampha et al. 2025 |
| 96 | S. peterjaegeri Wesener, 2019 | MK330972 | SMF SD553 | Laos, Luang Prabang Province, SE Luang Prabang, Nam Khan, Ban Pak Bak, Houay Kho | Wesener 2019 |
| 97 | S. petramurum Srikampha & Srisonchai, 2025 | PQ838989 | MZKKU (E5) | Thailand, Khon Kaen Province, Phu Pha Man District, Ban Khao Wong | Srikampha et al. 2025 |
| 98 | S. petramurum Srikampha & Srisonchai, 2025 | PQ838991 | MZKKU (L128) | Thailand, Khon Kaen Province, Phu Pha Man District, Ban Khao Wong | Srikampha et al. 2025 |
| 99 | S. petramurum Srikampha & Srisonchai, 2025 | PQ838992 | MZKKU (L6) | Thailand, Chaiyaphum Province, Khon San District, Mortagek Monastery | Srikampha et al. 2025 |
| 100 | S. petramurum Srikampha & Srisonchai, 2025 | PQ838993 | MZKKU (M217) | Thailand, Khon Kaen Province, Phu Pha Man District, Ban Khao Wong | Srikampha et al. 2025 |
| 101 | S. phouloei Wesener, 2019 | MK330974 | ZMUC00040257 | Laos, Houaphan Province, Phou Loei | Wesener 2019 |
| 102 | S. schwendingeri Wesener, 2019 | MK330978 | MHNG LT-10/03 | Laos, Vientiane Province, trail to Tham Pou Kham, W. of Vang Vieng | Wesener 2019 |
| 103 | S. schwendingeri Wesener, 2019 | MK330981 | SMF | Laos, Vientiane Province, Vang Vieng, Tham Pou Kham | Wesener 2019 |
| 104 | Sphaerobelum sp. L07 | MK330979 | ZMUC00040261 | Laos, Khammouane Province, Ban Khounkham [Khun Kham] (Nahin) | Wesener 2019 |
| 105 | Sphaerobelum sp. L10 | MK330980 | SMF | Laos, Vientiane Province, Vang Vieng, W. of Nam Song, Tham Nam Or Khem | Wesener 2019 |
| 106 | S. spinatum Wesener, 2019 | MK330973 | ZMUC00040258 | Laos, Vientiane Province, Phou Khao Khouay | Wesener 2019 |
| 107 | S. truncatum Wongthamwanich, 2012 | JN885184 | FMNH-INS 0000 072 674 | Thailand, Nan Province, Song Khwae District, Na Rai Luang Subdistrict, Pang Hi Village | Wongthamwanich et al. 2012 |
| 108 | S. tujiaphilum Zhao & Liu, 2022 | OP339785 | SCAU BHS01 | China, Guizhou, Tongren City, Jiangkou County, Taiping Town, Baiheshan Village | Zhao et al. 2022 |
| 109 | S. tujiaphilum Zhao & Liu, 2022 | OP339787 | SCAU JXT02 | China, Guizhou, Tongren City, Jiangkou County, Taiping Town, Jiang-xitun Village | Zhao et al. 2022 |
| 110 | S. tujiaphilum Zhao & Liu, 2022 | OP339788 | SCAU SD03 | China, Guizhou, Tongren City, Jiangkou County, Guanhe Town, Sidu Village | Zhao et al. 2022 |
| 111 | S. tujiaphilum Zhao & Liu, 2022 | OP339789 | SCAU DW01 | China, Guizhou, Tongren City, Jiangkou County, Dewang Town, Xiaobang Village | Zhao et al. 2022 |
| 112 | S. turcosa Srisonchai & Pimvichai, 2023 | OR530087 | CUMZ-Zeph0012 | Thailand, Loei Province, Mueang Loei District, Phu Pha Lom Forest Park | Srisonchai et al. 2023 |
| 113 | S. turcosa Srisonchai & Pimvichai, 2023 | OR530087 | CUMZ-Zeph0012 | Thailand, Loei Province, Mueang Loei District, Phu Pha Lom Forest Park | Srisonchai et al. 2023 |
| 114 | Arthrosphaera brandtii (Humbert, 1865) | FJ409915 | FMNH-INS 8650 | Tanzania, Usambara hills | Wesener et al. 2010 |
| 115 | Cryxus ovalis (Linnaeus, 1758) (unverified) | JX486069.2 | ZFMK MYR0824 | Vietnam, Dong Nai Province, Cat Tien National Park | Golovatch et al. 2012 |
| 116 | Epicyliosoma sp. | AF218270 | NA | NA | Edgecombe and Giribet 2004 |
| 117 | Glomeris marginata (Villers, 1789) | FJ409909 | ZFMK Myr009 | Germany, Bonn, Venusberg | Wesener et al. 2010 |
| 118 | P. inthanonense Donworth & Wesener, 2024 | PP297645 | MHNG 4E-2 | Thailand, Chiang Mai Province, Chom Thong District, Doi Inthanon National Park | Donworth and Wesener 2024 |
| 119 | P. inthanonense Donworth & Wesener, 2024 | PP297646 | MHNG 7A | Thailand, Chiang Mai Province, Chom Thong District, Doi Inthanon National Park | Donworth and Wesener 2024 |
| 120 | P. naevium Donworth & Wesener, 2024 | PP297647 | MHNG 4B-1 | Thailand, Yala Province, Than To District, Bang Lang National Park, Than To Waterfall | Donworth and Wesener 2024 |
| 121 | P. naevium Donworth & Wesener, 2024 | PP297648 | NHMD 1184671 | Thailand, Yala Province, Than To District, Bang Lang National Park | Donworth and Wesener 2024 |
| 122 | P. naevium Donworth & Wesener, 2024 | PP297649 | NHMD 1184672 | Thailand, Yala Province, Than To District, Bang Lang National Park | Donworth and Wesener 2024 |
| 123 | P. naevium Donworth & Wesener, 2024 | PP297650 | NHMD 1184673 | Thailand, Yala Province, Than To District, Bang Lang National Park | Donworth and Wesener 2024 |
| 124 | Sphaeromimus splendidus Wesener & Sierwald, 2005 | FJ409917 | FMMC-INS 6702 | Madagascar, Sainte Luce S9 | Wesener et al. 2010 |
The chromatograms of all sequences were examined, aligned, and trimmed using BioEdit v. 7.0.5.3 (https://bioedit.software.informer.com/download/) (Hall 1999) and MEGA X (https://www.megasoftware.net/) (Kumar et al. 2018). Alignments were checked for stop codons, and missing nucleotides were coded as “N”. The best-fit nucleotide substitution model was calculated using JModelTest2 on XSEDE 2.1.6 (Darriba et al. 2012) via the CIPRES Gateway (Miller et al. 2010) which resulted GTR+I+G as the best model.
COI barcoding trees were reconstructed using maximum likelihood (ML) and Bayesian inference (BI) methods. The ML tree was generated using the IQ-tree on XSEDE 1.6.6 (Minh et al. 2020) with the GTR+I+G model and with 10,000 bootstrap replicates. For BI analysis, the dataset was processed in KAKUSAN v. 4.0 (https://kakusan4.software.informer.com/download/#google_vignette) (Tanabe 2011) to select the optimal model, and analyses were run in MrBayes on XSEDE 3.2.7a (Ronquist et al. 2012) via the CIPRES Gateway with a random starting tree and Markov Chain Monte Carlo (MCMC), sampling every 1,000 generations for 50 million generations. Phylogenetic trees were visualised in FigTree v. 1.4.4 (https://tree.bio.ed.ac.uk/software/figtree/) (Rambaut 2018) and finalised in Adobe Illustrator 2025. The BI posterior probabilities (PP) > 95% and ML bootstrap support (BS) > 70% were considered as strong support (Huelsenbeck and Hillis 1993; Larget and Simon 1999).
Interspecific and intraspecific genetic distances were calculated using the uncorrected p-distance model in MEGA X (Kumar et al. 2018), based on pairwise comparisons with pairwise deletion of missing data.
Results
COI sequences annotations and genetic distances
The 658 bp COI gene fragments from 124 sequences contained 376 polymorphic sites, 282 conservative sites, and 316 parsimony informative sites. The genetic distances (percentage) between Zephronia and other closely related genera were from 6.85–25.27% between Sphaerobelum and Zephronia, 16.44–23.29% between Prionobelum and Zephronia, and 18.02–23.38% between Cryxus Leach, 1814 and Zephronia.
Within Zephronia itself, interspecific divergence ranged from 8.68 to 24.20%, with the lowest distance observed between Z. siamensis and Z. dawydoffi. Pairwise interspecific distances between each taxon and its closest congeners within Zephronia were 8.68–21.92% in Z. dawydoffi, 12.79–22.98% in Z. laotica, 10.81–22.07% in Z. tamarindina sp. nov., and 10.81–22.83% in Z. triforma sp. nov. The intraspecific genetic distances reached up to 5.18% in Z. dawydoffi, 5.95% in Z. laotica, 0.61% in Z. tamarindina sp. nov., and 5.63% in Z. triforma sp. nov., respectively. Notably, Z. dawydoffi in this study differed by 3.65–5.18% from the GenBank sequence (MK330971), while Z. laotica differed by 4.88–5.95% from the GenBank sequence (MK330977) (see Suppl. material 1).
Barcoding tree based on COI
COI barcoding tree reconstruction using BI and ML methods produced partially incongruent topologies. However, most interspecific relationships, particularly among Zephronia s.s. from Thailand, Laos, Vietnam, and Cambodia, were broadly consistent (Fig. 1 and see list of species in Zephronia s.s. below).
Figure 1.
COI barcoding trees based on Bayesian Inference (BI) and maximum likelihood (ML) of the genus Zephronia and related genera. Numbers on each node represent posterior probabilities (PP) from BI and bootstrap support (BS) from ML. Background colours indicate the two new species (Zephronia tamarindina sp. nov. and Zephronia triforma sp. nov.), and the two new recorded species from Thailand (Zephronia dawydoffi Attems, 1953 and Zephronia laotica Wesener, 2019), relating to the photograph of live specimens. The scale bar represents the branch length. Colour of scientific letters: blue = outgroup species, black = Zephronia species.
Overall, nodal support across deeper branches was generally low, limiting the resolution of relationships among Zephronia, Sphaerobelum, Prionobelum, and Cryxus. Both BI and ML trees indicated that Zephronia is non-monophyletic. In the BI tree, Zephronia, Sphaerobelum, Prionobelum, and Cryxus were intermixed, forming a poorly resolved polytomy with low support (PP = 0.59). Similarly, in the ML, Zephronia was divided into four major clades with weak support (BS = 47). While most of the Zephronia s.s. clustered together, Z. phrain, Z. viridisoma, and Zephronia sp. (Aow Noi Temple) formed a separate clade. In addition, Z. hui, Z. medogensis, and Z. zhouae were interspersed with Sphaerobelum in two distinct clades.
All other Zephronia s.s. specimens from Thailand, Laos, Vietnam, and Cambodia, including the newly sequenced Z. dawydoffi, Z. laotica, Z. tamarindina sp. nov., and Z. triforma sp. nov., formed a moderately to well-supported monophyletic group in both BI and ML trees (BS = 74, PP = 0.91). Within this clade, the two new species were nested among members of the Zephronia s.s. group (Z. chrysomallos, Z. erawani, Z. golovatchi, Z. lannaensis, and Z. panhai) with strong support (BS = 99, PP = 1.00). Z. tamarindina sp. nov. and Z. triforma sp. nov. were recovered as sister species (BS = 99, PP = 1.00). Z. dawydoffi and Z. laotica were grouped together with Z. chantaburiensis, Z. macula, Z. ovalis, and Z. siamensis with strong support (BS = 79, PP = 1.00). Sequences of Z. dawydoffi and Z. laotica from this study clustered with their respective GenBank references (MK330971 of Z. dawydoffi: BS = 50, PP = 1.00; MK330977 of Z. laotica: BS = 100, PP = 1.00).
Systematics
Class Diplopoda de Blainville in Gervais, 1844
Order Sphaerotheriida Brandt, 1833
Family Zephroniidae Gray, 1843
Subfamily Zephroniinae Gray, 1843
Tribe Zephroniini Gray, 1843
Genus. Zephronia
Gray, 1832
CCC627CB-CB92-5E64-B3EE-5B2471D9F2A4
Type species.
Zephronia ovalis Gray, 1832.
Species included.
59 species, including the two new species described here.
Distribution.
Cambodia, China (including Hong Kong), India (NE), Indonesia, Laos, Malaysia, Myanmar, Nepal, Singapore, Thailand, and Vietnam.
Zephronia is one of the most species-rich genera within Zephroniidae, currently comprising 59 described species. Many species remain insufficiently studied, especially type re-examinations are lacking, with many known only from females, particularly those from Myanmar, Borneo, Sumatra, and India. Consequently, the genus is in urgent need of a revision, and some species currently placed in Zephronia may be transferred to separate genera in the future.
Zephronia differs from other genera of Zephroniinae by the following combination of characters: endotergum weakly modified; posterior margin usually flat (rarely modified); outer area without setae; marginal bristles arranged in 1–5 rows; middle area often with a single row of circular cuticular impressions; tarsi of leg pairs 5–21 usually with more than one apical spine (rarely with a single apical spine) and several ventral spines; male anterior telopods with four podomeres distal to syncoxite; telopoditomere 2 bearing a large, curved process forming a clamp-like structure; telopoditomeres 3 and 4 simple; male posterior telopods with four telopoditomeres; process of telopoditomere 2 slender and apically curved; telopoditomeres 3 and 4 with a membranous ledge; telopoditomere 3 with a row of large, crenulated, sclerotised teeth; telopoditomere 4 with one or two sclerotised spines; female vulvae conspicuous and slender, operculum usually rounded.
See more recent diagnoses for Zephronia sensu lato and Zephronia sensu stricto in Srisonchai et al. (2024).
Zephronia sensu stricto
Zephronia s.s. currently includes Z. chantaburiensis, Z. chrysomallos, Z. dawydoffi, Z. enghoffi, Z. erawani, Z. golovatchi, Z. hui Liu & Wesener, 2022, Z. konkakinhensis Semenyuk, Golovatch & Wesener, 2018, Z. lannaensis, Z. laotica, Z. macula, Z. medogensis Zhao & Liu, 2022, Z. montis Semenyuk, Golovatch & Wesener, 2018, Z. ovalis, Z. panhai, Z. phrain, Z. siamensis, Z. sukhothaiensis, Z. tamarindina sp. nov., Z. tratensis, Z. triforma sp. nov., Z. zhouae Zhao & Liu, 2022.
List of 18 Zephronia species in Thailand
Z. chantaburiensis Srisonchai & Wesener, 2024
Z. chrysomallos Bhansali & Wesener, 2022
Z. dawydoffi Attems, 1953
Z. enghoffi Srisonchai & Likhitrakarn, 2021
Z. erawani Bhansali & Wesener, 2022
Z. golovatchi Srisonchai & Likhitrakarn, 2021
Z. lannaensis Likhitrakarn & Golovatch, 2021
Z. laotica Wesener, 2019
Z. macula Srisonchai & Wesener, 2024
Z. ovalis Gray, 1832
Z. panhai Srisonchai & Likhitrakarn, 2021
Z. phrain Likhitrakarn & Golovatch, 2021
Z. siamensis Hirst, 1907
Z. sukhothaiensis Srimongkol & Srisonchai, 2026
Z. tamarindina sp. nov.
Z. tratensis Srimongkol & Srisonchai, 2026
Z. triforma sp. nov.
Z. viridisoma Rosenmejer & Wesener, 2021
Among the examined material, colour variation initially suggested the presence of multiple distinct taxa. In particular, one species, Z. triforma sp. nov., exhibits three distinct colour morphs, which could be misinterpreted as representing separate species based on external appearance alone. In contrast, Z. tamarindina sp. nov. and the two previously described species each show a single, consistent colour form. However, integrative analyses combining morphological characters and COI sequence data confirm that the three colour morphs belong to a single species, Z. triforma sp. nov., whereas the remaining populations correspond to two new species and two previously described species.
In this study, we focus on describing the two new species and the two newly recorded species from Thailand.
Zephronia dawydoffi
Attems, 1953
58B0FAD1-D1BE-5E98-A465-E747FFC89F83
Figs 1, 2, 3, 4, 5, 6, 22A, B, 23A–E, 24
Figure 2.
Photograph of live specimens of Zephronia dawydoffi Attems, 1953 and habitats. A–G. Live specimens of a population from Khon Kaen Province, Thailand; H. Pile of leaf litter; I. Agricultural area. Scale bars: 5.0 mm.
Figure 3.
Zephronia dawydoffi Attems, 1953, ♂ from Thung Setthi Temple, Khon Kaen Province, Thailand (MZKKU) — SEM. A. Collum, dorsal view; B. Head, anterior view; C. Antenna, lateral view; D. Tömösváry’s organ; E, F. Apical cones, lateral view; G, J. Gnathochilarium, anterior and ventral views, respectively; H. Sensory cones on inner palpi, ventral view; I. Sensory cones on central pad, ventral view; K. Epipharynx, ventral view; L. Right mandible, mesal view. Abbreviations: 3it = 3-combed inner tooth, co = condylus, Cp = central pad, ct = central tooth, et = external tooth of epipharynx, Et = external tooth of mandible, Ia = inner area, il = incisura lateralis, ip = inner palpi, ll = lamellae linguales, me = mentum, mp = molar plate, o = ommatidia, pl = pectinate lamellae, rsp = row of spines, sc = sensory cone, st = stipites, t = Tömösváry’s organ. Scale bars in millimetres.
Figure 4.
Zephronia dawydoffi Attems, 1953, ♂ and ♀ from Thung Setthi Temple, Khon Kaen Province, Thailand (MZKKU) — SEM. A–C. Surface of midbody tergite, all in dorsal views (overview, anterior margin, surface, respectively); D. Subanal plate; E. Anal shield, underside, ventral view; F. Locking carinae; G. Surface of anal shield; H. First pleurite; I. Midbody pleurite. Scale bars in millimetres.
Figure 5.
Zephronia dawydoffi Attems, 1953, ♂ and ♀ from Thung Setthi Temple, Khon Kaen Province, Thailand (MZKKU) — SEM. A. Legs 1; B. Legs 2 with gonopores; C. Leg 2 with vulvae; D. Midbody legs (arrow points to femoral ridge); E. Small triangular spines on femur; F. Coxal process on midbody legs. Abbreviation: bu = bursa, cx = coxa, fe = femur, op = operculum, po = postfemur, pre = prefemur, rdg = femoral ridge, st-pl = stigmatic plate, ta = tarsus, ti = tibia. Scale bars in millimetres.
Figure 6.
Zephronia dawydoffi Attems, 1953, ♂from Thung Setthi Temple, Khon Kaen Province, Thailand (MZKKU) — SEM. A–C. Overview of telopods (anterior, posterior, and ventral views, respectively); D. Crenulated teeth of posterior telopods, posterior view; E. Sclerotised spots on immovable finger of posterior telopod, sublateral view; F. Anterior telopod, ventral view; G. Inner horns, anterior view. Abbreviations: cr-t = crenulated teeth, ml = membranous lobe, scl-s = sclerotised spots, syn-cx = syncoxite. Scale bars in millimetres.
Figure 22.
Endoterga of thoracic shields and midbody tergites — SEM. A, B. Zephronia dawydoffi Attems, 1953 (♂, MZKKU); C, D. Zephronia laotica Wesener, 2019 (♂, MZKKU); E, F. Zephronia tamarindina sp. nov. (♂ paratype, MZKKU); G, H. Zephronia triforma sp. nov. (♂ paratype, MZKKU). Abbreviations: cp = cuticular impression, ia = inner area, ma = middle area, oa = outer area, pm = posterior margin. Scale bars in millimetres.
Figure 23.
Drawing of telopods of some Zephronia species. A–E. Zephronia dawydoffi Attems, 1953; F–J. Zephronia laotica Wesener, 2019; K–O. Zephronia tamarindina sp. nov.; P–T. Zephronia triforma sp. nov.; A, F, K, P. Sublateral view of left anterior telopods; B, G, L, Q. Anterior view of left anterior telopods; C, H, M, R. Posterior view of left anterior telopods; D, I, N, S. Anterior view of left posterior telopods; E, J, O, T. Posterior view of left posterior telopods. Abbreviations: cr-t = crenulated teeth, ml = membranous lobe, scl-s = sclerotised spots, syn-cx = syncoxite, sp = spine. Scale bars: 0.5 mm.
Figure 24.
Distribution map of Zephronia species in Thailand. Number inside the circle indicates species: 1 = Z. chantaburiensis Srisonchai & Wesener, 2024; 2 = Z. chrysomallos Bhansali & Wesener, 2022; 3 = Z. dawydoffi Attems, 1953; 4 = Z. enghoffi Srisonchai & Likhitrakarn, 2021; 5 = Z. erawani Bhansali & Wesener, 2022; 6 = Z. golovatchi Srisonchai & Likhitrakarn, 2021; 7 = Z. lannaensis Likhitrakarn & Golovatch, 2021; 8 = Z. laotica Wesener, 2019; 9 = Z. macula Srisonchai & Wesener, 2024; 10 = Z. ovalis Gray, 1832; 11 = Z. panhai Srisonchai & Likhitrakarn, 2021; 12 = Z. phrain Likhitrakarn & Golovatch, 2021; 13 = Z. siamensis Hirst, 1907; 14 = Z. sukhothaiensis Srimongkol & Srisonchai, 2026; 15 = Z. tamarindina sp. nov.; 16 = Z. tratensis Srimongkol & Srisonchai, 2026; 17 = Z. triforma sp. nov.; 18 = Z. viridisoma Rosenmejer & Wesener, 2021. Colours (yellow, green, purple, red) indicate specimens examined in this study.
Zephronia dawydoffi Attems, 1953: 156.
Zephronia dawydoffi — Jeekel 2001: 18; Likhitrakarn et al. 2015: 177; Wesener 2016: 31; Wesener 2019: 205; Likhitrakarn et al. 2021: 23; Rosenmejer et al. 2021: 111; Srisonchai et al. 2021: 26; Bhansali and Wesener 2022: 359; Donworth and Wesener 2024: 547; Srisonchai et al. 2024: 30; Srimongkol et al. 2026: 31.
Material examined.
• 18 ♂♂ 33 ♀♀ (MZKKU); Thailand, Khon Kaen Province, Mueang District, Thung Setthi Temple; 16°24'33"N, 102°53'05.7"E; ca. 150 m a.s.l.; 12 July 2022; leg. C. Wilaisorn and MZKKU students; • 5 ♂♂ 7 ♀♀ (MZKKU); Thailand, Buri Ram Province, Khu Mueang District, Dong Kheng rubber plantation; 15°19'46"N, 103°00'59"E; ca. 159 m a.s.l.; 6 July 2022; leg. C. Wilaisorn and MZKKU students; • 4 ♂♂ 2 ♀♀ (MZKKU); Thailand, Buri Ram Province, Mueang District, Khao Kradong; 14°56'21.5"N, 103°05'28.8"E; ca. 213 m a.s.l.; 10 September 2023; leg. C. Wilaisorn and MZKKU students; • 3 ♀♀ (MZKKU); Thailand, Buri Ram Province, Mueang District, Ban Khok Ta Sing Waterfall; 14°55'22.8"N, 103°06'57.9"E; ca. 180 m a.s.l.; 5 June 2022; leg. C. Wilaisorn and MZKKU students. • 12 ♂♂ 21 ♀♀ (MZKKU); Thailand, Buri Ram Province, Khu Mueang District, Non Somboon Monastery; 15°16'32"N, 102°59'13"E; ca. 200 m a.s.l.; 31 July 2022; leg. C. Wilaisorn and MZKKU students.
Re-diagnosis based on Thai specimens.
In Z. dawydoffi, the Tömösváry’s organ is positioned at the brim rather than inside the antennal groove (Fig. 3B, C), confirming its placement within Zephronia s.s. species group (see Semenyuk et al. 2018), which is also supported by genetic evidence (Fig. 1). Z. dawydoffi differs from all other Zephronia s.s. species, except for Z. laotica, Z. ovalis, and Z. siamensis, in the presence of colour patches on the tergites as well as in the posterior margin of the endotergum which is modified (Fig. 22A, B), and the lack of an apical spine in the third leg-pair. It differs from Z. laotica, Z. ovalis, and Z. siamensis in the shape of the anterior telopods with the process of telopoditomere 2 broadened, shorter than telopoditomere 3+4 (Figs 6C, 6F, 23A–C), the process of telopoditomere 2 of the posterior telopods long (Figs 6B, 23D, 23E), and the presence of two locking carinae on the underside of anal shield (Fig. 4F; except for Z. laotica). The genetic differentiation of the 658 bp COI fragment between Z. dawydoffi and other Zephronia ranged from 8.68 to 21.92%.
Type locality.
CAMBODIA (Ream, Sre Umbell; Kampot, Kampong Speu).
Description of specimens from Thailand.
Measurements. Males: body length = 10.5–18.8 mm; width (broadest), of thoracic shield = 5.3–8.6 mm, of tergite 7 = 5.6–9.3 mm; highest of thoracic shield = 3.1–5.5 mm, of tergite 7 = 3.3–6.9 mm. Females: body length = 11.5–22.0 mm; width (broadest), of thoracic shield = 5.8–10.6 mm, of tergite 7 = 6.4–11.7 mm; highest of thoracic shield = 4.0–7.1 mm, of tergite 7 = 4.4–8.2 mm.
Colouration (Fig. 2A–G). Live specimens dark green with yellow semicircular colour markings. Head and collum dark green. Thoracic shield and tergites dark green (rarely greenish-brown or dark brown), each with yellowish brown posterior bands and two yellow (rarely pale yellow) dorsal patches per tergite. Anal shield dark green with a conspicuous yellow patch anteriorly, and orangish brown on posterior margin. Antenna and legs green. Venter pale brown. Preserved specimens in 95% ethanol after 1.5 years changed to brownish green, some faded to yellowish green.
Head (Fig. 3B–D). Trapeziform, broad, stout; densely setose over entire surface including mouthparts. With 77–93 ommatidia (ocelli). Aberrant ommatidium situated at brim of antennal groove. Tömösváry’s organ separated from eye field and located between base of antenna and ommatidia. No sclerotised ridge between antennal groove and ommatidia.
Antennae (Fig. 3B, C, E, F). Short and stout; emerging from sides of head, covered by noticeable long setae; last antennomere reaches back posteriorly to leg pair 2. Lengths of antennomeres in descending order: 6 > 5 > 4 = 3 > 2 > 1. Antennomere 6 flattened, axe-shaped; with sensilla basiconica around apical disc. Apical disc flat; with 59–73 apical cones in males, and 44–62 apical cones in females.
Epipharynx (Fig. 3K). Apically with a triangular projected central tooth (ct); with conspicuous inner tooth; inner area with a row of triangular fringed spines (rsp); outer area with several slender external teeth (et).
Gnathochilarium (Fig. 3G–J). Lamellae linguales (ll) rectangular, apically concave; covered by long setae. Central pads (Cp) modified; with two types of sensory cones (sc), first type small without tubercle apically, second type larger with a concave pad apically containing a single internal tubercle. Stipites (st) robust, with dense and long setae, located laterally to lamellae linguales. Mentum (me) broad and fused, densely setose. Lateral palpi inconspicuous. Inner palpi (ip) with numerous cylindrical sensory cones (sc) located in single field, each cone concave apically and containing a single internal tubercle.
Mandibles (gnathal lobe) (Fig. 3L). With single undivided external tooth (Et) and 3-combed inner tooth (3it). With 4–5 rows of pectinate lamellae (pl). Inner area (Ia) with several rows of small slender teeth. Molar plate (mp) relatively flat. Condylus (co) conspicuous, apically with a single ridge.
Tegument (Figs 2A–G, 4). Glabrous; collum, thoracic shield, tergites and anal shield covered by tiny setae; each seta emerged from a pit. Tergites and anal shield sparsely setose anteriorly and without setae posteriorly.
Collum (Fig. 3A). Subsemicircular; lateral edges triangular, blunt; with a few long setae.
Thoracic shield. Anterior margin with shallow canal covered with a few scattered long setae, with 5–7 small keels.
Midbody tergite (Fig. 4A–C). Dorso-anterior margin with a row of circular impressions and small tubercles. Inner area with a shallow groove, separated from anterior margin by a row of crenate barriers. Tips of paratergites projected posteroventrally.
Anal shield (Fig. 4E–G). Sexually dimorphic, females well-rounded, males rectangular and slender. Anteriorly with a row of circular impressions and small tubercles. Inner area with a shallow groove, separated from margin by a row of crenate barriers. Underside with two dark locking carinae; length of each locking carina as long as those of tergites; densely setose especially on lateral margin.
Endotergum of thoracic shield and midbody tergite (Fig. 22A, B). Thoracic shield similar to midbody tergite. Posterior margin (pm) distinctly modified, with rectangular projections, length of each projection being longer than height. Outer area (oa) with several small denticles. Marginal bristles arranged in two rows; tips of the longest bristles not reaching to posterior margin. Middle area (ma) with a single row of oval cuticular impressions (cp); distance between each impression almost twice as long as individual diameter. Cuticular impressions of thoracic shield shallower than those of midbody tergite. Inner area (ia) with long setae.
Pleurite (laterotergite) (Fig. 4H, I). Densely setose. First pleurite boomeranglike, with pointed edge, reaching towards paratergite. Pleurite 2 slightly widened. The remaining pleurites flat, rectangular.
Subanal plate of female (Fig. 4D). Densely setose; wide; triangular; apical margin weakly concave, narrow.
Stigmatic plates (Fig. 5A). First stigmatic plate quite slender, flat antero-posteriorly; semicircular; apex round. Second stigmatic plate in both sexes triangular.
Legs (Fig. 5). All podomeres densely setose. Coxa (cx) large, as long as length of prefemur (pre); first and second leg-pairs without coxal process; leg-pairs 3–21 with large and serrated processes. Prefemur wide, stout; apico-mesally without projection. Femur (fe) slightly long, 1.5 × longer than prefemur; with conspicuous long ridge (rdg); apico-mesally with inconspicuous projection; mesal margin dentate, with seven or eight small triangular microscopic spines (sp). Postfemur (po) and tibia (ti) short. Tarsus (ta) of midbody legs long and slender, shorter than femur+postfemur; first three leg-pairs without an apical spine; leg-pair 1 with 1–3 ventral spines; leg-pair 2 with two or three ventral spines; leg-pair 3 with 3–5 ventral spines; leg pair 4–21 with 6–9 ventral spines and two or three apical spines. In leg 10, femur 1.5 ×, tarsus 3 × longer than wide. Claw normal, with small notch at base.
Male sexual characters (Fig. 5B). Gonopore surrounded by long setae; covered with a divided, sclerotised plate. Apical part of coxa 2 without membranous process.
Anterior telopods (Figs 6A, 6C, 6F, 23A–C). Consisting of four telopoditomeres. First telopoditomere conspicuous, rectangular, slightly longer than wide. Telopoditomere 2 large. Process of telopoditomere 2 (= immovable finger) broad; shorter than combination of telopoditomeres 3 and 4 (= movable finger); clearly seen in posterior view; strongly curved toward midway of movable finger; inner margin with a single membranous lobe and numerous sclerotised spots (scl-s). Telopoditomere 3 long and slender; twice as long as telopoditomere 4; partly demarcated from telopoditomere 4 by shallow suture (rarely fused with telopoditomere 4); inner margin with single spine; apically with five or six small crenulated teeth (cr-t) and two conspicuous spines. Telopoditomere 4 tip obtuse. All telopoditomeres densely setose, except for basal part of telopoditomere 1 and apical part of immovable finger.
Posterior telopods (Figs 6A–E, 6G, 23D, 23E). Consisting of four telopoditomeres. First telopoditomere swollen, broad; as wide as long. Telopoditomere 2 large and slender. Process of telopoditomere 2 (= immovable finger) quite long, 2.5 × longer than wide; shorter than a combination of telopoditomeres 3 and 4 (= movable finger); apically obtuse, slightly curved; inner margin with two membranous lobes (ml) and numerous conspicuous sclerotised spots (scl-s). Telopoditomere 3 long and slender; 2.5 × longer than wide; with a large membranous ledge and single spine at inner margin; posteriorly with a row of nine or ten crenulated teeth (cr-t). Telopoditomere 4 short; 2.5 × shorter than telopoditomere 3; 1.5 × longer than wide; tip tapering; inner margin with two long spines located on a large membranous ledge. Telopoditomeres 1 and 2 covered by long setae anteriorly, sparse setae posteriorly. Telopoditomere 3 sparsely setose at inner margin. Telopoditomere 4 glabrous. Inner horns densely setose, swollen at base; tips pointed, directed posteriad.
Female sexual characters (Fig. 5C). Vulva conspicuous, large, with a few long setae; covering more than half of coxa; located at mesal margin; extending mesally to base of prefemur. Operculum (op) round and slender, rectangular; tip round. Bursa (bu) large, fused into triangular shape, clearly separated from operculum by triangular groove. Apical part of coxa 2 without coxal process.
Remarks.
Variation in body colouration and pattern was observed among specimens. Most individuals displayed dark green tergites, while others exhibited greenish-brown or dark brown tones. Typically, two yellow patches were present on dorsal tergites, though in some specimens these patches appeared faded or paler in colour. The patch shapes also varied, most commonly forming two semicircular markings (Fig. 2A, C, F). In addition, telopoditomeres 3 and 4 of anterior telopods are only partly demarcated in most individuals (Fig. 23A–C), but in some specimens appear completely fused (Fig. 6A, C).
Morphological differences were observed between Thai specimens and the original description by Attems (1953), as well as in comparison with the syntypes deposited in the NHMW. The body size of the type specimens was between 11.0–13.0 mm in length and 5.8–6.0 mm in width, whereas the Thai specimens were larger, with a range of 10.5–22.0 mm in length and 5.6–11.7 mm in width. The thoracic shield of the Thai individuals bears 5–7 weak keels, which are absent from the type description. Furthermore, the posterior margin of the endotergum is described as flat in the type material, but appears modified in the Thai specimens. In the original description, telopoditomeres 3 and 4 of the anterior telopods are fused together, while those of Thai specimens were usually separated by a shallow suture, with only a very few specimens showing a complete fusion. Similarly, telopoditomere 2 of posterior telopods was described as having a single membranous lobe, while the Thai material consistently exhibits two lobes (like most species in the genus). These differences are interpreted as intraspecific variation within the species. In addition, some apparent discrepancies between the type specimens and the Thai material likely result from differences in observational resolution and the use of modern imaging techniques, which allow finer morphological details to be detected.
Distribution and habitat.
Zephronia dawydoffi in Thailand is currently known from two provinces in the northeastern region: four localities in the Buri Ram Province and only one locality in the Khon Kaen Province (Fig. 24). This species inhabits agricultural areas, particularly rubber plantations characterised by tall trees, limited sunlight, and fine soil. Specimens were primarily collected during the day, typically found sheltering beneath leaf litter piles (Fig. 2H, I).
Compared with its type locality in southern Cambodia, the known distribution of Z. dawydoffi is extended into Thailand, representing a geographic range spanning approximately 300–700 km.
Zephronia laotica
Wesener, 2019
636ABD8D-CAAE-5F83-B5F9-C4954AEE00E6
Figs 1, 7–11, 22C, D, 23F–J, 24
Figure 7.
Photograph of live specimens of Zephronia laotica Wesener, 2019 and habitats. A–I. Live specimens of a population from Si Sa Ket Province, Thailand; J, K. Agricultural areas. Scale bars: 5.0 mm.
Figure 11.
Zephronia laotica Wesener, 2019, ♂ from Mae Lamoon Durian plantation, Si Sa Ket Province, Thailand (MZKKU) — SEM. A–C. Overview of telopods (anterior, posterior, and ventral views, respectively); D. Crenulated teeth of posterior telopods, posterior view; E. Sclerotised spots on immovable finger of posterior telopod, sublateral view; F. Anterior telopod, ventral view; G. Inner horns, anterior view. Abbreviations: cr-t = crenulated teeth, ml = membranous lobe, scl-s = sclerotised spots. Scale bars in millimetres.
Zephronia laotica Wesener, 2019: 205.
Zephronia laotica — Srisonchai et al. 2021: 24; Likhitrakarn et al. 2021: 23; Rosenmejer et al. 2021: 111; Bhansali and Wesener 2022: 359; Srisonchai et al. 2023: 44; Donworth and Wesener 2024: 547; Srisonchai et al. 2024: 30; Sapparojpattana et al. 2025: 53; Sapparojpattana et al. 2026: 56; Srimongkol et al. 2026: 31.
Material examined.
• 10 ♂♂ 7 ♀♀ (MZKKU); Thailand, Si Sa Ket Province, Khun Han District, Mae Lamoon Durian plantation; 14°33'00"N, 104°31'51"E; ca. 228 m a.s.l.; 29 July 2022; leg. C. Wilaisorn and MZKKU students; • 10 ♂♂ 12 ♀♀ (MZKKU); Thailand, Si Sa Ket Province, Khun Han District, Kantrom Tai Temple; 14°34'32"N, 104°20'33"E; ca. 188 m a.s.l.; 6 October 2024; leg. C. Wilaisorn and MZKKU students; • 2 ♀♀ (MZKKU); Thailand, Si Sa Ket Province, Khun Han District, Ta Nuan Rubber plantation; 14°33'47.9"N, 104°21'24.2"E; ca. 180 m a.s.l.; 10 June 2023; leg. C. Wilaisorn and MZKKU students.
Re-diagnosis based on Thai material.
The position of the Tömösváry’s organ is located at the brim rather than inside the antennal groove (Fig. 8B, C), confirming the placement of Z. laotica as a member of Zephronia s.s. species group. The presence of colour patches on tergites, as well as a modified posterior margin of the endotergum, and the lack of an apical spine in the third leg-pair are three characters only shared with Z. dawydoffi, Z. ovalis, and Z. siamensis. Z. laotica differs from them in the combination of the following characters: process of telopoditomere 2 of anterior telopods wide (Figs 11F, 23F, 23H); process of telopoditomere 2 of posterior telopods long and swollen (Figs 11B, 23I, 23J); two locking carinae on the underside of the anal shield (Fig. 9F) (except for Z. dawydoffi). The genetic differentiation between Z. laotica and other Zephronia species ranged from 12.79 to 22.98% of COI sequences.
Figure 8.
Zephronia laotica Wesener, 2019, ♂ from Mae Lamoon Durian plantation, Si Sa Ket Province, Thailand (MZKKU) — SEM. A. Collum, dorsal view; B. Head, anterior view; C. Antenna, lateral view; D. Tömösváry’s organ; E, F. Apical cones, lateral view; G, J. Gnathochilarium, anterior and ventral views, respectively; H. Sensory cones on inner palpi, ventral view; I. Sensory cones on central pad, ventral view; K. Epipharynx, ventral view; L. Right mandible, mesal view. Abbreviations: 3it = 3-combed inner tooth, co = condylus, Cp = central pad, ct = central tooth, et = external tooth of epipharynx, Et = external tooth of mandible, Ia = inner area, il = incisura lateralis, ip = inner palpi, ll = lamellae linguales, me = mentum, mp = molar plate, o = ommatidia, pl = pectinate lamellae, rsp = row of spines, sc = sensory cone, st = stipites, t = Tömösváry’s organ. Scale bars in millimetres.
Figure 9.
Zephronia laotica Wesener, 2019, ♂ and ♀ from Mae Lamoon Durian plantation, Si Sa Ket Province, Thailand (MZKKU) — SEM. A–C. Surface of midbody tergite, all in dorsal views (overview, anterior margin, surface, respectively); D. Subanal plate; E. Anal shield, underside, ventral view; F. Locking carinae (arrowheads point to carinae); G. Surface of anal shield; H. First pleurite; I. Midbody pleurite. Scale bars in millimetres.
Type locality.
LAOS, Champasak Province, east of Mekong, Garden of Erawan Riverside Hotel.
Description of specimens from Thailand.
Measurements. Males: body length = 10.2–15.2 mm; width (broadest), of thoracic shield = 5.2–7.9 mm, of tergite 7 = 5.5–8.1 mm; highest of thoracic shield = 4.4–6.6 mm, of tergite 7 = 3.8–6.1 mm. Females: body length = 11.4–15.5 mm; width (broadest), of thoracic shield = 5.8–10.6 mm, of tergite 7 = 6.2–11.1 mm; highest of thoracic shield = 4.0–7.8 mm, of tergite 7 = 4.3–8.1 mm.
Colouration (Fig. 7A–I). Specimens in life greenish brown or yellowish brown. Thoracic shield and tergites greenish brown, with pale brown posterior bands. Some individuals with two triangular yellow dorsal patches per tergite. Anal shield brown, posterior margin pale brown. Antenna and legs green. Venter pale brown. Specimens in 95% ethanol changed to dark brown after two years of preservation.
Head (Fig. 8B–D). Trapeziform, broad, short; sparsely setose; anterior part and especially mouthparts densely setose. With 66–89 ommatidia (ocelli). Aberrant ommatidium situated at brim of antennal groove. Tömösváry’s organ separated from eye field and located between base of antenna and ommatidia. No sclerotised ridge between antennal groove and ommatidia.
Antennae (Fig. 8B, C, E, F). Short and stout; emerging from sides of head, covered by dense setae; last antennomere reaching back posteriorly to leg pair 3. Lengths of antennomeres in descending order: 6 > 5 > 4 > 3 = 2 = 1. Antennomere 6 flattened, axe-shaped; with a few sensilla basiconica around apical disc. Apical disc flat; with 45–83 apical cones in males, and 41–50 apical cones in females.
Epipharynx (Fig. 8K). Apically with a single triangular central tooth (ct); in the middle with a conspicuous, long, and slender inner tooth; inner area with a single row of triangular fringed spines (rsp); outer area with several pointed and long external teeth (et).
Gnathochilarium (Fig. 8G–J). Lamellae linguales (ll) rectangular, slightly concave; covered by long setae. Central pads (Cp) modified, with two types of sensory cones (sc), first small without tubercle apically, second one larger with a concave pad apically containing a single internal tubercle. Stipites (st) large and thick, with dense and long setae; located laterally to lamellae linguales. Mentum (me) broad and fused, with dense and long setae. Lateral palpi inconspicuous. Inner palpi (ip) with numerous sensory cones (sc) located in a single field, each cone concave apically and containing a single internal tubercle.
Mandibles (gnathal lobe) (Fig. 8L). With single undivided external tooth (Et) and 3-combed inner tooth (3it). With 4–5 rows of pectinate lamellae (pl). Inner area (Ia) with several rows of small, slender teeth. Molar plate (mp) relatively flat. Condylus (co) conspicuous; apically with a single ridge.
Tegument (Figs 7A–I, 9). Quite dull; collum, thoracic shield, tergites and anal shield covered by golden setae; each seta emerged from a pit. Anterior margins of tergites and anal shield with fewer setae than posterior one. Posterior rim with bare setae dorsally and ventrally.
Collum (Fig. 8A). Subsemicircular; lateral edges triangular, with sparse setae.
Thoracic shield. Anterior margin with shallow canal covered by numerous long setae; with 5–8 conspicuous keels.
Midbody tergite (Fig. 9A–C). Dorso-anterior margin with a row of circular impressions and numerous small tubercles. Inner area with a shallow groove, separated from anterior margin by a row of crenate barriers. Tips of paratergites projected posteroventrad.
Anal shield (Fig. 9E–G). Slightly sexually dimorphic, females well-rounded, males rectangular and slender. Sparsely setose. Anteriorly with a row of circular impressions and numerous small tubercles. Inner area with a shallow groove, separated from margin by a row of crenate barriers. Underside with two dark locking carinae; twice as long as those of tergites when combined.
Endotergum of thoracic shield and midbody tergite (Fig. 22C, D). Thoracic shield slightly different from midbody tergite. Posterior margin (pm) regularly flat in thoracic shield while midbody tergite modified with rectangular projection, length of each projection being longer than height. Both thoracic shield and midbody tergite; outer area (oa) with several small denticles; marginal bristles arranged in 1–2 rows, tips of the longest bristles almost not extending over posterior margin; middle area (ma) with a row of oval cuticular impressions (cp), distance between each impression almost the same as individual diameter; inner area (ia) with a few long setae.
Pleurite (laterotergite) (Fig. 9H, I). Densely setose. First pleurite boomeranglike, tip attenuated and pointed. Pleurite 2 wide, tip more rounded. Pleurites 3–12 broad and wide; flat; rectangular; tip reduced in size, forming a small process.
Subanal plate of female (Fig. 9D). Densely setose; wide; triangular; apical margin round and narrow.
Stigmatic plates (Fig. 10A). First stigmatic plate slender; slightly attenuate; apex round, slightly curved towards coxa. Second stigmatic plate in both sexes swollen; shorter than first one; tip without curve.
Figure 10.
Zephronia laotica Wesener, 2019, ♂ and ♀ from Mae Lamoon Durian plantation, Si Sa Ket Province, Thailand (MZKKU) — SEM. A. Legs 1; B. Legs 2 with gonopores; C. Leg 2 with vulvae; D. Midbody legs (arrow points to femoral ridge); E. Small triangular spines on femur; F. Coxal process on midbody legs. Abbreviation: bu = bursa, cx = coxa, fe = femur, op = operculum, po = postfemur, pre = prefemur, rdg = femoral ridge, st-pl = stigmatic plate, ta = tarsus, ti = tibia. Scale bars in millimetres.
Legs (Fig. 10). All podomeres densely setose. Coxa (cx) large; first and second leg-pairs without coxal process; leg-pairs 3–21 with serrated processes. Prefemur (pre) rectangular; with short ridge (rdg); apico-mesally with a very weak projection; mesal margin without triangular spines. Femur (fe) long; 1.5 × longer than prefemur; with conspicuous ridge (rdg); apico-mesally with a strong projection; mesal margin dentate, with 12–16 small triangular microscopic spines. Postfemur (po) and tibia (ti) short. Tarsus (ta) of midbody legs long and slender, as long as length of femur+postfemur; first three leg-pairs without an apical spine; leg-pair 1 with one or two ventral spines; leg-pair 2 with two or three ventral spines; leg-pair 3 with 3–5 ventral spines; leg pair 4 and 5 with five or six ventral spines and one or two apical spines; leg pairs 6–18 with 6–8 ventral spines and two apical spines; leg pair 19–21 with 5–7 ventral spines and one or two apical spines. In leg 10, femur 1.5 × and tarsus 2.5 × longer than wide. Claw normal; with small notch at base.
Male sexual characters (Fig. 10B). Gonopore triangular; covered with an undivided, triangular, sclerotised plate. Apical part of coxa 2 without membranous process.
Anterior telopods (Figs 11A, 11C, 11F, 11G, 23F–H). Consisting of four telopoditomeres. First telopoditomere rectangular; slightly longer than wide. Telopoditomere 2 large. Process of telopoditomere 2 (= immovable finger) wide; shorter than movable finger (= combination of telopoditomeres 3 and 4); clearly seen in posterior view; strongly curved toward movable finger; inner margin with a single membranous lobe and numerous sclerotised spots (scl-s). Telopoditomere 3 slender; almost twice as long as telopoditomere 4; clearly demarcated from telopoditomere 4 by shallow suture; inner margin with tiny single spine; apically with four or five crenulated teeth (cr-t). Telopoditomere 4 short; tip round, with two conspicuous spines. All telopoditomeres covered by long sparse setae, except for basal part of telopoditomere 1 and tip of telopoditomere 2.
Posterior telopods (Figs 11A–E, 11G, 23I, 23J). Consisting of four telopoditomeres. First telopoditomere rectangular; stout; slightly wider than long. Telopoditomere 2 large and wide. Process of telopoditomere 2 (= immovable finger) long and swollen, twice as long as wide; slightly longer than a combination of telopoditomeres 3 and 4 (= movable finger); rounded apically; slightly curved; inner margin with two membranous lobes (ml) and numerous conspicuous sclerotised spots (scl-s). Telopoditomere 3 long and slender; twice as long as wide; inner margin with a large membranous ledge and single long spine; posteriorly with a row of 11–13 crenulated teeth (cr-t). Telopoditomere 4 quite short; 3.5 × shorter than telopoditomere 3; twice as long as wide tip; inner margin with two long spines located on membranous ledge. Telopoditomeres 1 and 2 sparsely setose on anterior surface, glabrous on posterior surface. Telopoditomere 3 sparsely setose. Telopoditomere 4 glabrous. Inner horns densely setose; slightly attenuate near tip.
Female sexual characters (Fig. 10C). Vulva large, sparsely setose; covering almost 1/3 of coxa; located mesoventrally; mesally reaching to base of prefemur. Operculum (op) large; well-rounded; with rounded tip. Bursa (bu) wide; fused; separated from operculum by shallow triangular groove. Apical part of coxa 2 without coxal process.
Remarks.
Noticeable variations occur in colouration and patterns of tergites. Most specimens display two yellow patches on dorsal tergites, typically semicircular or rectangular in shape (Fig. 7A, E). However, in some individuals, these patches may fade to a paler hue or completely absent (Fig. 7A, H).
The Thai specimens differ from the original description by Wesener (2019) in some morphological features. They have a greater range of body sizes, with males usually being smaller and females slightly larger, and they vary more in width and height. The tergites feature triangular yellow patches instead of the bright green of the type material. The aberrant ocellus of the Thai specimens is situated close to the brim of the antennal groove rather than inside. The number of apical sensory cones varies more widely and is greater in female Thai specimens (males 45–83; females 41–50). In the original description, the posterior margin of the endotergum was flat, but in Thai specimens, it was modified. The tegument of Thai specimens is dull and densely covered in golden setae, in contrast to the type specimens, which have a smooth, shiny, and glabrous surface (T. Wesener, pers. comm., re-examination of the type material).
In contrast to the type specimens, the paratergites are more noticeably protruding posteroventrad, and the thoracic shield comprises 5–8 keels. The legs of the Thai specimens differ slightly from what was originally described. Thai specimens possessed 12–16 small triangular spines on their femurs, while no spines were mentioned in the original description. Because these spines are minute and the original description was based on light microscopy only, their absence from Wesener (2019) most probably reflects the limits of that method rather than a genuine difference between the populations. The tarsus has somewhat reduced number of ventral and apical spines and is correspondingly shorter (2.5 × versus 3.5 × broad). In contrast to the original description, females have a smaller vulva that only covers one-third of the coxa, and the subanal plate is narrowly pointed rather than well-rounded. In males, the gonopore remains similar, but the anterior telopods differ by telopoditomere 4 with crenulated teeth. The immovable fingers of posterior telopods of Thai specimens are slender with 11–13 crenulated teeth, whereas those of the type specimens bear 11. Overall, the Thai specimens show consistent differences in body size, colour pattern, tegument texture, setation, legs, and telopod morphology, suggesting large intraspecific variation from the originally described population.
Despite this obvious variation, the male anterior and posterior telopods, the principal species-diagnostic structures in Zephronia, are indistinguishable between the Thai and Lao material. The Thai sequences cluster with the topotypic sequence MK330977 with maximal support (BS = 100, PP = 1.00) at a divergence of 4.88–5.95%, below the lowest interspecific distance recovered in this study (8.68%). We therefore treat the Thai population as a geographically divergent population of Z. laotica, while acknowledging that denser sampling in Laos and nuclear markers may reveal cryptic species-level structure.
Distribution and habitat.
Zephronia laotica is currently recorded only from the lower northeastern region of Thailand, specifically Si Sa Ket Province (Fig. 24). This species is typically found during the daytime in agricultural habitats such as durian orchards and rubber plantations. Specimens from durian orchards were found buried just below the soil surface, while those from rubber plantations were observed living on the surface beneath the leaf litter or decayed wood (Fig. 7J, K).
Zephronia tamarindina
Wilaisorn & Srisonchai sp. nov.
4B7A84C4-3772-5086-B481-52A2BB679763
https://zoobank.org/8165DAE1-E044-451A-9F0A-412857B3BDA0
Figs 1, 12–16, 22E, F, 23K–O, 24
Figure 12.
Photograph of live specimens of Zephronia tamarindina sp. nov. and habitats. A–F. Paratypes (MZKKU); G, H. Dipterocarp forest at the type locality. Scale bars: 5.0 mm.
Figure 16.
Zephronia tamarindina sp. nov., ♂ paratype (MZKKU) — SEM. A–C. Overview of telopods (anterior, posterior, and ventral views, respectively); D. Crenulated teeth of posterior telopods, posterior view; E. Anterior telopod, ventral view; F. Crenulated teeth of anterior telopods; G. Sclerotised spots on immovable finger of posterior telopod, sublateral view; H. Inner horns, anterior view. Abbreviations: cr-t = crenulated teeth, ml = membranous lobe, scl-s = sclerotised spots. Scale bars in millimetres.
Type specimens.
Holotype • ♂ (MZKKU-MYR0021); Thailand, Phetchabun Province, Bueng Sam Phan District, Nimit Sat Cha Tham Temple; 15°49'16.8"N, 100°55'03.9"E; ca 204 m a.s.l.; 3 September 2023; leg. C. Wilaisorn and MZKKU students. Paratypes. • 4 ♂♂ 4 ♀♀ (MZKKU-MYR0022); same data as for holotype; • 1 ♂ 1 ♀ (CUMZ-MYR0041); same data as for holotype.
Diagnosis.
The position of the Tömösváry’s organ located at the brim rather than inside the antennal groove (Fig. 13B, C), identifies Z. tamarindina sp. nov. as a member of the Zephronia s.s. species group. Z. tamarindina sp. nov. has an orangish brown body colour in adults and olive-greenish brown colour in juveniles, and differs from all other Zephronia s.s. species by the following combination of characters: in the anterior telopods, the process of telopoditomere 2 is broad and only slightly shorter than the combined length of telopoditomeres 3 and 4 (Figs 16C, 23K, 23M); telopoditomere 3 of the anterior telopods is distinctly widened (Figs 16C, 16F–H, 23K–M); and in the posterior telopods, telopoditomere 4 is strongly curved toward the immovable finger (Figs 16A–D, 23N, 23O). Males possess a conspicuous membranous process on the coxa of leg-pair 2 (Fig. 15B), a feature absent in all species except males of Z. enghoffi, Z. golovatchi and Z. sukhothaiensis. Z. tamarindina sp. nov. can be distinguished from the first two species by having only one row of marginal bristles in the midbody endotergum (two rows in Z. enghoffi and Z. golovatchi), and by the tip of the longest bristle being only half the length of the outer area (Fig. 22E, F), whereas in Z. enghoffi and Z. golovatchi the longest bristles project beyond the posterior margin. Z. tamarindina sp. nov. differs from Z. sukhothaiensis in the process of telopoditomere 2 of posterior telopods longer than telopoditomere 3+4 (while that of Z. sukhothaiensis is slightly shorter). Genetic divergence of COI sequences between Z. tamarindina sp. nov. and other Zephronia species ranged from 10.81 to 22.07%.
Figure 13.
Zephronia tamarindina sp. nov., ♂ paratype (MZKKU) — SEM. A. Collum, dorsal view; B. Head, anterior view; C. Antenna, lateral view; D. Tömösváry’s organ; E, F. Apical cones, lateral view; G, J. Gnathochilarium, anterior and ventral views, respectively; H. Sensory cones on inner palpi, ventral view; I. Sensory cones on central pad, ventral view; K. Epipharynx, ventral view; L. Right mandible, mesal view. Abbreviations: 3it = 3-combed inner tooth, co = condylus, Cp = central pad, ct = central tooth, et = external tooth of epipharynx, Et = external tooth of mandible, Ia = inner area, il = incisura lateralis, ip = inner palpi, ll = lamellae linguales, me = mentum, mp = molar plate, o = ommatidia, pl = pectinate lamellae, rsp = row of spines, sc = sensory cone, st = stipites, t = Tömösváry’s organ. Scale bars in millimetres.
Figure 15.
Zephronia tamarindina sp. nov., ♂ paratype (MZKKU), ♀ paratype (MZKKU) — SEM. A. Legs 1; B. Legs 2 with gonopores; C. Leg 2 with vulvae; D. Midbody legs (arrow points to femoral ridge); E. Small triangular spines on femur; F. Coxal process on midbody legs. Abbreviation: bu = bursa, cx = coxa, fe = femur, Mp = membranous process, op = operculum, po = postfemur, pre = prefemur, rdg = femoral ridge, st-pl = stigmatic plate, ta = tarsus, ti = tibia. Scale bars in millimetres.
Description.
Measurements. Male holotype; body length = 18.6 mm; width (broadest), of thoracic shield = 9.5 mm, of tergite 7 = 10.5 mm; highest of thoracic shield = 6.1 mm, of tergite 7 = 7.8 mm. Males: body length = 15.0–22.5 mm; width (broadest), of thoracic shield = 7.3–11.7 mm, of tergite 7 = 7.5–12.3 mm; highest of thoracic shield = 5.8–7.6 mm, of tergite 7 = 6.9–8.8 mm. Females: body length = 14.8–26.2 mm; width (broadest), of thoracic shield = 7.1–12.6 mm, of tergite 7 = 6.6–13.7 mm; highest of thoracic shield = 4.8–8.7 mm, of tergite 7 = 8.8–10.0 mm.
Colouration (Fig. 12A–F). Live adult specimens with orangish brown body colour, juveniles olive-greenish brown. Head and collum olive green. Thoracic shield and tergites brown, with pale brown posterior bands (juveniles with two pale yellow rectangular dorsal patches per tergite); paratergites olive green or orangish brown. Roll-up form with a dark brown stripe on dorsal surface of tergites. Anal shield orangish brown with pale posterior brown band. Antenna green. Legs greenish brown. Venter pale brown. Specimens preserved in 95% ethanol changed to dark brown and some yellowish brown after 1.5 years of preservation.
Head (Fig. 13B–D). Trapeziform; broad; concave dorso-posteriorly; densely setose anteriorly, especially mouthparts. With 103–115 ommatidia (ocelli). Aberrant ommatidium situated at brim of antennal groove. Tömösváry’s organ separated from eye field and located between base of antenna and ommatidia. No sclerotised ridge between antennal groove and ommatidia.
Antennae (Fig. 13B, C, E, F). Apparently short and stout, emerging from sides of the head, covered by short setae; last antennomere reaches back posteriorly to leg pair 2. Lengths of antennomeres in descending order: 6 > 5 = 4 > 3 = 2 = 1. Antennomere 6 slightly flat, axe-shaped; with sensilla basiconica around apical disc. Apical disc with 65–88 apical cones in males, 55–67 apical cones in females.
Epipharynx (Fig. 13K). Apically with a single triangular central tooth (ct); with a conspicuous long and slender inner tooth mesally; inner area with a single row of triangular fringed spines (rsp); outer area with several pointed and long external teeth (et).
Gnathochilarium (Fig. 13G–J). Lamellae linguales (ll) oval; apically concave; with dense and long setae. Central pads (cp) modified; with two types of sensory cones (sc); first small, without tubercle apically, second larger with a concave pad apically containing a single internal tubercle. Stipites (st) large, with dense and long setae; located laterally to lamellae linguales. Mentum (me) broad, fused; with dense setae. Lateral palpi inconspicuous. Inner palpi (ip) with numerous sensory cones (sc); located in single field, each cone concave apically and containing a single internal tubercle.
Mandibles (gnathal lobe) (Fig. 13L). With single undivided external tooth (Et) and 3-combed inner tooth (3it). With 5–6 rows of pectinate lamellae (pl). Inner area (Ia) with several rows of small slender teeth. Molar plate (mp) relatively flat, with shallow fringe. Condylus (co) conspicuous, apically with two ridges.
Tegument (Figs 12A–F, 14). Dull; collum, thoracic shield, tergites and anal shield covered by golden setae; each seta located in a small pit. Tergites and anal shield sparsely setose anteriorly and densely setose posteriorly.
Figure 14.
Zephronia tamarindina sp. nov., ♂ paratype (MZKKU), ♀ paratype (MZKKU) — SEM. A–C. Surface of midbody tergite, all in dorsal views (overview, anterior margin, surface, respectively); D. Subanal plate; E. Anal shield, underside, ventral view; F. Locking carinae; G. Surface of anal shield; H. First pleurite; I. Midbody pleurite. Scale bars in millimetres.
Collum (Fig. 13A). Subsemicircular; lateral margin with a few long setae.
Thoracic shield. Anterior margin with a shallow canal covered by numerous long setae; with 5–9 conspicuous keels.
Midbody tergite (Fig. 14A–C). Dorso-anterior margin with a row of oval circular impressions and numerous small tubercles. Inner area with a shallow groove; separated from anterior margin by a row of crenate barriers. Tips of paratergites projected posteroventrad.
Anal shield (Fig. 14E–G). Slightly sexually dimorphic; females well-rounded, males rectangular and slender. Anteriorly with a row of circular impressions and numerous small tubercles. Inner area with a shallow groove; separated from margin by a row of crenate barriers. Underside with a dark locking carina; as long as those of tergites. Densely setose on both underside and upperside.
Endotergum of thoracic shield and midbody tergite (Fig. 22E, F). Thoracic shield slightly different from midbody tergite. Posterior margin (pm) of both thoracic shield and midbody tergite flat, unmodified. Outer area (oa) of both thoracic shield and midbody tergite with small denticles. Marginal bristles of both thoracic shield and midbody tergite arranged in one row; bristle quite short; tips of longest bristles half-length of outer area and not reaching to posterior margin. Middle area (ma) of thoracic shield with a row of oval cuticular impressions (cp); distance between each impression as half as the length of individual diameter. Middle area of midbody tergite with a row of cuticular impressions; distance between each impression as long as individual diameter. Inner area (ia) of thoracic shield and midbody tergite with a few setae.
Pleurite (laterotergite) (Fig. 14H, I). Densely setose. First pleurite triangular; boomeranglike; reaching towards paratergite. Pleurite 2 wider than pleurite 1; tip obtuse. Pleurites 3–12 rectangular.
Subanal plate of female (Fig. 14D). Densely setose; wide; triangular; tip truncated.
Stigmatic plates (Fig. 15A). First stigmatic plate subtriangular; quite slender; flat antero-posteriorly; apex round, curving towards coxa. Second stigmatic plate in both sexes swollen; weakly curved.
Legs (Fig. 15). All podomeres densely setose. Coxa (cx) large; as long as length of prefemur (pre); first and second leg-pairs without coxal process; leg-pairs 3–21 with conspicuous processes. Prefemur stout; with short ridge (rdg); apico-mesally without projection. Femur (fe) wide and long, 1.5 × longer than prefemur; with conspicuous ridge; apico-mesally with a small projection; mesal margin dentate, with 6–8 small triangular microscopic spines (sp). Postfemur (po) and tibia (ti) short. Tarsus (ta) of midbody legs long and slender, as long as length of femur+postfemur; first two leg-pairs without an apical spine; leg-pair 1 with two or three ventral spines; leg-pair 2 with four or five ventral spines; leg-pair 3 with 6–10 ventral spines and one or two apical spines; leg pair 4 with 8–10 ventral spines and two or three apical spines; leg pairs 5–19 with 8–11 ventral spines and 3–5 apical spines; leg pair 20 and 21 with 7–9 ventral spines and three apical spines. In leg 10, femur 1.5 ×, tarsus 3 × longer than wide. Claw normal, with small notch at base.
Male sexual characters (Fig. 15B). Gonopore quite small; covered by a divided, triangular sclerotised plate. Apical part of coxa 2 with membranous process (Mp).
Anterior telopods (Figs 16A, 16C, 16F–H, 23K–M). Consisting of four telopoditomeres. First telopoditomere conspicuous; rectangular; longer than wide. Telopoditomere 2 large. Process of telopoditomere 2 (= immovable finger) broad; only slightly shorter than combination of telopoditomeres 3 and 4 (= movable finger); clearly seen in posterior view, strongly curved toward movable finger; inner margin with a single membranous lobe and numerous sclerotised spots (scl-s). Telopoditomere 3 wide; 2 × longer than telopoditomere 4; clearly demarcated from telopoditomere 4 by shallow suture; inner margin with single inconspicuous spine; apically with six or seven crenulated teeth (cr-t). Telopoditomere 4 very short; tip obtuse, with two spines. All telopoditomeres densely setose, except for basal part of telopoditomere 1 and of immovable finger of telopoditomere 2.
Posterior telopods (Figs 16A–E, 23N, 23O). Consisting of four telopoditomeres. First telopoditomere broad; slightly wider than long. Telopoditomere 2 large. Process of telopoditomere 2 (= immovable finger) long; 2 × longer than wide; longer than a combination of telopoditomeres 3 and 4 (= movable finger); apically round; slightly curved; inner margin with two membranous lobes (ml) and numerous conspicuous sclerotised spots (scl-s). Telopoditomere 3 long and slender; 2.5 × longer than wide; with a large membranous ledge and single long spine at inner margin; posteriorly with a row of 14–20 crenulated teeth (cr-t). Telopoditomere 4 short; 3 × shorter than telopoditomere 3; twice as long as wide; strongly curved toward the immovable finger; inner margin with two long spines located on a membranous ledge. Telopoditomere 1 covered by long setae. Anterior surface of telopoditomere 2 with a few setae but glabrous in posterior one. Inner margin of immovable finger and telopoditomere 3 sparsely setose. Telopoditomere 4 glabrous. Inner horns densely setose; swollen at base, slightly attenuate near tip.
Female sexual characters (Fig. 15C). Vulva large; sparsely setose; covering almost half of coxa; located at mesal margin; extending mesally to base of prefemur. Operculum (op) large; rectangular; mesal margin slightly concave; tip round. Bursa (bu) fused; heart-like; separated from operculum by a narrow triangular groove. Apical part of coxa 2 without coxal process.
Remarks.
The variation in colouration of paratergites was observed, with most specimens exhibiting an olive green colour, while some appeared orangish brown. Juveniles and smaller individuals typically showed olive greenish-brown colouration with rectangular patches on tergites. A distinctive feature of this species is the conspicuous triangular membranous process present on the coxae of male leg-pair 2 (Fig. 15B).
Distribution and habitat.
Zephronia tamarindina sp. nov. is currently known only from its type locality in Phetchabun Province and is thus considered endemic to this area (Fig. 24). The species was encountered during daytime on a rainy day within a dipterocarp forest, characterised by limestone terrain (Fig. 12G, H). Most specimens were observed moving on the ground amid gravel with sparse leaf litter.
Etymology.
The name is an adjective that derives from Tamarindus (tamarind), an important fruit cultivated in Phetchabun Province, the type locality. The name is treated as a feminine adjective in reference to the species body colouration, which changes from pale olive green in juveniles to a darker orangish brown in adults, resembling the ripening process of tamarind fruit from green to brown.
Zephronia triforma
Wilaisorn & Srisonchai sp. nov.
49AC5F67-AB78-5D73-AB8B-52D798D5B81D
https://zoobank.org/1B0E385B-F7DC-4EBF-9DC5-18F8D6652244
Figs 1, 17–21, 22G, H, 23P–T, 24
Figure 17.
Photograph of live specimens of Zephronia triforma sp. nov. and habitats. A, D, G. Male paratypes (MZKKU); B, E, H. Female paratypes (MZKKU); C, F, I. Live specimens of a population from Nakhon Sawan Province (MZKKU); J. Dipterocarp forest at the type locality; K. Dry deciduous forest at Nakhon Sawan sampling area. Scale bars: 5.0 mm.
Figure 21.
Zephronia triforma sp. nov., ♂ paratype (MZKKU) — SEM. A–C. Overview of telopods (anterior, posterior, and ventral views, respectively); D. Crenulated teeth of posterior telopods, posterior view; E. Sclerotised spots on immovable finger of posterior telopod, sublateral view; F. Anterior telopod, ventral view; G. Inner horns, anterior view. Abbreviations: cr-t = crenulated teeth, ml = membranous lobe, scl-s = sclerotised spots. Scale bars in millimetres.
Type specimens.
Holotype • ♂ (MZKKU-MYR0023); Thailand, Phitsanulok Province, Wat Bot District, Ban Nam Kob; 16°59'43.6"N, 100°23'34.0"E; ca 95 m a.s.l.; 6 August 2024; leg. C. Wilaisorn and MZKKU students. Paratypes. • 29 ♂♂ 25 ♀♀ (MZKKU-MYR0024), same data as for holotype; • 1 ♂ 1 ♀ (CUMZ-MYR0042); same data as for holotype; • 1 ♂ 1 ♀ (NHMUK); same data as for holotype; • 1 ♂ 1 ♀ (NHMD); same data as for holotype; • 1 ♂ 1 ♀ (NHMW); same data as for holotype; • 2 ♂♂ 2 ♀♀ (ZFMK); same data as for holotype.
Additional material.
• 13 juveniles (MZKKU), same data as for holotype; • 29 ♂♂, 13 ♀♀ (MZKKU); Thailand, Phitsanulok Province, Wat Bot District, Khao Bo Ma Viewpoint; 17°18'20.3"N, 100°26'29.2"E; ca. 216 m a.s.l.; 10 July 2024; leg. C. Wilaisorn, R. Srisonchai and MZKKU students; • 7 ♂♂ 4 ♀♀ (MZKKU); Thailand, Nakhon Sawan Province, Takhli District, Buddhawajana Dhamma Retreat; 15°17'51.7"N, 100°22'24.6"E; ca 70 m a.s.l.; 31 July 2023; leg. C. Wilaisorn, R. Srisonchai, and MZKKU students.
Diagnosis.
The position of the Tömösváry’s organ is located at the brim rather than inside the antennal groove (Fig. 18B, C), placing Z. triforma sp. nov. within the Zephronia s.s. species group. Z. triforma sp. nov. exhibits a distinctive range of live body colour patterns, forming three morphotypes: (1) males with greyish brown colouration and dark brown freckles, (2) females with reddish brown colouration, and (3) both sexes with a brownish emerald-green colouration. Beyond these colour traits, Z. triforma sp. nov. differs from other members of the Zephronia s.s. group by the following combination of characters: anterior telopods with the process of telopoditomere 2 broad; telopoditomere 4 very short with a tapering tip (Figs 21C, 21F, 23P–R); operculum with a concave mesal margin and a dull tip (Fig. 20C); endotergum with a flat, regular, posterior margin bearing two rows of marginal bristles, the longest bristles not projecting beyond the posterior margin, one row of circular cuticular impressions, and an inner area lacking setae (Fig. 22G, H). Genetic divergence between Z. triforma sp. nov. and other Zephronia species ranged from 10.81 to 22.83% based on 658 bp COI sequences.
Figure 18.
Zephronia triforma sp. nov., ♂ paratype (MZKKU) — SEM. A. Collum, dorsal view; B. Head, anterior view; C. Antenna, lateral view; D. Tömösváry’s organ; E, F. Apical cones, lateral view; G, J. Gnathochilarium, anterior and ventral views, respectively; H. Sensory cones on inner palpi, ventral view; I. Sensory cones on central pad, ventral view; K. Epipharynx, ventral view; L. Right mandible, mesal view. Abbreviations: 3it = 3-combed inner tooth, co = condylus, Cp = central pad, ct = central tooth, et = external tooth of epipharynx, Et = external tooth of mandible, Ia = inner area, il = incisura lateralis, ip = inner palpi, ll = lamellae linguales, me = mentum, mp = molar plate, o = ommatidia, pl = pectinate lamellae, rsp = row of spines, sc = sensory cone, st = stipites, t = Tömösváry’s organ. Scale bars in millimetres.
Figure 20.
Zephronia triforma sp. nov., ♂ paratype (MZKKU), ♀ paratype (MZKKU) — SEM. A. Legs 1; B. Legs 2 with gonopores; C. Leg 2 with vulvae; D. Midbody legs (arrow points to femoral ridge); E. Phoretic deutonymphs of an unknown mite; F. Small triangular spines on femur. Abbreviation: bu = bursa, cx = coxa, fe = femur, op = operculum, po = postfemur, pre = prefemur, rdg = femoral ridge, st-pl = stigmatic plate, ta = tarsus, ti = tibia. Scale bars in millimetres.
Description.
Measurements. Male holotype; body length = 17.9 mm; width (broadest), of thoracic shield = 10.6 mm, of tergite 7 = 11.1 mm; highest of thoracic shield = 5.8 mm, of tergite 7 = 6.5 mm. Males: body length = 15.2–26.2 mm; width (broadest), of thoracic shield = 8.7–11.03 mm, of tergite 7 = 9.2–15.2 mm; highest of thoracic shield = 5.2–8.7 mm, of tergite 7 = 5.3–9.7 mm. Females: body length = 18.2–30.8 mm; width (broadest), of thoracic shield = 8.9–15.2 mm, of tergite 7 = 9.6–15.9 mm; highest of thoracic shield = 5.4–9.2 mm, of tergite 7 = 5.1–11.1 mm.
Colouration (Fig. 17A–I). Living specimens of Phitsanulok population of greyish brown colour with dark brown freckles in males; dark reddish-brown colour without freckles in females. Head and collum dark brown. Thoracic shield and tergites greyish brown in males, dark reddish-brown in females. Both sexes with dark brown posterior bands on tergites, and with a dark stripe on middle area of tergites, clearly seen when rolled up. Anal shield orangish brown on posterior margin. Antenna and legs green. Venter pale brown. Specimens in 95% ethanol changed to dark brown after 1.5 years of preservation.
Living specimens of Nakhon Sawan population with a brownish emerald-green body. Head and collum brownish emerald green. Thoracic shield and tergites dark green with dark brown posterior. Anal shield emerald green with pale brown on posterior margin. Antenna and legs green. Venter pale brown. Specimens in 95% ethanol faded to dark brown after 1.5 years of preservation.
Head (Fig. 18B–D). Trapeziform, broad, round; densely setose anteriorly especially mouthparts. With 88–112 ommatidia (ocelli). Aberrant ommatidium situated at brim of antennal groove. Tömösváry’s organ separated from eye field and located between base of antenna and ommatidia. No sclerotised ridge between antennal groove and ommatidia.
Antennae (Fig. 18B, C, E, F). Short and sturdy, emerging from both sides of head, covered by noticeable long setae; last antennomere reaches back posteriorly to leg pair 2. Lengths of antennomeres in descending order: 6 > 5 = 4 > 3 = 2 > 1. Antennomere 6 flattened, axe-shaped; with sensilla basiconica around apical disc. Apical disc shallowly concave; with 48–88 apical cones in males, and 43–77 apical cones in females.
Epipharynx (Fig. 18K). Apically with a single obtuse central tooth (ct); in the middle with a conspicuous and swollen inner tooth; inner area with a single row of triangular fringed spines (rsp); outer area with several pointed and long external teeth (et).
Gnathochilarium (Fig. 18G–J). Lamellae linguales (ll) rounded, apically concave, densely setose. Central pads (Cp) modified, with two types of sensory cones (sc), first small without a tubercle apically, second larger with a concave pad apically containing a single internal tubercle. Stipites (st) large and thick, with densely long setae; located laterally to lamellae linguales. Mentum (me) broad and fused, densely setose. Lateral palpi inconspicuous. Inner palpi (ip) with numerous cylinder sensory cones (sc) located in single field, each cone concave apically and containing a single internal tubercle.
Mandibles (gnathal lobe) (Fig. 18L). With single undivided external tooth (Et) and 3-combed inner tooth (3it). With 6–7 rows of pectinate lamellae (pl). Inner area (Ia) with several rows of small, slender teeth. Molar plate (mp) relatively flat, with shallow fringe. Condylus (co) conspicuous; apically with two ridges.
Tegument (Figs 17A–I, 19). Dull; collum, thoracic shield, tergites and anal shield densely covered by golden setae; each seta emerged from a pit. Tergites and anal shield sparsely setose anteriorly and densely setose posteriorly. Posterior rim with bare setae on both dorsal and ventral sides.
Figure 19.
Zephronia triforma sp. nov., ♂ paratype (MZKKU), ♀ paratype (MZKKU) — SEM. A–C. Surface of midbody tergite, all in dorsal views (overview, anterior margin, surface, respectively); D. Subanal plate; E. Anal shield, underside, ventral view; F. Locking carinae; G. Surface of anal shield; H. First pleurite; I. Midbody pleurite. Scale bars in millimetres.
Collum (Figs 18A). Subsemicircular; lateral edges triangular, with sparse setae.
Thoracic shield. Anterior margin with shallow canal covered by numerous long setae. Phitsanulok population with 3–6 small keels. Nakhon Sawan population with 6–10 conspicuous keels.
Midbody tergite (Fig. 19A–C). Dorso-anterior margin with a row of circular impressions and numerous small tubercles. Inner area with a shallow groove, separated from anterior margin by a row of crenate barriers. Tips of paratergites projected posteroventrad.
Anal shield (Fig. 19E–G). Slightly sexually dimorphic; female anal shield well-rounded, males rectangular and slender. Anteriorly with a row of circular impressions and numerous small tubercles. Inner area with a shallow groove; separated from margin by a row of crenate barriers. Underside with a dark locking carina; twice as long as those of tergites. Densely setose on both underside and upperside.
Endotergum of thoracic shield and midbody tergite (Fig. 22G, H). Thoracic shield quite similar to midbody tergite. Posterior margin (pm) regularly flat. Outer area (oa) with several small denticles. Marginal bristles arranged in two rows, tips of longest bristles of Phitsanulok specimens two-thirds length of outer area (one-third in Nakhon Sawan specimens) and not projecting above margin. Middle area (ma) with a row of circular cuticular impressions (cp); distance between each impression twice as long as individual diameter in thoracic shield, and 3 × as long as individual diameter in midbody tergite. Cuticular impressions of thoracic shield shallower than those of midbody tergite. Inner area (ia) without tubercles or setae.
Pleurite (laterotergite) (Fig. 19H, I). Densely setose. First pleurite boomeranglike with pointed edge, reaching towards paratergite. Pleurite 2 widened. The remaining flat, rectangular.
Subanal plate of female (Fig. 19D). Densely setose; wide; semicircular; apical margin weakly concave, narrow.
Stigmatic plates (Fig. 20A). First stigmatic plate quite slender, flat ante-posteriorly; apex broadly round, curved towards coxa. Second stigmatic plate in both sexes broad, weakly curved.
Legs (Fig. 20). All podomeres densely setose. Coxa (cx) large, as long as length of prefemur (pre); first and second leg-pairs without coxal process; leg-pairs 3–21 with large and slightly serrated processes. Prefemur plump; with short ridge (rdg); apico-mesally with a very weak projection; mesal margin with one or two small triangular microscopic spines (sp). Femur (fe) prolonged; 1.5 × longer than prefemur; with conspicuous long ridge; apico-mesally with a strong projection; mesal margin dentated, with 10–12 small triangular spines. Postfemur (po) and tibia (ti) short. Tarsus (ta) of midbody legs long and slender, as long as length of femur+postfemur; first two leg-pairs without an apical spine; leg-pair 1 with two or three ventral spines; leg-pair 2 with four or five ventral spines; leg-pair 3 with 5–7 ventral spines and 1–3 apical spines; leg pair 4 with 7–10 ventral spines and three or four apical spines; leg pairs 5–19 with 9–12 ventral spines and 3–5 apical spines; leg pair 20 and 21 with 7–10 ventral spines and two or three apical spines. In leg 10, femur 1.5 ×, tarsus 3 × longer than wide. Claw normal; with notch at base.
Male sexual characters (Fig. 20B). Gonopore surrounded by long setae; covered with a divided, triangular sclerotised plate. Apical part of coxa 2 without membranous process.
Anterior telopods (Figs 21A, 21C, 21F, 21G, 23P–R). Consisting of four telopoditomeres. First telopoditomere broad; slightly longer than wide. Telopoditomere 2 large. Process of telopoditomere 2 (= immovable finger) broad; shorter than combination of telopoditomeres 3 and 4 (= movable finger); located posteriorly; clearly seen in posterior view; tapering apically; strongly curved toward movable finger; inner margin with a membranous lobe and numerous sclerotised spots (scl-s). Telopoditomere 3 slender; almost twice as long as telopoditomere 4; demarcated from telopoditomere 4 by weak suture; inner margin with single conspicuous spine; apically with 2–5 crenulated teeth (cr-t). Telopoditomere 4 very short; tapering tip, with two long spines. All telopoditomeres covered by long sparse setae, except for basal part of telopoditomere 1 and tip of telopoditomere 2.
Posterior telopods (Figs 21A–E, 23S, 23T). Consisting of four telopoditomeres. First telopoditomere rectangular; longer than wide. Telopoditomere 2 large and stout. Process of telopoditomere 2 (= immovable finger) long and slender, 2.5 × longer than wide; slightly longer than a combination of telopoditomeres 3 and 4 (= movable finger); weakly tapering apical; slightly curved; inner margin with two membranous lobes (ml) and numerous conspicuous sclerotised spots (scl-s). Telopoditomere 3 long; 3 × longer than wide; with a large membranous ledge and single long spine at inner margin; posteriorly with a row of 12–17 crenulated teeth (cr-t). Telopoditomere 4 short; 4 × shorter than telopoditomere 3; twice as long as wide, slightly tapering apically; inner margin with two long spines located on membranous ledge. Telopoditomere 1 and 2 mostly covered by setae on anterior surface, glabrous on posterior surface. Telopoditomere 3 sparsely setose. Telopoditomere 4 glabrous. Inner horns sparsely setose; base wide; sharp-edged tips; slightly curved posteriorly.
Female sexual characters (Fig. 20C). Vulva large, sparsely setose; covering almost half of coxa; located mesoventrally; extending mesally to base of prefemur. Operculum (op) slender; rectangular; with slightly concave mesal margin; tip of operculum dull. Bursa (bu) large; fused; separated from operculum by triangular groove. Apical part of coxa 2 without coxal process.
Remarks.
Notable sexual dimorphism is observed in the Phitsanulok specimens, in which adult males possess a greyish brown body with dark brown freckles, whereas adult females exhibit a reddish-brown body lacking freckles. Specimens from Nakhon Sawan Province differ in body colouration (brownish emerald-green) from those of Phitsanulok Province. The two populations also show slight morphological variation in marginal bristles of endotergum, the Phitsanulok specimens having bristles reaching two-thirds the length of the outer area, while those from Nakhon Sawan reach only one-third. These differences are accompanied by moderate but sub-specific genetic differentiation between the two populations (pairwise distances 5.02–5.63%), which remains well below the lowest interspecific distance recovered here (8.68%). Specimens from the type locality (Ban Nam Kob in Phitsanulok Province) were heavily infested with numerous small, white, phoretic deutonymphs of an unidentified mite, concentrated on the ventral surface, particularly legs (Fig. 20D, E).
Distribution and habitat.
Zephronia triforma sp. nov. is currently known only from the upper central region of Thailand, specifically Nakhon Sawan and Phitsanulok Provinces (Fig. 24). The specimens of populations from Phitsanulok Province were found during the daytime in dipterocarp forests, typically walking on the sandstone or sometimes hiding under the leaf litter (Fig. 17J). The individuals of the population from Nakhon Sawan Province were found in a dry deciduous forest characterised by sparse undergrowth, leaf litter, and rocky limestone terrain (Fig. 17K).
Etymology.
The species name is a Latin compound noun derived from tri- (three) and forma (form), referring to the three distinct morphotypes observed in the material used to describe the new species.
Discussion
Species delimitation and the barcoding gap in Thai Zephronia
An integrative approach combining both morphological and molecular information led to the discovery of two new giant pill-millipede species, viz., Z. tamarindina sp. nov. and Z. triforma sp. nov., and also the first records of Z. dawydoffi and Z. laotica in Thailand. All specimens of the latter two species closely match the original descriptions; however, morphological variations were observed and are documented here with SEM images. Both new species are assigned to the genus Zephronia based on the presence of diagnostic genus-specific characters, including axe-shaped antennae, the number of apical spines on the tarsi, and the distinctive morphology of the male telopods (Wesener 2016). Morphological and COI barcoding trees further indicate that the two new record species are closely related to Z. siamensis and Z. ovalis. These taxa share several diagnostic features, such as the presence of two colour patches on the tergites and a modified posterior margin of endotergum (Golovatch et al. 2012; Srisonchai et al. 2021; Srimongkol et al. 2026). In addition, the new species exhibits characters commonly observed in other congeners, including the position of the Tömösváry’s organ outside the antennal groove, a flat and regular posterior margin on the endotergum with 1–2 rows of marginal bristles, tips of the longest bristles not protruding over the posterior margin, and the absence of apical spines only on the first two leg pairs. Morphological and molecular evidence clearly place both species within Zephronia s.s. (Fig. 1). However, Z. tamarindina sp. nov. can be distinguished from its closely related congeners by the unique shape of anterior telopods (strongly curved in the process of telopoditomere 2 and widening telopoditomere 3, as well as a strongly curved telopoditomere 4 of posterior telopods, and a large membranous process on the coxa of male leg-pair 2. Although Z. enghoffi, Z. golovatchi and Z. sukhothaiensis also possess a similar membranous process in male leg pair 2 (Srisonchai et al. 2021; Srimongkol et al. 2026), Z. enghoffi and Z. golovatchi differ from Z. tamarindina sp. nov. in endotergal characters (bristle number and length), Z. sukhothaiensis differs in the length of process of telopoditomere 2 of posterior telopods, and the three species show genetic differences from Z. tamarindina sp. nov. (Fig. 1).
In Zephronia, species identification based solely on telopod morphology can be challenging, as interspecific variation in this structure is sometimes subtle and not always sufficient for clear species delimitation. Therefore, additional morphological characters, in combination with molecular evidence, are required to achieve reliable species identification.
Zephronia triforma sp. nov. is notable for its sexually dimorphic colouration within the Phitsanulok population, in which the males exhibit randomly distributed dark spots on a greyish-brown body, while females are reddish brown. This colour pattern differs markedly from that observed in both sexes of the Nakhon Sawan population, which display a uniform brownish emerald-green colouration and from all other known Zephronia species, with the exception of the spotted morph of Z. macula. Nevertheless, Z. triforma sp. nov. can be readily distinguished from Z. macula by several characters, including differences in live body colouration (Z. macula greenish to reddish brown vs. Z. triforma sp. nov. greyish brown), and clear genetic divergence (Srisonchai et al. 2024, Fig. 1).
In this study, DNA barcoding proved to be a highly effective tool for species delimitation (Hebert et al. 2003). In the case of the Phitsanulok population of Z. triforma sp. nov., barcoding reliably matched females with males of the same species and confirmed species identity across distinct morphotypes, including those from Nakhon Sawan and Phitsanulok populations. The COI barcoding sequences from these two populations formed two clearly separated subclades in both BI and ML trees, each with strong support (BS = 95, PP = 1.00). Despite this phylogenetic separation, the maximum intraspecific genetic distance between the populations was only 5.63%. A similar pattern has been reported for the green and spotted morphs of Z. macula, which differ markedly in body colour and patterns, yet exhibit a maximum intraspecific divergence of approximately 5% (Srimongkol et al. 2026). Likewise, Srisonchai et al. (2021) documented colour variation in Z. phrain relative to its type specimen, although no genetic divergence data between morphotypes were provided.
In our study, the COI genetic distance between geographic populations of Z. triforma sp. nov. (5.02–5.63%) approaches, but remains below, the minimum interspecific distance observed between Z. siamensis and Z. dawydoffi (8.68%). High intraspecific sequence divergence is relatively common in giant pill-millipedes, likely driven by low dispersal ability and prolonged geographic isolation (Wesener et al. 2010; Bhansali and Wesener 2022). Because the two Z. triforma sp. nov. populations display identical diagnostic characters in the structure of the male telopods, we treat this divergence as population-level. In contrast, Z. dawydoffi and Z. siamensis display distinct, non-overlapping differences in telopod morphology, confirming their separation despite the narrow barcoding gap. In giant pill-millipedes, interspecific genetic distances commonly used for species delimitation typically range from 8–21% (Donworth and Wesener 2024; Srisonchai et al. 2024). In the present study, the observed range was slightly broader (8.68–25.27%), most likely reflecting the inclusion of more closely related taxa. This pattern aligns with previous findings of Zephronia and related genera (Golovatch et al. 2012; Wesener 2019; Rosenmejer et al. 2021; Bhansali and Wesener 2022; Srisonchai et al. 2024; Srimongkol et al. 2026). However, the discovery of additional closely related species in future may further reduce the lower boundary of observed interspecific distances (Bhansali and Wesener 2022). We emphasise that species delimitation here is morphology-primary and COI-corroborative, no fixed genetic threshold was applied.
The relatively large interspecific genetic distances (8.68–24.89%) between the two newly described species, the two newly recorded species from Thailand, and their congeners (Sphaerobelum spp., Prionobelum spp., Cryxus, and Zephronia spp. from Southeast Asia) nonetheless highlight the evolutionary and biogeographical processes that have shaped diversity of Thai giant pill-millipedes (Wesener 2019). Despite this, interpretations of deep evolutionary relationships remain limited by reliance on a single-locus marker. Although the phylogenetic analyses placed all four species within the Zephronia s.s. group, resolution of internal nodes within Zephronia and Sphaerobelum was generally poor, and instances of non-monophyly were observed (Fig. 1). Weak support at deep nodes indicates that the current dataset is insufficient to fully resolve early divergences, a limitation also noted in previous studies (Hennen et al. 2022; Srisonchai et al. 2024; Srikampha et al. 2025). While recent phylogenetic relationships are well supported, deeper evolutionary splits remain uncertain and should be treated cautiously (Philippe et al. 2011).
Generic limits within Zephroniinae
Molecular data based on the COI barcoding region show that traditional generic boundaries within Zephroniinae are problematic. Specifically, Zephronia is non-monophyletic, with species like Z. hui, Z. medogensis, and Z. zhouae nesting within Sphaerobelum. Together with the close placement of Prionobelum and Cryxus, these trees show that traditional diagnostic traits such as telopod morphology and the position of the Tömösváry's organ have evolved independently across different lineages or show greater structural variation than previously recognised. While single-locus COI data cannot formally revise the subfamily classification, they clearly demonstrate that morphology-based generic limits require thorough reconsideration. To establish a stable classification for Zephroniinae, future studies incorporating multi-locus markers, more conserved nuclear regions, and genomic-scale data combined with more comprehensive taxon sampling across Southeast Asia could improve the resolution within the genus or family (Wiens and Morrill 2011; Dietz et al. 2023). Pending such data, we retain the current generic assignments and refrain from proposing nomenclatural changes here.
Distribution and biogeography
Based on the distribution record obtained in this study, Z. tamarindina sp. nov. and Z. triforma sp. nov. appear to be restricted to the upper central region of Thailand. Z. tamarindina sp. nov. is currently known only from its type locality in Phetchabun Province, whereas Z. triforma sp. nov. has been recorded exclusively from Nakhon Sawan and Phitsanulok Provinces. Consequently, both species are considered endemic to the upper central region. Z. tamarindina sp. nov. exhibits a narrow distribution, similar to several other Thai species that are confined to their type localities, such as Z. chantaburiensis, Z. chrysomallos, Z. erawani, and Z. viridisoma (Fig. 24). By contrast, Z. triforma sp. nov. shows a distributional pattern more comparable to widely distributed species, including Z. macula, Z. panhai, Z. siamensis, Z. phrain, and Z. dawydoffi (Fig. 24), some of which occur over areas spanning 200–300 km (Srisonchai et al. 2024). Both new species inhabit similar habitats and microhabitats.
Zephronia dawydoffi, originally described from southern Cambodia (Ream, Sre Umbell; Kampot, Kampong Speu) (Attems 1953; Wesener 2016), is here recorded for the first time from northeastern Thailand, including Buri Ram and Khon Kaen Provinces, extending its known distribution by approximately 300–700 km northward (Fig. 24). Within Thailand, the species appears to be relatively widespread in several districts of Buri Ram Province but was recorded from only a single locality in Khon Kaen Province. This distribution pattern suggests a relatively broad and semi-continuous range from southern and central Cambodia to the lower and central parts of northeastern Thailand. The distribution appears to be mainly continuous, but it is likely structured by modest geographical features such as low mountain ranges, the Phnom Dangrek or Daegrêk ranges, which may act as partial barriers to dispersal. Consistent with a pattern of isolation by distance, these conditions may promote gradual population differentiation across areas (Attwood et al. 2008; Siriwut et al. 2015). This interpretation is further supported by the observed COI genetic divergence between Cambodian and Thai populations of 3.65–5.18% (mean 4.03%), which indicates the early stages of population structuring across the range. No material is available from the ca. 150–700 km separating the Thai populations from the type localities, and the possibility of a morphological cline therefore remains untested. A similar distributional pattern has been observed in Z. ovalis, which also has a relatively broad and largely continuous range across mainland Southeast Asia (Srimongkol et al. 2026). It suggests that widely distributed Zephronia taxa share similar dispersal restrictions and landscape-mediated population structuring due to these similar distribution patterns of the two species.
Zephronia laotica was originally reported from Champasak Province in southern Laos, on the east bank of the Mekong River, and in this study it was recorded from Si Sa Ket Province in northeastern Thailand, approximately 150–200 km from its type locality (Fig. 24). Both Z. dawydoffi and Z. laotica occur primarily in agricultural habitats, especially rubber plantations with fine soil, where they are found under leaf litter and decayed wood. This matches Wesener’s (2019) observation of Z. laotica inhabiting hotel gardens as effectively man-made plantation forests. Comparable habitat associations have also been reported in other arthropod groups, highlighting the role of human-altered environments in shaping contemporary distribution patterns (Monaghan et al. 2009; Seibold et al. 2019; de Vries et al. 2026). Nevertheless, the habitat preference of this species remains unclear. Although it is frequently recorded from anthropogenic environments, it also occurs in natural habitats (K. Srikampha, unpublished data). This suggests that Z. laotica may not be restricted to human-modified landscapes but may have originally been distributed in natural ecosystems, with its apparent association with disturbed habitats potentially reflecting sampling bias or recent ecological expansion.
This study increases the number of recognised Zephronia species in Thailand to 18, expanding the genus’s known range, particularly in northeastern and upper central Thailand. The steady discovery of new giant pill-millipede species since 2021 (e.g., Likhitrakarn et al. 2021; Srisonchai et al. 2021; Donworth and Wesener 2024) highlights Thailand’s exceptional yet still underexplored biodiversity. Given that Zephronia is a species-rich genus, these findings suggest the existence of additional, as-yet-undescribed species, especially within the country’s unexplored natural habitats. With continued research and broader field surveys, Zephronia is poised to become not only one of the key groups representing the diversity of Thailand’s millipede fauna, but also an important component of the Southeast Asian biodiversity hotspot.
Supplementary Material
Acknowledgements
This work was conducted as part of a series of small workshops on soil fauna surveys in the Chao Phraya and Mekong River basins, organised for undergraduate and graduate students in the Young Taxonomist program at Khon Kaen University. We are grateful to the curators of NHMW (Nesrine Akkari) and ZFMK (Thomas Wesener) for providing information on the type material for comparison with the newly collected specimens. We sincerely thank the Department of Biology, Faculty of Science, Khon Kaen University, for providing laboratory facilities throughout this study. We also thank the field assistants, students from Khon Kaen University Museum of Zoology (MZKKU) and local partners for their assistance with specimen collection and site access. We thank the staff of the Department of National Parks, Wildlife and Plant Conservation for their guidance during field surveys on soil fauna in the Chao Phraya River Basin areas. Special thanks are due to Khanet Srikampha for providing photographs of live specimens. We also acknowledge the constructive comments from reviewers and journal editors, which improved the quality of this work. Computational analyses were supported by the Cipres Science Gateway. Nisarat Tungpairojwong and Ruttapon Srisonchai jointly supervised this study and shared responsibility for the preparation, revision, and correspondence of the manuscript; Nisarat Tungpairojwong is listed as the single corresponding author in accordance with the journal’s submission requirements.
Citation
Wilaisorn C, Srisonchai R, Kutanan W, Tungpairojwong N (2026) Two new species and two new country records of the giant pill-millipede genus Zephronia Gray, 1832 from Thailand, based on integrative taxonomy (Diplopoda, Sphaerotheriida, Zephroniidae). ZooKeys 1294: 1–59. https://doi.org/10.3897/zookeys.1294.205518
Funding Statement
Fundamental Fund, Fiscal year 2024 (200596)
Additional information
Conflict of interest
The authors have declared that no competing interests exist.
Ethical statement
The animal ethic protocol was approved by the Institutional Animal Care and Use Committee of Khon Kaen University (No. IACUC-KKU-137/67).
Artificial Intelligence (AI) use
The authors accept full responsibility for the content of the manuscript, including the disclosure of any use of AI.
No AI tools were used in the preparation of this manuscript.
Funding
This work was supported by the Fundamental Fund, Fiscal year 2024 (200596).
Author contributions
Conceptualization: RS, NT; Methodology: CW, RS, WK, NT; Validation: WK, NT; Formal analysis: CW, RS; Investigation: CW, RS, NT; Resources: RS, NT; Data curation: CW; Writing-Original Draft: CW; Writing - Review & Editing: RS, WK, NT; Visualization: CW; Supervision: RS, NT; Project administration: RS, NT; Funding acquisition: NT.
Author ORCIDs
C. Wilaisorn https://orcid.org/0009-0001-3673-4167
R. Srisonchai https://orcid.org/0000-0002-7142-0999
W. Kutanan https://orcid.org/0000-0001-7767-1644
N. Tungpairojwong https://orcid.org/0000-0001-8135-4246
Data availability
The data underlying this article are available in the GenBank Nucleotide Database (https://www.ncbi.nlm.nih.gov/genbank/), and can be accessed with accession numbers listed in Table 1.
Supplementary materials
Supplementary information
This dataset is made available under the Open Database License (http://opendatacommons.org/licenses/odbl/1.0/). The Open Database License (ODbL) is a license agreement intended to allow users to freely share, modify, and use this Dataset while maintaining this same freedom for others, provided that the original source and author(s) are credited.
Chalintorn Wilaisorn, Ruttapon Srisonchai, Wibhu Kutanan, Nisarat Tungpairojwong
Data type
xlsx
Explanation note
Genetic divergences of cytochrome c oxidase subunit I (COI) sequence (uncorrected p-distances) within and among Zephronia species, and related genera (Sphaerobelum, Prionobelum, and Cryxus).
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Supplementary information
This dataset is made available under the Open Database License (http://opendatacommons.org/licenses/odbl/1.0/). The Open Database License (ODbL) is a license agreement intended to allow users to freely share, modify, and use this Dataset while maintaining this same freedom for others, provided that the original source and author(s) are credited.
Chalintorn Wilaisorn, Ruttapon Srisonchai, Wibhu Kutanan, Nisarat Tungpairojwong
Data type
xlsx
Explanation note
Genetic divergences of cytochrome c oxidase subunit I (COI) sequence (uncorrected p-distances) within and among Zephronia species, and related genera (Sphaerobelum, Prionobelum, and Cryxus).
Data Availability Statement
The data underlying this article are available in the GenBank Nucleotide Database (https://www.ncbi.nlm.nih.gov/genbank/), and can be accessed with accession numbers listed in Table 1.