Taxonomic Study of the Chalcidoid Wasps Sycoscapter Saunders (Hymenoptera: Pteromalidae) Associated with Monoecious Ficus in Taiwan, with Description of Four New Species

Abstract

As a prominent group of nonpollinating fig wasps widely distributed in the paleotropics, Sycoscapter Saunders has been subject to limited taxonomic attention. This study presents the first comprehensive taxonomic investigation of Sycoscapter wasps associated with five Taiwanese monoecious fig species, employing both molecular and morphological methods. Phylogenetic analyses using COI and COI+28S data revealed the presence of five species associated with monoecious figs in Taiwan and neighboring regions: Sycoscaptergajimaru (Ishii), Sycoscapterpiceoscapus Chou & Tzeng sp. nov., Sycoscapter monticola Chou & Tzeng sp. nov., Sycoscapterishiianus Chou & Tzeng sp. nov., and Sycoscapterlittoralis Chou & Tzeng sp. nov. Morphologically, these five Sycoscapter species possessed distinctive characteristics, including the male head shape, which distinguished them from related species. Furthermore, males of all five species exhibited rudimentary wing vestiges, commonly found in wasps associated with monoecious figs but absent in those associated with dioecious figs. Overall, this study enriches our understanding of chalcidoid fauna in Taiwan and provides insight into the mechanisms that sustain intricate ecosystems.

BACKGROUND

The obligate symbiosis between fig trees (Ficus L.) and chalcidoid wasps (Hymenoptera), especially Agaonidae and Pteromalidae, serves as a well-established model for exploring speciation and coevolution (Weiblen 2002; Borges 2015). In this context, the subtribe Sycoryctina (http://www.figweb. org; van Noort and Rasplus 2024) of Otitesellini in Pteromalidae is one of the most common groups interacting with figs and agaonid wasps in the paleotropics (Segar et al. 2012; Burks et al. 2022). Since female Sycoryctina wasps, as external exploiters, use their elongated ovipositors to extract resources from within figs for their offspring, the lengths of ovipositors must correspond to the fig-wall thicknesses (Tzeng et al. 2014). Consequently, they exhibit high host-specific speciation and contribute substantially to the tribe’s diversity (McLeish et al. 2010).

The genus Sycoscapter Saunders, one of the most diverse group of Sycoryctina, comprises 23 described species from Africa and Asia (Bouček 1988; Berg and Wiebes 1992; Segar et al. 2012). However, differentiating Sycoscapter from other genera within the same tribe has been complicated by changeable diagnostic characters. Consequently, Bouček (1988) suggested the concept of consolidating all genera into Sycoscapters.l. to resolve this ambiguity in Sycoryctini. Nevertheless, advancements in morphological analyses and molecular phylogeny have brought about the possibility of establishing a natural taxonomic system for Sycoryctini (Berg and Wiebes 1992; Segar et al. 2012). Presently, the genera synonymized by Bouček (1988) are reinstated and the diagnostic criteria for Sycoscapters.s. encompass the following: in females, the forewing features a “boot-like” stigma and robust hairs, with symmetric funicular segments; in males, mesonotum is fused with metanotum and propodeum, and the basitarsus of the hind leg remains unexpanded (Berg and Wiebes 1992; Segar et al. 2012; Pramanik and Dey 2019).

As a vital component of fig-wasp symbiosis, including interactions involving Sycoscapter, fig trees are key elements of tropical and subtropical ecosystems, encompassing approximately 750 described species (Berg and Corner 2005). Depending on the flower types in figs, Ficus species can be categorized as monoecious or functionally dioecious, with approximately half of all species falling into each category (Berg and Corner 2005; Cruaud et al. 2012; Gardner et al. 2023). Monoecious figs possess protogynous female and male flowers in each fig. Consequently, female flowers develop galls when oviposited, whereas the remainder form seeds through pollen transferred by the wasps. In contrast, functional dioecious figs allocate female flowers to distinct figs, with female figs containing fertile female flowers and male figs possessing male and infertile female flowers, which only form galls. Agaonid wasps associated with functional dioecious figs can lay eggs in the infertile female flowers of male figs but facilitate pollination in female figs without leaving offspring (Weiblen 2002). The coexistence of all flower types in a monoecious fig creates mixed layers of developing seeds and galls, promoting diverse and complex fig-wasp communities (Kerdelhué and Rasplus 1996). Moreover, as an increasing number of studies report the involvement of cryptic species in shaping these intricate fig-wasp communities in monoecious figs (Cook and Bean 2006; Darwell and Cook 2017), the necessity for comprehensive taxonomic studies employing phylogenetic analyses and species delineation becomes evident, with the specific aim of elucidating the functioning of this intricate ecosystem.

In recent decades, researches on Sycoscapter wasps have predominantly focused on ecological and evolutionary aspects (McLeish et al. 2010 2012; Sutton et al. 2016), with taxonomic studies remaining relatively scarce (Bouček 1988; Berg and Wiebes 1992; Pramanik and Dey 2019). In Taiwan, fig trees play an important ecological role in lowland vegetation, with some monoecious species being representative plants in urban environments (Chao et al. 2008; Walther et al. 2018). However, similar to the limited taxonomic research on symbiotic Sycoscapter wasps globally, only a few species have been documented in Taiwan, as noted by Chen et al. (1999). Therefore, using both morphological and phylogenetic approaches, the present study comprises a comprehensive taxonomic investigation of Sycoscapter wasps associated with Taiwanese monoecious fig species. The study aims to provide insight into the delimitation of cryptic species and enhance our understanding of the symbiotic relationship between figs and Sycoscapter wasps.

MATERIALS AND METHODS

Among the 28 Taiwanese Ficus taxa, 6 are monoecious species. These include Ficus nervosa Heyne ex Roth, Ficus pubinervis Bl., Ficus benjamina L. var. bracteata Corner, Ficus caulocarpa (Miq.) Miq., Ficus microcarpa L. f., and Ficus subpisocarpa Gagnep. Notably, the former two species belong to the subgenus Pharmacosycea, whereas the remaining four belong to the subgenus Spherosuke (Berg 2005 and Corner; Gardner et al. 2023). With the exception of F. pubinervis, which approaches its northern distribution boundary on Lanyu and Ludao islands, the other monoecious fig species exhibit broad distribution encompassing not only the whole of Taiwan but also extending to regions in South China and the Ryukyu islands of Japan (Table S1).

Given their wide distribution, D-phase figs (those ready for wasp release) were collected from various locations in Taiwan. Additionally, samples of F. microcarpa from adjacent regions were included in this study. Upon collection, figs were placed in containers with fine mesh until wasps emerged. Subsequently, all wasps were preliminarily identified and preserved in 95% alcohol. In addition, related specimens were also examined from museums and institutes, including the following: Department of Entomology at National Chung Hsing University, Taichung, Taiwan (NCHU); Taiwan Agricultural Research Institute, Taichung, Taiwan (TARI); Institute for Agro-Environmental Sciences, Ibaraki, Japan (NARO); and the Chinese Academy of Sciences, China (CAS).

For each population, one to five adult wasps were randomly selected, and genomic DNA was extracted from the whole body using the QuickExtract DNA Extraction Kit (Epicentre Biotechnologies, Madison, WI). Tissue was ground in 50 μL of QuickExtract solution and incubated at 65°C for 15 min, followed by 98°C for 2 min. A mitochondrial DNA gene, COI, and a nuclear ribosomal DNA gene, 28S, were used for molecular analyses of Sycoscapter wasps. Besides, combined COI+28S molecular data are recognized as valuable and commonly used in fig-wasp studies (Lopez-Vaamonde et al. 2009; Azuma et al. 2010; Yang et al. 2014). Primer sets LCO1490/HCO2198 for COI and D2-3551F/D2—4068R for 28S were used to amplify the two respective genes. Polymerase chain reaction conditions for the primer sets followed those described by Cruaud et al. (2010) and Heraty et al. (2004). After amplification, products were sequenced from both ends using a Taq Dye Terminator Cycle Sequencing Kit and an ABI 377A sequencer. All sequences have been deposited in GenBank under the following accession numbers: PP111396—PP111462 for COI sequences and PP162908—PP162951 for 28S sequences. Additionally, COI sequences of related wasp species from GenBank were incorporated into this study, including three populations of Sycoscapter associated with F. benjamina L., F. microcarpa L. f. and F. nervosa B. Heyne ex Roth.

Sequence alignment of COI was performed using the ClustalW algorithm in MEGA 11 (Tamura et al. 2021), and that of 28S was conducted on TurboFold Ⅱ web server (https://rna.urmc.rochester.edu/ RNAstructureWeb/Servers/TurboFold.html; Tan et al. 2017). Two fig wasp species, Walkerella kurandensis ex F. microcarpa (Pteromalidae: Otitesellini:

Otitesellina) and Sycoryctes patellais ex Ficus variegata (Pteromalidae: Otitesellini: Sycoryctina), belonging to the same tribe as Sycoscapter (http://www.figweb.org; van Noort and Rasplus 2024) were chosen as outgroup species. Owing to the unavailability of 28S sequences for the related species in GenBank, we constructed 28S tree and COI+28S tree based on the sequences generated in this study. Nucleotide substitution models GTR+I+G and GTR+I were determined as the bestfitting models for the COI gene and the 28S gene, respectively, using PartitionFinder 2 (Lanfear et al. 2012). Phylogenetic analyses were conducted using the maximum likelihood (ML) method on the IQ-TREE web server (http://iqtree.cibiv.univie.ac.at/) employing 1,000 ultrafast bootstrap replications (Nguyen et al. 2015; Trifinopoulos et al. 2016; Hoang et al. 2018). Bayesian inference (BI) analyses were conducted using MrBayes 3.2.7 (Ronquist et al. 2012), running Markov chain Monte Carlo methods for fifty million generations with sampling every 100 generations. Convergence was determined using Tracer 1.7.2 (Rambaut et al. 2018) with a threshold of all ESS parameters >200, and the initial 10% of trees were discarded as the burn-in. To determine the species delimitation of these Sycoscapter wasps in Taiwan, pairwise nucleotide divergence with Kimura 2-parameter (K2P) distance of COI gene and PTP model were conducted with MEGA 11 (Tamura et al. 2021) and bPTP web server (https://species.h-its. org/) employing 100,000 MCMC generations (Zhang et al. 2013), respectively.

Morphological measurements were performed using specimen and scanning electron microscopy (SEM) images captured with Keyence VHX and Hitachi S3400N microscopes, respectively. To prepare specimens for imaging, wasps were subjected to 1 min of agitation in an ultrasonic cleaner to remove pollen. Subsequently, specimens were serially dehydrated using ethanol and hexamethyldisilazane (Heraty and Hawks 1998) or critical point drying methods (Quoram E3100). Following dehydration, wasps were dissected and mounted on cards for specimen imaging or dissected and coated with gold using a Quorum SC7620 for SEM imaging. ImageJ software was used to perform measurements. The morphological terminology used in this study followed Bouček and Rasplus (1991) and Berg and Wiebes (1992). To assess the morphological relationship between Sycoscapter wasps associated with Taiwanese monoecious figs and similar described species, we followed the key provided by Priyadasarnan (2000) and Pramanik and Dey (2019), subsequently creating comparison tables. Abbreviations used in the taxonomic description include the following: L: length; W: width; H: height; POL: postocellar distance; and OOL: ocellocular distance.

RESULTS

Among the six monoecious fig tree species in Taiwan, F. pubinervis was notable for its absence of Sycoscapter wasps. Conversely, all other species exhibited a high prevalence and abundance of Sycoscapter wasps within their figs. In total, 81 COI sequences, including 14 from GenBank, with a length of 703 bp were aligned. Additionally, 46 specimens with 28S combined data, ranging from 630 to 631 bp in length, were included in the analysis. The COI phylogenetic tree revealed the presence of five clades, with each being supported by high values of both ML ultrafast bootstrap and BI posterior probability (Fig. 1). Contrastingly, the 28S phylogenetic tree showed only four clades, with wasps reared from figs of F. subpisocarpa and F. caulocarpa being combined into one clade (Fig. S1). Most clades in the COI tree exhibited a strong association with specific fig species, except for two cases involving F. microcarpa and F. benjamina, which shared Sycoscapter wasp species. This observation was also reflected in the COI+28S combined data, where five clades corresponding to Sycoscapter wasps associated with Taiwanese monoecious figs could be discerned (Fig. 2).

Despite the distinct and well-supported separation of the Sycoscapter species in Taiwanese monoecious figs, incongruence in tree topology was observed between the tree constructed using the COI gene and that constructed using COI+28S data. For example, in the COI tree, Clade Ⅱ appeared as a sister lineage to the group consisting of Clade Ⅲ-Ⅴ, then diverged from Clade I. In contrast, the tree based on COI+28S combined data grouped Clade Ⅱ with Clade Ⅲ. This incongruence was further supported by the relatively low values of both ML ultrafast bootstrap and BI posterior probability (Figs. 1 and 2).

Fig. 1.

Phylogenetic tree of the Sycoscapter species associated with monoecious figs in Taiwan and other congeners based on COI genes. The values at the nodes are the ultrafast bootstraps and posterior possibilities for maximum likelihood (ML) and Bayesian inference (BI) analyses, respectively. The number of each clade indicates the support value of the bPTP model.

Fig. 2.

Phylogenetic tree of the Sycoscapter species associated with monoecious figs in Taiwan based on COI+28S combined data. The values at the nodes are the ultrafast bootstraps and posterior possibilities for maximum likelihood (ML) and Bayesian inference (BI) analyses, respectively.

In addition to the genetic distances of 6.69–9.95% among species and 0.57–0.72% within species (Table 1), support values of the bPTP model (0.693–0.902) further supported the notion that the Sycoscapter wasps in this study represent five distinct species (Fig.1). Therefore, based on genetic differentiation and the topology of the phylogenetic tree reconstructed using COI+28S combined data, it is evident that five Sycoscapter species, corresponding to five clades, associated with monoecious figs exist in Taiwan, namely Sycoscapter gajimaru (Ishii), Sycoscapter piceoscapus Chou et Tzeng sp. nov., Sycoscapter monticola Chou et Tzeng sp. nov., Sycoscapter ishiianus Chou et Tzeng sp. nov., and Sycoscapter littoralis Chou et Tzeng sp. nov.

Table 1.

Percentage of pairwise nucleotide divergences with Kimura 2-parameter (K2P) distances and number of base pair differences based on the COI gene within and between species of Sycoscapter wasps associated with monoecious figs in Taiwan. In the inter-species column, the lower-left values are K2P distances and upper-right are bp differences

In terms of morphological observation, each species could be readily identified as a member of Sycoscapter by specific characteristics, such as symmetric funicles and a “boot-like” stigma on the forewing in females, and two terga in dorsal view and a non-enlarged basitarsus on the hind legs in males. Comparative analyses with other related Sycoscapter species revealed that Taiwanese species could be categorized into four morpho-groups based on similarities in male head-shape morphology. Sycoscapter gajimaru, for instance, clustered with Sycoscapter stabilis (Walker) and Sycoscapter benghalensis Pramanik and Dey owing to similarities in male head shape (rectangular with curved lateral margins). However, these species still differed based on other characters, such as vertex shape, setae number on female forewings, and malar L/eye L ratio in males (Table 2). As shown in table 3, S. piceoscapus and S. benghalensis Pramanik and Dey formed a morphogroup owing to shared characteristics, such as ovate head shape and large compound eyes in males, although they could be differentiated based on female characters, including vertex shape and scape coloration. Sycoscapter monticola exhibited a unique subhexagonal head shape in males, setting it apart from Sycoscapter vijayaii Priyadarsanan, although both share the same host fig species. Moreover, there were distinguishing features in male antennal segments (Table 4). The last group encompassed three species, namely S. ishiianus, S. infectorius (Joseph), and S. littoralis, which exhibited a long rectangular head shape with straight lateral margins. However, they could be distinguished through various characters, including head shape, maxillary palp segment in females, and the spur on the fore tibia in males (Table 5).

Table 2.

Comparison of morphological characters between Sycoscapter gajimru (Ishii), S. stabilis (Walker) and S. benghalensis Pramanik and Dey

Table 3.

Comparison of morphological characters between Sycoscapter picescapus sp. nov. and S. benjaminae Pramanik and Dey

Table 4.

Comparison of morphological characters between Sycoscapter monticola sp. nov. and S. vijayaii Priyadarsanan

Table 5.

Comparison of morphological characters between Sycoscapter ishiianus sp. nov., S. infectorius (Joseph) and S. littoralis sp. nov.

In addition to head shape in males, the presence or absence of rudimentary wing vestiges in males could also be used to categorize Sycoscapter wasps into two morpho-groups. Notably, wasps possessing rudimentary wing vestiges were exclusively associated with monoecious figs, whereas those lacking vestiges were associated with functional dioecious figs.

TAXONOMY

Family Pteromalidae Dalman, 1820

Genus Sycoscapter Saunders, 1883

Sycoscapter gajimaru (Ishii, 1934)

(Figs. 3, 4, 5)

Goniogaster gajimaru Ishii, 1934: 89, pls. 2(20).

Sycoscapter gajimaru Wiebes, 1964: 83 (Japan); Yokoyama and Iwatsuki, 1998: 43 (Japan); Chen et al. 1999: 73, fig. 19 (Taiwan); Karube et al. 2022: 51, fig. 43 (Kita-Iwo, Japan; introduced).

Type locality: Naha, Okinawa, Japan.

Material examined: Lectotype: 1♀, Naha, Okinawa, 22-Ⅲ-1934, Col. T. Ishii (NARO), designated here. Others: Japan: 1♀1♂, Naha (26.226520, 127.713802), Okinawa, ex Ficus microcarpa L. f., 3-VI-2023, leg. P. A. Chou (NCHU); 1♀, Amami (28.391214, 129.506937), Kagoshima, ex Ficus microcarpa L. f., 9-V-2021, leg. K. Arimoto (NCHU); 1♀, Minamidaito (25.836189, 131.237121), Okinawa, ex Ficus microcarpa L. f., 20-V-2022, leg. K. Arimoto (NCHU). Taiwan: 1♂1♀, Fugui Cape (25.292583, 121.538262), New Taipei City, ex Ficus microcarpa L.

f., 13-IX-2020, leg. P. A. Chou (NCHU); 1♀, National Taiwan University, Taipei City, ex Ficus microcarpa L. f., 6-IX-1991, leg. C. F. Hsu (TARI); 1♀, Taichung Park, Taichung City, ex Ficus microcarpa L. f., 15-IX1991, leg. K. S. Lin (TARI); 1♀, Wanfeng, Taichung City, ex Ficus microcarpa L. f., 8-X-1991, leg. K. S. Lin (TARI); 1♂1♀, Botanical Garden of National Museum of Natural Science (24.158742, 120.667746), Taichung City, ex Ficus benjamina L. var. bracteata Corner, 27IV-2023, leg. P. A. Chou (NCHU); 1♀, Yuanlin Park, Changhua, ex Ficus microcarpa L. f., 13-IX-1991, leg. K. S. Lin (TARI); 1♀, Tsaotun, Nantou, ex Ficus microcarpa L. f., 8-X-1991, leg. K. S. Lin (TARI); 1♀, Kenting Forest Recreation Area (21.961888, 120.814306), Pingtung, ex Ficus microcarpa L. f., 11Ⅷ-2022, leg. P. A. Chou (NCHU); 1♂1♀, Kenting Forest Recreation Area (21.964254, 120810716), Pingtung, ex Ficus benjamina L. var. bracteata Corner, 11-VIII-2022, leg. P. A. Chou (NCHU); 1♀, Tali, Ilan, ex Ficus microcarpa L. f., 14-IX-1991, leg. T. F. Hsu (TARI); 1♂1♀, Shitiping (23.491086, 121.508953), Hualien, ex Ficus microcarpa L. f., 29-VIII-2018, leg. P. A. Chou (NCHU); 1♂1♀, Taitung Seashore Park (22.751414, 121.610591), Taitung, ex Ficus microcarpa L. f., 25-Ⅲ-2023, leg. P. A. Chou (NCHU); 1♂1♀, Ludao (22.671815, 121.505912), Taitung, ex Ficus microcarpa L. f., 30-VIII-2018, leg. P. A. Chou (NCHU).

Description: Female: Whole L = 3.82–4.93 mm with body L = 1.08–1.43 mm and ovipositor sheath L = 2.74–3.50 mm. Body metallic green (Fig. 3C). Compound eyes pale red (Fig. 3A). Antenna scape and pedicel yellow, anelli, funicle and clava black (Fig. 3I). Legs yellow (Fig. 3J, 3L, 3N) except for the basal part of hind coxa black in antiaxial view (Fig. 3N).

Fig. 3.

Sycoscapter gajimaru (Ishii, 1934). A, Female head, front; B, Female mesosoma, dorsal; C, Female habitus, lateral; D, Male habitus, lateral; E, Male head, dorsal; F, Male mesosoma, dorsal; G, Female left mandible, ventral; H, Male left mandible, dorsal; I, Female antenna; J, Female right foreleg; K, Male right foreleg; L, Female right mid leg; M, Male right mid leg; N, Female right hind leg; O, Male right hind leg; P, Female forewing. Scale bar = 0.1 mm if no number is noted.

Head: Obcordate in front view (Fig. 3A); H = 0.26 mm, W over compound eyes = 0.32 mm, W between compound eyes = 0.22 mm. Compound eye H 1.5× malar space L, and 3× compound eyes W. POL 7.49× OOL. Clypeus margin with a thin projection in the middle (Fig. 4A). Face and antennal scrobes with raised reticulation (Fig. 3A). Mandible bidentate (Fig. 3G). Maxillary palp 3-segmented; length ratio = 3:4:4 (Fig. 4B). Labial palp 2-segmented; length ratio = 3:2 (Fig. 4B). The distance between toruli 0.3× clypeus margin. Antennal formula 11253 and L = 0.49 mm; length ratio of scape, pedicel, anelli, funicle and clava = 14:4:1:20:10 (Fig. 3I). Scape L 3.85× W, with sparse trichoid sensillae (Fig. 4C). Pedicel L 1.3× W, with sparse trichoid sensillae (Fig. 4C). Both anelli equal in length and the second one wider (Fig. 4C). All funicular segments equal in length; the first funicular segment L 0.92× W, with 3 multiporous placoid sensillae and 8 chaetica sensillae in antiaxial view; the chaetica sensilla longer than funicular segment (Fig. 4C). Claval segments slightly wider than funicular segments; the first claval segment L 0.76× W, with 3 multiporous placoid sensillae and 7 chaetica sensillae in antiaxial view.

Fig. 4.

Scanning electron images of female Sycoscapter gajimaru (Ishii, 1934). A, Toruli and epistomal margin; B, Maxillary palps and labial palps; C, Anelli and the first funiculus; D, Scutellum; E, Left fore tibia, axial; F, Right tibia, antiaxial; G, Left mid tibia, axial; H, Right mid tibia, antiaxial; I, Right hind tibia, axial; J, Left hind tibia, antiaxial. Scale bar = 0.03 mm.

Mesosoma: Mesosoma L = 0.41 mm, W = 0.29 mm; length ratio of pronotum, scutum, scutellum and propodeum = 2:4:5:1. Pronotum, scutum and scutellum with raised reticulation but propodeum psilate (Fig. 3B) Pronotum with collar in ventral view. Scutum with incomplete notauli (Fig. 3B). Scutellum nearly as wide as long; punctures of reticulation rounded (Fig. 4D). Metanotum strongly compressed and the middle covered by scutellum. Propodeum transverse with two longitudinal keels. Forewing L = 1.01 mm, W = 0.44 mm, with 5–7 setae below the marginal vein; length ratio of submarginal vein, marginal vein, postmarginal vein and stigmal vein = 5:3:4:2 (Fig. 3P). Hind wing L = 0.58 mm, W = 0.12 mm; length ratio of submarginal vein and marginal vein = 2:3. Foreleg L = 0.65 mm; length ratio of coxa, trochanter, femur, tibia and tarsus = 3:2:5:4:3 (Fig. 3J). Fore tibia with a curve, bidentate spur reaching the apex of first tarsomere; 1 spine beside spur in both axial and antiaxial views (Fig. 4E, 4F). Fore tarsus 5-segmented; length ratio of each segment = 4:3:3:2:7. Mid leg L = 0.67 mm; length ratio of coxa, trochanter, femur, tibia and tarsus = 1:1:3:4:3 (Fig. 3L). Mid tibia with a straight spur; spur L 0.5× the first tarsomere L; 1 spine beside spur in axial view but no spine in antiaxial view (Fig. 4G, 4H). Mid tarsus 5-segmented; length ratio of each segment = 7:4:3:2:4. Hind leg L = 0.92 mm; length ratio of coxa, trochanter, femur, tibia and tarsus = 3:1:4:5:3 (Fig. 3N). Hind tibia with a straight spur; spur L 0.5× the first tarsomere L; 19-24 teeth in axial view and 3 spines beside spur in antiaxial view (Fig. 4I, 4J). Hind tarsus 5-segmented; length ratio of each segment = 8:4:3:2:5.

Metasoma: Abdomen without ovipositor sheath L = 0.74 mm.

Male: L = 1.33–1.40 mm. Body brown (Fig. 3D). Eyes black (Fig. 3E). Mandible dark brown (Fig. 3H). Antenna pale yellow (Fig. 3E). Legs brown (Fig. 3K, 3M, 3O).

Head: Rectangular shape in dorsal view (Fig. 3E); L without mandible = 0.45 mm, W = 0.38 mm. Mandible L = 0.25 mm, W = 0.10 mm. Mandible falcate with a fine tooth in the middle (Fig 3H). Clypeus margin concave in the middle. Maxillary palp 4-segmented; length ratio = 3:3:1:3 (Fig. 5B). Labial palp 2-segmented; length ratio = 3:2 (Fig. 5B). Compound eye L 2.5× W. Malar space L 1.79× compound eye L. Toruli close to clypeus margin. Antennal formula 11153 and L = 0.37 mm; length ratio of scape, pedicel, anellus, funicle and clava = 11:7:1:8:7. Scape L 2.51× W, with sparse trichoid sensillae (Fig. 5A). Pedicel L 3.32× W, with sparse trichoid sensillae (Fig. 5A). The first and third funicular segment swollen, L 0.6× W; other funicular segments L 0.55× W; all funicular segments with trichoid sensillae (Fig. 5A). Claval segments as wide as the swollen funicular segments; the first claval segment L 0.9× W, with trichoid sensillae and multiporus placoid sensillae (Fig. 5A).

Fig. 5.

Scanning electron images of male Sycoscapter gakimaru (Ishii, 1934). A, Antenna; B, Maxillary palps and labial palps; C, Left fore tibia, axial; D, Right tibia, antiaxial; E, Left mid tibia, axial; F, Right mid tibia, antiaxial; G, Right hind tibia, axial; H, Left hind tibia, antiaxial. Scale bar = 0.03 mm.

Mesosoma: Long pentagon in dorsal view (Fig. 3F); L = 0.54 mm, W = 0.39 mm; length ratio of pronotum and the fused tergum = 4:3. Pronotum with collar in ventral view. Mesonotum, metanotum and propodeum fused in dorsal view (Fig. 3F). Rudimentary wing vestige present, L = 0.39 mm (Fig. 3F). Foreleg L = 0.85 mm; length ratio of coxa, trochanter, femur, tibia and tarsus = 4:1:3:3:2 (Fig. 3K). Fore tibia with a slightly curve, bidentate spur reaching the last tarsomere; 11–12 spines in axial view and 15–16 spines in antiaxial view (Fig. 5C, 5D). Fore tarsus 5-segmented; length ratio of each segment = 2:1:1:1:10. Mid leg L = 0.67 mm; length ratio of coxa, trochanter, femur, tibia and tarsus = 2:1:2:2:2 (Fig. 3M). Mid tibia with a straight spur reaching the fourth tarsomere; 13 spines in axial view and 12–13 spines in antiaxial view (Fig. 5E, 5F). Mid tarsus 5-segmented; length ratio of each segment = 2:1:1:1:6. Hind leg L = 0.92 mm; length ratio of coxa, trochanter, femur, tibia and tarsus = 7:2:5:6:4 (Fig. 3O). Hind tibia with a straight spur reaching the fourth tarsomere; 15–18 spines in axial view and 23 spines in antiaxial view (Fig. 5G, 5H). Hind tarsus 5-segmented; length ratio of each segment = 1:1:1:1:4.

Metasoma: Abdomen L = 0.53 mm.

Host: Ficus microcarpa L. f. and Ficus benjamina L. var. bracteata Corner.

Distubution: Taiwan; Japan: Ryukyu islands and Kita-Iwo (introduced).

Diagnosis: This species is similar to S. benghalansis Pramanik and Dey but can be distinguished by the characters, following the key provided by Pramanik and Dey (2019), in female including the seta number on forewing (5–7 in S. gajimaru vs. 23 in S. benghalensis), the ratio of ovipositor L to metasoma L (4.03 in S. gajimaru vs. 4.7 in S. benghalensis); in male including the ratio of malar space L to eye L (1.79 in S. gajimaru vs. 1 in S. benghalensis). This species is also similar to S. stabilis (Walker) but can be distinguished by the characters in female including the ratio of ovipositor to metasoma (4.03 in S. gajimaru vs. 5.3 in S. stabilis) and vertex shape (concave in S. gajimaru vs. straight in S. stabilis); in male including the ratio of mandible L to W (2.3 in S. gajimaru vs. 1.7 in S. stabilis). Despite the differences above, ambiguous delimitation between males of S. gajimaru and S. stabilis still exists, with males of the latter species reported to have variable characters (Wiebes 1967).

Remarks: Ishii (1934) published two Sycoscapter species, S. inubiae (= Goniogaster inubiae) and S. gajimaru (= G. gajimaru). In that description, the projection on clypeus margin of the former was sharp while that of the latter was thin. However, the figures showed the projection of S. inubiae [Ishii (1934): Fig. 12] was thinner than that of S. gajimau [Ishii (1934):

Fig. 20]. After examining samples of S. gajimaru and S. inubiae, we think figures of the two species were numbered mistakenly.

Ishii (1934) did not designate the holotype of Sycoscapter gajimaru (= Goniogaster gajimaru), but only one specimen with the same collection information was found in NARO. Therefore, this specimen should be designated as the lectotype. Since this species could be distinguished from others by the characters of the mesosoma, this lectotype could present its diagnostic characters even if in the headless condition (Fig. S2).

Sycoscapter piceoscapus Chou & Tzeng sp. nov.

(Figs. 6, 7, 8)

urn:lsid:zoobank.org:act:BF014E39-A51E-43EC-B264-

B4AB83AFCAB5

Type locality: National Chung-Hsing University, Taichung, Taiwan.

Material examined: Holotype: 1♀, National Chung-Hsing University (24.122583, 120.677985), Taichung, ex Ficus microcarpa L. f., 17-Ⅱ-2020, leg. P. A. Chou (NCHU). Paratypes: 1♂, National Chung-Hsing University (24.122583, 120.677985),

Taichung, ex Ficus microcarpa L. f., 17-Ⅱ-2020, leg. P. A. Chou (NCHU); 1♂1♀, Botanical Garden of National Museum of Natural Science (24.158790, 120.667772), Taichung City, ex Ficus microcarpa L. f., 7-VII-2018, leg. P. A. Chou (TARI). Others: Taiwan: 1♀, National Chiao Tung University (24.789220, 121.000047), Hsinchu, ex Ficus microcarpa L. f., 20Ⅹ-2022, leg. C. Y. Huang (NCHU); 1♂1♀, National Chung-Hsing University (24.122583, 120.677985),

Taichung, ex Ficus microcarpa L. f., 8-Ⅲ-2019, leg. P. A. Chou (NCHU); 1♂1♀, Taipin (24.116256, 120.732507), Taichung City, ex Ficus microcarpa L. f., 7-IV-2023, leg. C. Y. Huang (NCHU); 1♂1♀, Changhua City (24.083587, 120.556162), Chunghua, ex Ficus microcarpa L. f., 9-VIII-2022, leg. C. Y. Huang (NCHU); 1♂1♀, Botanical Garden of National Museum of Natural Science (24.158742, 120.667746), Taichung City, ex Ficus benjamina L. var. bracteata Corner, 27-IV-2023, leg. P. A. Chou (NCHU); 1♂1♀, Mt. Wuhu (24.501129, 118.437810), Kinmen, ex Ficus microcarpa L. f., 4-VIII-2021, leg. P. A. Chou (NCHU). China: 1♂1♀, South China National Botanical Garden (23.183609, 113.370332), Guangdong Prov. ex Ficus microcarpa L. f., 16-ⅩⅡ-2018, leg. P. A. Chou (NCHU). 8♂4♀, Danzhou (19.52, 109.57), Hainan Prov. ex Ficus microcarpa L. f., 24-IV-2004, col. G. Feng, W. Li, H. Y. Hu, L. M. Niu (CAS) (examined from online photographs); 10♂10♀, Zhuang (19.747, 109.411), Hainan Prov., ex Ficus benjamina L., 24-IV-2004, col. G. Feng, W. Li, H. Y. Hu, L. M. Niu (CAS) (examined from online photographs).

Description: Female: Whole L = 3.65–4.08 mm with body L = 0.95–1.08 mm and ovipositor sheath L = 2.69–3.0 mm. Body metallic green (Fig. 6C). Compound eyes pale red (Fig. 6A). Antenna black with yellow coloration on the basal part of the scape (Fig. 6I). Legs yellow (Fig. 6J, 6L, 6N); middle of mid femur slightly black in antiaxial view (Fig. 6L); basal part of hind coxa black in antiaxial view (Fig. 6N).

Fig. 6.

Sycoscapter piceoscapus sp. nov. A, Female head, front; B, Female mesosoma, dorsal; C, Female habitus, lateral; D, Male habitus, lateral; E, Male head, dorsal; F, Male mesosoma, dorsal; G, Female left mandible, ventral; H, Male left mandible, dorsal; I, Female antenna; J, Female right foreleg; K, Male right foreleg; L, Female right mid leg; M, Male right mid leg; N, Female right hind leg; O, Male right hind leg; P, Female forewing. Scale bar = 0.1 mm if no number is noted.

Head: Obcordate in front view (Fig. 6A); H = 0.25 mm, W over compound eyes = 0.34 mm, W between compound eyes = 0.23 mm. Compound eye H = 1.28× malar space, and 2.59× compound eye W. POL 7.07× OOL. Clypeus margin with a thin and blunt projection in the middle (Fig. 7A). Face and antennal scrobes with raised reticulation (Fig. 6A). Mandible bidentate (Fig. 6G). Maxillary palp 3-segmented, length ratio = 2:3:5 (Fig. 7B). Labial palp 2-segmented, length ratio = 3:2 (Fig. 7B). The distance between toruli 0.33× clypeus margin. Antennal formula 11253 and L = 0.51 mm; length ratio of scape, pedicel, anelli, funicle and clava = 14:4:1:20:10 (Fig. 6I). Scape L 5.34× W, with sparse trichoid sensillae (Fig. 7C). Pedicel L 1.18× W, with sparse trichoid sensillae (Fig. 7C). Both anelli equal in length and the second one wider (Fig. 7C). All funicular segments equal in length; the first funicular segment L 0.81× W, with 2 multiporous placoid sensillae and 6 chaetica sensillae in antiaxial view; the chaetica sensilla longer than funicular segment (Fig. 7C). Claval segments slightly wider than funicular segments. The first claval segments L 0.81× W, with 3 multiporous placoid sensillae and 6 chaetica sensillae in antiaxial view.

Fig. 7.

Scanning electron images of female Sycoscapter piceoscapus sp. nov. A, Toruli and epistomal margin; B, Maxillary palps and labial palps; C, Anelli and the first funiculus; D, Scutellum; E, Left fore tibia, axial; F, Right tibia, antiaxial; G, Left mid tibia, axial; H, Right mid tibia, antiaxial; I, Right hind tibia, axial; J, Left hind tibia, antiaxial. Scale bar = 0.03 mm.

Mesosoma: Mesosoma L = 0.36 mm, W = 0.26 mm; length ratio of pronotum, scutum, scutellum and propodeum = 2:5:8:2. Pronotum, scutum and scutellum with raised reticulation but propodeum psilate in dorsal view (Fig. 6B) Pronotum with collar in ventral view. Scutum with incomplete notauli (Fig. 6B). Scutellum nearly as wide as long, punctures of reticulation lengthened longitudinally (Fig. 7D). Metanotum strongly compressed and the middle covered by scutellum. Propodeum transverse, with two longitudinal keels. Forewing L = 1.09 mm, W = 0.46 mm, with 7–10 setae below the marginal vein; length ratio of submarginal vein, marginal vein, postmarginal vein and stigmal vein = 5:3:4:2 (Fig. 6P). Hind wing L = 0.75 mm, W = 0.18 mm; length ratio of submarginal vein and marginal vein =2:3. Foreleg L = 0.61 mm; length ratio of coxa, trochanter, femur, tibia and tarsus = 3:2:5:4:3 (Fig. 6J). Fore tibia with a curve, bidentate spur reaching the apex of first tarsomere; 2 spines beside spur in axial view and 2 spines in antiaxial view (Fig. 7E, 7F). Fore tarsus 5-segmented; length ratio of each segment = 4:3:3:2:7. Mid leg L = 0.63 mm; length ratio of coxa, trochanter, femur, tibia and tarsus = 1:1:3:4:3 (Fig. 6L). Mid tibia with a straight spur; spur L 0.5× the first tarsomere L; 1 spine beside spur in axial view but no spine in antiaxial view (Fig. 7G, 7H). Mid tarsus 5-segmented; length ratio of each segment = 7:4:3:2:4. Hind leg L = 0.84 mm; length ratio of coxa, trochanter, femur, tibia and tarsus = 3:1:4:5:3 (Fig. 6N). Hind tibia with a straight spur; spur L 0.5× the first tarsomere L; 21-23 teeth in axial view and 2 spines beside spur in antiaxial view (Fig. 7I, 7J). Hind tarsus 5-segmented; length ratio of each segment = 8:4:3:2:5.

Metasoma: Abdomen without ovipositor sheath L = 0.57 mm.

Male: L = 1.22–1.30 mm. Body brown (Fig. 6D). Eyes black (Fig. 6E). Mandible dark brown (Fig. 6H). Antenna pale yellow (Fig. 6E). Legs brown (Fig. 6K, 6M, 6O).

Head: Long ovate in dorsal view (Fig. 6E); L without mandible = 0.40 mm, W = 0.35 mm. Mandible L = 0.22 mm, W = 0.1 mm. Mandible falcate with a fine tooth at the middle (Fig 6H). Clypeus margin concave in the middle. Maxillary palp 4-segmented, length ratio = 3:3:1:2 (Fig. 8B). Labial palp 2-segmented, length ratio = 3:2 (Fig. 8B). Compound Eye L 3.5× W. Malar space L 1.03× compound eye L. Toruli close to clypeus margin. Antennal formula 11153 and L = 0.34 mm; length ratio of scape, pedicel, anellus, funicle and clava = 13:7:1:8:7. Scape L 3.35× W, with sparse trichoid sensillae (Fig. 8A). Pedicel L 2.78× W, with sparse trichoid sensillae (Fig. 8A). The first and third funicular segments swollen, L 0.55× W; other funicular segments L 0.47× W. All funicular segments with trichoid sensillae (Fig. 8A). Claval segments as wide as the swollen funicular segments, the first segment L 0.88× W, with trichoid sensillae and multiporus placoid sensillae (Fig. 8A).

Mesosoma: Oblong in dorsal view (Fig. 6F). L = 0.46 mm, W = 0.34 mm; length ratio of pronotum and the fused tergum = 3:2. Pronotum with collar in ventral view. Mesonotum, metanotum and propodeum fused in dorsal view (Fig. 6F). Rudimentary wing vestige present, L = 0.33 mm (Fig. 6F). Foreleg L = 0.81 mm; length ratio of coxa, trochanter, femur, tibia and tarsus = 4:1:3:3:2 (Fig. 6K). Fore tibia with a slightly curve, bidentate spur reaching the last tarsomere; 5–6 spines in axial view and 10–14 spines in antiaxial view (Fig. 8C, 8D). Fore tarsus 5-segmented; length ratio of each segment = 2:1:1:1:6. Mid leg L = 0.69 mm; length ratio of coxa, trochanter, femur, tibia and tarsus L = 2:1:2:2:2 (Fig. 6M). Mid tibia with a straight spur reaching the second tarsomere; 8 spines in axial view and 13–14 spines in antiaxial view (Fig. 8E, 8F). Mid tarsus 5-segmented; length ratio of each segment = 1:1:1:1:5. Hind leg L = 0.96 mm; length ratio of coxa, trochanter, femur, tibia and tarsus = 4:1:3:3:2 (Fig. 6O). Hind tibia with a straight spur reaching the third tarsomere; 15–17 spines in axial view and 23–25 spines in antiaxial view (Fig. 8G, 8H). Hind tarsus 5-segmented, length ratio of each segment = 1:1:1:1:4.

Fig. 8.

Scanning electron images of male Sycoscapter piceoscapus sp. nov. A, Antenna; B, Maxillary palps and labial palps; C, Left fore tibia, axial; D, Right tibia, antiaxial; E, Left mid tibia, axial; F, Right mid tibia, antiaxial; G, Right hind tibia, axial; H, Left hind tibia, antiaxial. Scale bar = 0.03 mm.

Metasoma: Abdomen L = 0.44 mm.

Host: Ficus microcarpa L. f. and Ficus benjamina L.

Distubution: Taiwan: Hsinchu, Taichung, Changhua, Kinmen; China: Guangdong, Hainan.

Etymology: This species is named after the dark coloration of the scape in females.

Diagnosis: This species is similar to S. benjaminae Pramanik and Dey but can be distinguished by the characters in female including vertex shape (concave in S. piceoscapus vs. straight in S. benjaminae), scape coloration (black in S. piceoscapus vs. yellow in S. benjaminae), sculpture on antennal scrobe (reticulate in S. piceoscapus vs. psilate in S. benjaminae); in male including the ratio of rudimentary wing vestige L to mesosoma L (1.39 in S. piceoscapus vs. 1.7 in S.

benjaminae).

Remarks: This species has the same hosts as S. gajimaru, and may co-occur in the same tree with S.

gajimaru.

Sycoscapter monticola Chou & Tzeng sp. nov.

(Figs. 9, 10, 11)

urn:lsid:zoobank.org:act:5FC6CCEC-2A06-458A-956BD4639EB3CB75

Type locality: Zhiben Forest Road, Taitung, Taiwan.

Material examined: Holotype: 1♀, Zhiben Forest Road (22.783507, 120.015736), Taitung, ex Ficus nervosa Heyne ex Roth., 10-V-2021, leg. P. A. Chou (NCHU). Paratypes: 1♂, Zhiben Forest Road (22.783507, 120.015736), Taitung, ex Ficus nervosa Heyne ex Roth., 10-V-2021, leg. P. A. Chou (NCHU); 1♂1♀, Qidu (25.122708, 121.662235), Keelung, ex Ficus nervosa Heyne ex Roth., 19-IX-2022, leg. P. A. Chou (TARI). Others: Taiwan: 1♂1♀, Urai (24.856259, 121.553437), New Taipei City, ex Ficus nervosa Heyne ex Roth., 11-ⅩⅡ-2019, leg. P. A. Chou (NCHU); 1♂1♀, Nan’ao (24.457640, 121.813020), Yilan, ex Ficus nervosa Heyne ex Roth., 26-Ⅲ-2023, leg. P. A. Chou (NCHU). China: 5♀, Bawangling (19.099, 109.176), Hainan Prov., ex Ficus nervosa Heyne ex Roth., 11-IV-2007, col. G. Feng, W. Li, H. Y. Hu, L. M. Niu (CAS) (examined from online photographs).

Description: Female: Whole L = 5.23–5.54 mm with body L = 1.40–1.42 mm and ovipositor sheath L = 3.83–4.12 mm. Body metallic green (Fig. 9C). Compound eyes pale red (Fig. 9A). Antenna black except for the basal part of scape yellow (Fig. 9I). Legs yellow (Fig. 9J, 9L, 9N) except for the basal part of hind coxa black in antiaxial view (Fig. 9N).

Fig. 9.

Sycoscapter monticola sp. nov. A, Female head, front; B, Female mesosoma, dorsal; C, Female habitus, lateral; D, Male habitus, lateral; E, Male head, dorsal; F, Male mesosoma, dorsal; G, Female left mandible, ventral; H, Male left mandible, dorsal; I, Female antenna; J, Female right foreleg; K, Male right foreleg; L, Female right mid leg; M, Male right mid leg; N, Female right hind leg; O, Male right hind leg; P, Female forewing. Scale bar = 0.1 mm if no number is noted.

Head: Obcordate in front view (Fig. 9A); H = 0.27 mm; W over compound eyes = 0.34 mm; W between compound eyes = 0.23 mm. Compound eye H 1.24× malar space L, and 2.98× compound eyes W. POL 4.84× OOL. Clypeus margin with a blunt projection in the middle (Fig. 10A). Face with raised reticulation but antennal scrobes psilate (Fig. 9A). Mandible bidentate (Fig. 9G). Maxillary palp 3-segmented, length ratio of others = 2:2:5 (Fig. 10B). Labial palp 2-segmented, length ratio = 3:2 (Fig. 10B). The distance between toruli 0.18× clypeus margin. Antennal formula 11253 and L = 0.50 mm; length ratio of scape, pedicel, anelli, funicle and clava = 14:4:1:20:10 (Fig. 9I). Scape L 4.43× W, with sparse trichoid sensillae (Fig. 10C). Pedicel L 1.55× W, with sparse trichoid sensillae (Fig. 10C). Both anelli equal in length and the second one wider (Fig. 10C). All funicular segments equal in length; the first funicular segment L 1.09× W, with 3 multiporous placoid sensillae and 5 chaetica sensillae in antiaxial view; the chaetica sensilla longer than the funicular segment (Fig. 10C). Claval segments W almost equal to funicular segments, the first claval segment L 0.87× W, with 3 multiporous placoid sensillae and 5 chaetica sensillae in antiaxial view.

Fig. 10.

Scanning electron images of female Sycoscapter monticola sp. nov. A, Toruli and epistomal margin; B, Maxillary palps and labial palps; C, Anelli and the first funiculus; D, Scutellum; E, Left fore tibia, axial; F, Right tibia, antiaxial; G, Left mid tibia, axial; H, Right mid tibia, antiaxial; I, Right hind tibia, axial; J, Left hind tibia, antiaxial. Scale bar = 0.03 mm.

Mesosoma: Mesosoma L = 0.47 mm, W = 0.31 mm; length ratio of pronotum, scutum, scutellum and propodeum = 2:3:4:1. Pronotum, scutum and scutellum with raised reticulation but propodeum psilate in dorsal view (Fig. 9B) Pronotum with collar in ventral view. Scutum with incomplete notauli (Fig. 9B). Scutellum nearly as wide as long, punctures of reticulation lengthened longitudinally (Fig. 10D). Metanotum strongly compressed and the middle covered by scutellum. Propodeum with two longitudinal keels. Forewing L = 1.09 mm, W = 0.51 mm, with 4-11 setae below the marginal vein; length ratio of submarginal vein, marginal vein, postmarginal vein and stigmal vein = 5:3:4:2 (Fig. 9P). Hind wing L = 0.70 mm, W = 0.18 mm; length ratio of submarginal vein and marginal vein = 2:3. Foreleg L = 0.76 mm; length ratio of coxa, trochanter, femur, tibia and tarsus = 3:2:5:4:3 (Fig. 9J). Fore tibia with a curve, bidentate spur reaching the apex of first tarsomere; 2-3 spines beside spur in axial view and 1 spine in antiaxial views (Fig. 10E, 10F). Fore tarsus 5-segmented, length ratio of each segment = 4:3:3:2:7. Mid leg L = 0.80 mm; length ratio of coxa, trochanter, femur, tibia and tarsus = 1:1:3:4:3 (Fig. 9L). Mid tibia with a straight spur; spur L 0.5× the first tarsomere L; 1 spine beside spur in axial view and 1 spine in antiaxial view (Fig. 10G, 10H). Mid tarsus 5-segmented, length ratio of each segment = 6:4:3:2:5. Hind leg L = 1.05 mm; length ratio of coxa, trochanter, femur, tibia and tarsus = 3:1:4:5:3 (Fig. 9N). Hind tibia with a straight spur; spur L 0.5× the first tarsomere L; 23-30 teeth in axial view and 2 spines beside spur in antiaxial view (Fig. 10I, 10J). Hind tarsus 5-segmented, length ratio of each segment = 9:4:3:2:5.

Metasoma: Abdomen without ovipositor sheath L = 0.63 mm.

Male: L = 1.57–1.70 mm. Body brown (Fig. 9D). Eyes black (Fig. 9E). Mandible dark brown (Fig. 9H). Antenna pale yellow (Fig. 9E). Legs brown (Fig. 9K, 9M, 9O).

Head: Subhexagonal in dorsal view (Fig. 9E). L without mandible = 0.50 mm; W = 0.60 mm. Mandible L = 0.31 mm, W = 0.15 mm. Mandible falcate with a fine tooth at the middle (Fig 9H). Clypeus margin concave in the middle. Maxillary palp 4-segmented, length ratio = 2:2:1:2 (Fig. 11B). Labial palp 2-segmented, length ratio= 3:1 (Fig 11B). Compound eye L 3× W. Malar space L 1.14× compound eye L. Toruli close to clypeus margin, with a ridge in the middle. Antennal formula 11153 and L = 0.39 mm; length ratio of scape, pedicel, anellus, funicle and clava = 11:7:1:8:7. Scape L 4.45× W, with sparse trichoid sensillae (Fig. 11A). Pedicel L 3.89× W, with sparse trichoid sensillae (Fig. 11A). The first and third funicular segments swollen, L 0.63× W; all funicular segments with trichoid sensillae (Fig. 11A). Claval segments as wide as the swollen segments; the first claval segment L 0.71× W, with trichoid sensillae and multiporus placoid sensillae (Fig. 11A).

Mesosoma: Oblong in dorsal view (Fig. 9F); L = 0.63 mm, W = 0.45 mm; length ratio of pronotum and the fused tergum = 3:2. Pronotum with collar in ventral view. Mesonotum, metanotum and propodeum fused in dorsal view (Fig. 9F). Rudimentary wing vestige present, L = 0.44 mm (Fig. 9F). Foreleg L = 0.92 mm; length ratio of coxa, trochanter, femur, tibia and tarsus = 3:1:2:2:2 (Fig. 9K). Fore tibia with a slightly curve, bidentate spur reaching the last tarsomere; 6 spines in axial view and 13–14 spines in antiaxial view (Fig. 11C, 11D). Fore tarsus 5-segmented, length ratio of each segment = 2:1:1:2:12. Mid leg L = 0.82 mm; length ratio of coxa, trochanter, femur, tibia and tarsus = 2:1:2:2:2 (Fig. 9M). Mid tibia with a straight spur reaching the second tarsomere; 14–15 spines in axial view and 13–16 spines in antiaxial view (Fig. 11E, 11F). Mid tarsus 5-segmented, length ratio of each segment = 2:1:1:1:6. Hind leg L = 1.17 mm; length ratio of coxa, trochanter, femur, tibia and tarsus = 7:2:5:6:4 (Fig. 9O). Hind tibia with a straight spur reaching the third tarsomere; 18–20 spines in axial view and 23 spines in antiaxial view (Fig. 11G, 11H). Hind tarsus 5-segmented, length ratio of each segment = 1:1:1:1:6.

Fig. 11.

Scanning electron images of male Sycoscapter monticola sp. nov. A, Antenna; B, Maxillary palps and labial palps; C, Left fore tibia, axial; D, Right tibia, antiaxial; E, Left mid tibia, axial; F, Right mid tibia, antiaxial; G, Right hind tibia, axial; H, Left hind tibia, antiaxial. Scale bar = 0.03 mm.

Metasoma: Abdomen L = 0.67 mm.

Host: Ficus nervosa Heyne ex Roth.

Distubution: Taiwan: Keelung, New Taipei, Yilan, Taitung; China: Hainan.

Etymology: This species is named after the mountain habitat of its host fig tree.

Diagnosis: This species has a subhexagonal head shape in males that shows no similarity with any other described species.

Remarks: This species utilizes shares the same host species with an Indian congener, S. vijayaii Priyadasanan, but the two species can be distinguished by the characters in female including the ratio of POL to OOL (4.84 in S. monticola vs. 11 in S. vijayaii), the ratio of ovipositor L to metasoma L (6.08 in S. monticola vs. 7 in S. vujayaii); in male including the head shape (subhexagonal in S. monticola vs. rectangular in S. vijayaii), the claval segments (3 in S. monticola vs. 2 in S. vijayaii).

Sycoscapter ishiianus Chou & Tzeng sp. nov.

(Figs. 12, 13, 14)

urn:lsid:zoobank.org:act:E98F9E4A-0B39-4683-84D5-26F485590FFD

Type locality: South Dist., Taichung, Taiwan.

Material examined: Holotype: 1♀, South Dist. (24.128055, 120.678623), Taichung City, ex Ficus subpisocarpa Gagnep., 31-VII-2023, leg. P. A. Chou (NCHU). Paratypes: 1♂, South Dist. (24.128055, 120.678623), Taichung City, ex Ficus subpisocarpa Gagnep., 31-VII-2023, leg. P. A. Chou (NCHU); 1♂1♀, Shuangliu (22.217694, 120.803907), Pingtung, ex Ficus subpisocarpa Gagnep., 8-Ⅱ-2021, leg. C. Y. Huang (TARI). Others: Taiwan: 1♂1♀, Lover’s Lake Park (25.156796, 121.705576), Keelung, ex Ficus subpisocarpa Gagnep., 24-XI-2020, leg. P. A. Chou (NCHU); 1♂1♀, Tianmu (25.118908, 121.532423),

Taipei City, ex Ficus subpisocarpa Gagnep., 19-Ⅵ2022, leg. Y. R. Fang (NCHU); 1♂1♀, Shen’ao (25.127480, 121.816726), New Taipei City, ex Ficus subpisocarpa Gagnep., 19-VIII-2022, leg. P. A. Chou (NCHU); 1♂1♀, Anping (22.995227, 120.164240),

Tainan, ex Ficus subpisocarpa Gagnep., 2-IX2018, leg. P. A. Chou (NCHU); 1♂1♀, Frog Rock Trail (21.942526, 120.799618), Pingtung, ex Ficus subpisocarpa Gagnep., 24-XI-2020, leg. P. A. Chou (NCHU); 1♂1♀, Carp Mountain Park (22.753445, 121.144535), Taitung, ex Ficus subpisocarpa Gagnep., 2-IX-2022, leg. P. A. Chou (NCHU); 1♂1♀, Penghu Visitor Center (23.557232, 119.608105), Penghu, ex Ficus subpisocarpa Gagnep., 3-VI-2019, leg. P. A. Chou (NCHU); 1♂1♀, Kinhu Junior High School (24.437888, 118.420643), Kinmen, ex Ficus subpisocarpa Gagnep., 23-X-2021, leg. P. A. Chou (NCHU); Japan: 1♂1♀, Iriomote (24.384750, 123.893395), Okinawa, ex Ficus subpisocarpa Gagnep., 8-VII-2018, leg. P. A. Chou (NCHU).

Description: Female: Whole L = 4.43–4.65 mm with body L = 1.22–1.24 mm and ovipositor sheath L = 3.19–3.41 mm. Body metallic green (Fig. 12C). Compound eyes pale red (Fig. 12A). Antenna black except for the yellow basal part of the scape (Fig. 12I). Legs yellow (Fig. 12J, 12L, 12N); basal part of hind coxa and middle of hind femur black in antiaxial view (Fig. 12N).

Fig. 12.

Sycoscapter ishiianus sp. nov. A, Female head, front; B, Female mesosoma, dorsal; C, Female habitus, lateral; D, Male habitus, lateral; E, Male head, dorsal; F, Male mesosoma, dorsal; G, Female left mandible, ventral; H, Male left mandible, dorsal; I, Female antenna; J, Female right foreleg; K, Male right foreleg; L, Female right mid leg; M, Male right mid leg; N, Female right hind leg; O, Male right hind leg; P, Female forewing. Scale bar = 0.1 mm if no number is noted.

Head: Obcordate in front view (Fig. 12A). H = 0.26 mm, W over compound eyes = 0.37 mm; W between compound eyes = 0.21 mm. Compound eye H 1.47× malar space L, and 2.44× compound eyes W. POL 4.95× OOL. Clypeus margin with a blunt projection in the middle (Fig. 13A). Face with raised reticulation but antennal scrobes psilate (Fig. 12A). Mandible bidentate (Fig. 12G). Maxillary palp 3-segmented, length ratio = 3:4:5 (Fig. 13B). Labial palp 2-segmented, length ratio = 3:2 (Fig. 13B). The distance between toruli 0.3× clypeus margin. Antennal formula 11253 and L = 0.55 mm; length ratio of scape, pedicel, anelli, funicle and clava = 14:4:1:20:10 (Fig. 12I). Scape L 4.57× W, with sparse trichoid sensillae (Fig. 13C). Pedicel L 1.08× W, with sparse trichoid sensillae (Fig. 13C). Both anelli equal in length and the second one wider (Fig. 13C). All funicular segments equal in length; the first funicular segment L 0.98× W, with 3 multiporous placoid sensillae and 7 chaetica sensillae in antiaxial view; the chaetica sensilla longer than the funicular segment (Fig. 13C). Claval segments slightly wider than funicular segments; the first claval segment L 0.89× W, with 3 multiporous placoid sensillae and 7 chaetica sensillae in antiaxial view.

Fig. 13.

Scanning electron images of female Sycoscapter ishiiaus sp. nov. A, Toruli and epistomal margin; B, Maxillary palps and labial palps; C, Anelli and the first funiculus; D, Scutellum; E, Left fore tibia, axial; F, Right tibia, antiaxial; G, Left mid tibia, axial; H, Right mid tibia, antiaxial; I, Right hind tibia, axial; J, Left hind tibia, antiaxial. Scale bar = 0.03 mm.

Mesosoma: Mesosoma L = 0.46 mm, W = 0.36 mm, length ratio of pronotum, scutum, scutellum and propodeum = 2:4:6:1. Pronotum, scutum and scutellum with raised reticulation but propodeum psilate in dorsal view (Fig. 12B). Pronotum with collar in ventral view. Scutum with incomplete notauli (Fig. 12B). Scutellum nearly as wide as long, punctures of reticulation lengthened longitudinally (Fig. 13D). Metanotum strongly compressed and the middle covered by scutellum. Propodeum with two longitudinal keels. Forewing L = 1.19 mm, W = 0.53 mm, with 9–13 setae below the marginal vein; length ratio of submarginal vein, marginal vein, postmarginal vein and stigmal vein = 5:3:4:2 (Fig. 12P). Hind wing L = 0.80 mm, W = 0.16 mm; length ratio of submarginal vein and marginal vein = 2:3. Foreleg L = 0.75 mm; length ratio of coxa, trochanter, femur, tibia and tarsus = 3:2:5:4:3 (Fig. 12J).

Fore tibia with a curve, bidentate spur reaching the apex of first tarsomere; 2 spines beside spur in axial view and 1 spine in antiaxial views (Fig. 13E, 13F). Fore tarsus 5-segmented, length ratio of each segment = 4:3:3:2:7. Mid leg L = 0.81 mm; length ratio of coxa, trochanter, femur, tibia and tarsus = 1:1:3:4:3 (Fig. 12L). Mid tibia with a straight spur; spur L 0.5× the first tarsomere L; 2 spines beside spur in axial view but 2 spines in antiaxial view (Fig. 13G, 13H). Mid tarsus 5-segmented, length ratio of each segment = 7:4:3:2:4. Hind leg L = 1.04 mm; length ratio of coxa, trochanter, femur, tibia and tarsus = 3:1:3:4:3 (Fig. 12N). Hind tibia with a straight spur; spur L 0.5× the first tarsomere L; 23–25 teeth in axial view and 2 spines beside spur in antiaxial view (Fig. 13I, 13J). Hind tarsus 5-segmented, length ratio of each segment = 6:4:3:2:5.

Metasoma: Abdomen without ovipositor sheath L = 0.73 mm.

Male: L = 1.69–1.75 mm. Body brown (Fig. 12D). Eyes black (Fig. 12E). Mandible dark brown (Fig. 12H). Antenna pale yellow (Fig. 12E). Legs brown (Fig. 12K, 12M, 12O).

Head: Long rectangular in dorsal view (Fig. 12E). L without mandible = 0.43 mm, W = 0.39 mm. Mandible L = 0.28 mm, W = 0.15 mm. Mandible falcate with a fine tooth at the middle (Fig 12H). Clypeus margin concave in the middle. Maxillary palp 4-segmented, length ratio = 3:2:1:2 (Fig. 14B). Labial palp 2-segmented, length ratio = 3:1 (Fig 14B). Compound eye L 3× W. Malar space L 1.73× compound eye L. Toruli close to clypeus margin, with a ridge in the middle. Antennal formula 11153 and L = 0.39 mm; length ratio of scape, pedicel, anelli, funicle and clava = 14:7:1:8:6. Scape L 4.76× W, with sparse trichoid sensillae (Fig. 14A). Pedicel L 3.7× W, with sparse trichoid sensillae (Fig. 14A). The first and third funicular segments swollen, L 0.81× W; other funicular segments L 0.88× W; all funicular segments with trichoid sensillae (Fig. 14A). Claval segments wider than the swollen funicular segments; the first claval segment L 1.03× W, with trichoid sensillae and multiporus placoid sensillae (Fig. 14A).

Mesosoma: Subpentagon in dorsal view (Fig. 12F). L = 0.51 mm, W = 0.36 mm; length ratio of pronotum and the fused tergum = 3:2 Pronotum with collar in ventral view. Mesonotum, metanotum and propodeum fused in dorsal view (Fig. 12F). Rudimentary wing vestige present, L = 0.33 mm (Fig. 12F). Foreleg L = 0.91 mm; length ratio of coxa, trochanter, femur, tibia and tarsus = 3:1:4:2:2 (Fig. 12K). Fore tibia with a slightly curve, bidentate spur reaching the fourth tarsomere; 7 spines in axial view and 8 spines in antiaxial view (Fig. 14C, 14D). Fore tarsus 5-segmented, length ratio of each segment = 1:1:1:1:5. Mid leg L = 0.83 mm; length ratio of coxa, trochanter, femur, tibia and tarsus = 2:1:2:2:2 (Fig. 12M). Mid tibia with a straight spur reaching the second tarsomere; 6–9 spines in axial view and 7–8 spines in antiaxial view (Fig. 14E, 14F). Mid tarsus 5-segmented, length ratio of each segment = 1:1:1:1:5. Hind leg L = 1.02 mm; length ratio of coxa, trochanter, femur, tibia and tarsus = 4:1:3:3:3 (Fig. 12O). Hind tibia with a straight spur reaching the third tarsomere; 10–13 spines in axial view and 8–11 spines in antiaxial view (Fig. 14G, 14H). Hind tarsus 5-segmented, length ratio of each segment = 1:1:1:1:5.

Fig. 14.

Scanning electron images of male Sycoscapter ishiianus sp. nov. A, Antenna; B, Maxillary palps and labial palps; C, Left fore tibia, axial; D, Right tibia, antiaxial; E, Left mid tibia, axial; F, Right mid tibia, antiaxial; G, Right hind tibia, axial; H, Left hind tibia, antiaxial. Scale bar = 0.03 mm.

Metasoma: Abdomen L = 0.47 mm.

Host: Ficus subpisocarpa Gagnep.

Distribution: Taiwan: Keelung, Taipei, New Taipei, Taichung, Tainan, Pingtung, Taitung, Penghu, Kinmen; Japan: Iriomote island.

Etymology: This species is named in honor of Tei Ishii, who contributed greatly to fig wasp taxonomy in East Asia.

Diagnosis: This species is similar to S. infectorius but can be distinguished from the characters in female including the ratio of ovipositor L to metasoma L (4.37 in S. ishiianus vs. 5.6 in S. infectorius), the maxillary palp segment (four in S. ishiianus vs, three in S. infectorius); in male including spur on fore tibia (not exceeding the last tarsomere in S. ishiianus vs. doing so in S. infectorius).

Sycoscapter littoralis Chou & Tzeng sp. nov.

(Figs. 15, 16, 17)

urn:lsid:zoobank.org:act:64C41C6C-F6CB-4F84-8C10-

857B3D093D7E

Type locality: Dawu, Taitung, Taiwan.

Material examined: Holotype: 1♀, Dawu (22.309822, 120.889147), Taitung, ex Ficus caulocarpa (Miq.) Miq., 3-IX-2022, leg. P. A. Chou (NCHU). Paratypes: 1♂, Dawu (22.309822, 120.889147), Taitung, ex Ficus caulocarpa (Miq.) Miq., 3-IX-2022, leg. P. A. Chou (NCHU); 1♂1♀, Shen’ao (25.128355, 121.813439), New Taipei City, ex Ficus caulocarpa (Miq.) Miq., 2-X-2022, leg. P. A. Chou (TARI). Others: 1♂1♀, Taitung Seashore Park (22.751577, 121.161233), Taitung, ex Ficus caulocarpa (Miq.) Miq., 2-IX-2022, leg. P. A. Chou (NCHU); 1♂1♀, Kenting Forest Recreation Park (21.963324, 120.812599), Pintong, ex Ficus caulocarpa (Miq.) Miq., 19-IV-2023, leg. P. A. Chou (NCHU); 1♂1♀, Lanyu (22.035262, 121.563452), Taitung, ex Ficus caulocarpa (Miq.) Miq., 4-X-2020, leg. P. A. Chou (NCHU).

Description: Female: Whole L = 2.99–3.25 mm with body L = 0.93–1.03 mm and ovipositor sheath L = 2.06–2.22 mm. Body metallic green (Fig. 15C). Compound eyes pale red (Fig. 15A). Antenna black except for the yellow basal part of the scape (Fig. 15I). Legs yellow (Fig. 15J, 15L, 15N); middle of hind femur slightly black (Fig. 15L); basal part of hind coxa and middle of hind femur black in antiaxial view (Fig. 15N).

Fig. 15.

Sycoscapter littoralis sp. nov. A, Female head, front; B, Female mesosoma, dorsal; C, Female habitus, lateral; D, Male habitus, lateral; E, Male head, dorsal; F, Male mesosoma, dorsal; G, Female left mandible, ventral; H, Male left mandible, dorsal; I, Female antenna; J, Female right foreleg; K, Male right foreleg; L, Female right mid leg; M, Male right mid leg; N, Female right hind leg; O, Male right hind leg; P, Female forewing. Scale bar = 0.1 mm if no number is noted.

Head: Rounded in front view (15A). H = 0.24 mm, W over compound eyes = 0.28 mm; W between compound eyes = 0.19 mm. Compound eye H 1.41× malar space, and 3.05× compound eyes W. POL 3.12× OOL. Clypeus margin with a blunt projection in the middle (Fig. 16A). Face with raised reticulation but antennal scrobes psilate (Fig. 15A). Mandible bidentate (Fig. 15G). Maxillary palp 3-segmented, length ratio of others = 2:4:3 (Fig. 16B). Labial palp 2-segmented, length ratio = 3:2 (Fig. 16B). The distance between toruli 0.27× clypeus margin. Antennal formula 11253 and L = 0.36 mm; length ratio of scape, pedicel, anelli, funicle and clava = 14:4:1:20:10 (Fig. 15I). Scape L 4× W, with sparse trichoid sensillae (Fig. 16C). Pedicel L 1.25× W, with sparse trichoid sensillae (Fig. 16C). Both anelli equal in length and the second one wider (Fig. 16C). All funicular segments equal in length; the first funicular segment L 0.82× W, with 3 multiporous placoid sensillae and 3 chaetica sensillae in antiaxial view. The chaetica sensilla longer than funicular segment (Fig. 16C). Claval segments slightly wider than funicular segments; the first claval segment L 1× W, with 2 multiporous placoid sensillae and 4 chaetica sensillae in antiaxial view.

Fig. 16.

Scanning electron images of female Sycoscapter littoralis sp. nov. A, Toruli and epistomal margin; B, Maxillary palps and labial palps; C, Anelli and the first funiculus; D, Scutellum; E, Left fore tibia, axial; F, Right tibia, antiaxial; G, Left mid tibia, axial; H, Right mid tibia, antiaxial; I, Right hind tibia, axial; J, Left hind tibia, antiaxial. Scale bar = 0.03 mm.

Mesosoma: Mesosoma L = 0.43 mm, W = 0.27 mm; length ratio of pronotum, scutum, scutellum and propodeum = 2:3:4:1. Pronotum, scutum and scutellum with raised reticulation but propodeum psilate in dorsal view (Fig. 15B). Pronotum with collar in ventral view. Scutum with incomplete notauli (Fig. 15B). Scutellum nearly as wide as long, punctures of reticulation lengthened longitudinally (Fig. 16D). Metanotum strongly compressed and the middle covered by scutellum. Propodeum with two longitudinal keels. Forewing L = 0.86 mm, W = 0.37 mm, with 9-10 setae below the marginal vein; length ratio of submarginal vein, marginal vein, postmarginal and stigmal vein = 5:3:4:2 (Fig. 15P). Hind wing L = 0.54 mm, W = 0.12 mm; length ratio of submarginal vein and marginal vein L = 2:3. Foreleg L = 0.57 mm; length ratio of coxa, trochanter, femur, tibia and tarsus = 3:2:5:4:3 (Fig. 15J). Fore tibia with a curve, bidentate spur reaching the first tarsomere; 2 spines beside spur in axial view and 1 spine in antiaxial views (Fig. 16E, 16F). Fore tarsus five segments, length ratio of each segment = 2:2:1:1:3. Mid leg L = 0.59 mm; length ratio of coxa, trochanter, femur, tibia and tarsus = 1:1:3:4:3 (Fig. 15L). Mid tibia with a straight spur; spur L 0.5× the first tarsomere L; 1 spine beside spur in axial view but no spine in antiaxial view (Fig. 16G, 16H). Mid tarsus five segments, length ratio of each segment = 7:4:3:2:5. Hind leg L = 0.82 mm; length ratio of coxa, trochanter, femur, tibia and tarsus L = 3:1:3:5:3 (Fig. 15N). Hind tibia with a straight spur; spur L 0.5× the first tarsomere L; 25–27 teeth in axial view and 2 spines beside spur in antiaxial view (Fig. 16I, 16J). Hind tarsus five segments, length ratio of each segment = 7:4:3:2:5.

Metasoma: Abdomen without ovipositor sheath L = 0.59 mm.

Male: L = 1.34–1.43 mm. Body brown (Fig. 15D). Eyes black (Fig. 15E). Mandible dark brown (Fig. 15H). Antenna pale yellow (Fig. 15E). Legs brown (Fig. 15K, 15M, 15O).

Head: Long rectangular in dorsal view (Fig. 15E). L without mandible = 0.42 mm, W = 0.42 mm. Mandible L = 0.28 mm, W = 0.11 mm. Mandible falcate with a fine tooth at the middle (Fig 15H). Clypeus margin concave in the middle. Maxillary palp 4-segmented, length ratio = 3:3:1:2 (Fig. 17B). Labial palp 2-segmented, length ratio = 2:3 (Fig 17B). Compound eye L 3× W. Malar space L 1.95× compound eye L. Toruli close to clypeus margin, with a ridge in the middle. Antennal formula 11153 and L = 0.39 mm; length ratio of scape, pedicel, anellus, funicle and clava = 11:7:1:8:7. Scape L 4.36× W, with sparse trichoid sensillae (Fig. 17A). Pedicel L 2.68× W, with sparse trichoid sensillae (Fig. 17A). The first and third funicular segments swollen, L 0.8× W; other funicular segments L 0.72× W; all funicular segments with trichoid sensillae (Fig. 17A). Claval segments as wide as the swollen funicular segments; the first claval segment L 1.18× W, with trichoid sensillae and multiporus placoid sensillae (Fig. 17A).

Mesosoma: Oblong in dorsal view (Fig. 15F); L = 0.44 mm, W = 0.31 mm; length ratio of pronotum and the fused tergum = 2:1. Pronotum with collar in ventral view. Mesonotum, metanotum and propodeum fused in dorsal view (Fig. 15F). Rudimentary wing vestige present, L = 0.29 mm (Fig. 15F). Foreleg L = 1.52 mm; length ratio of coxa, trochanter, femur, tibia and tarsus = 3:1:3:2:2 (Fig. 15K). Fore tibia with a slightly curve, bidentate spur reaching the fourth tarsomere; 4–5 spines in axial view and 9–11 spines in antiaxial view (Fig. 17C, 17D). Fore tarsus 5-segmented, length ratio of each segment = 2:1:1:1:7. Mid leg L = 0.68 mm; length ratio of coxa, trochanter, femur, tibia and tarsus L = 2:1:2:2:2 (Fig. 15M). Mid tibia with a straight spur reaching the second tarsomere; 8–11 spines in axial view and 7–10 spines in antiaxial view (Fig. 17E, 17F). Mid tarsus five segments, length ratio of each segment = 1:1:1:1:5. Hind leg L = 0.90 mm; length ratio of coxa, trochanter, femur, tibia and tarsus L = 4:1:4:4:3 (Fig. 15O). Hind tibia with a straight spur reaching the third tarsomere; 7–8 spines in axial view and 15 spines in antiaxial view (Fig. 17G, 17H). Hind tarsus five segments, length ratio of each segment = 1:1:1:1:4.

Fig. 17.

Scanning electron images of male Sycoscapter littoralis sp. nov. A, Antenna; B, Maxillary palps and labial palps; C, Left fore tibia, axial; D, Right tibia, antiaxial; E, Left mid tibia, axial; F, Right mid tibia, antiaxial; G, Right hind tibia, axial; H, Left hind tibia, antiaxial. Scale bar = 0.03 mm.

Metasoma: Abdomen L = 0.38 mm.

Host: Ficus caulocarpa (Miq.) Miq.

Distribution: Taiwan: New Taipei, Taitung, Pintong.

Etymology: This species is named after the coastal habitats of its host fig tree.

Diagnosis: 1. This is species is similar to S. infectorius Joseph but can be distinguished from the characters in female including the ratio of POL to OOL (5.35 in S. littoralis vs. 6.7 in S. infectorius), the seta number on forewing (9–10 in S. littoralis vs. 15 in S. infectorius), ratio of ovipositor L to metasoma L (3.76 in S. littoralis vs. 5.6–6 in S. infectorius); in male including the spur on fore tibia (not exceeding the last tarsomere in S. littoralis vs. doing so in S. infectorius).

2. This species is also similar to S. ishiianus sp. nov. but can be distinguished from the characters in female including the head shape (rounded in S. littoralis vs. subtriangle in S. ishiianus), the maxillary palp segment (three in S. littoralis vs. four in S. ishiianus); in male including the pronotum shape (oblong in S. littoralis vs. subpentagonal in S. ishiianus).

Key to the Sycoscpater species associated with monoecious figs in Taiwan

1. Fully winged; body metallic green (Figs. 3C; 6C; 9C; 12C; 15C) ....................................................................................... Female, 2

- Wings reduced to filiform vestige; body yellowish brown (Figs. 3F; 6F; 9F; 12F; 15F) ....................................................... Male, 6

2. Scape all yellowish (Fig. 3I); punctures of reticulation on scutellum rounded (Fig. 4D) ...................................... S. gajimaru

- Scape black with slight yellow on the basal part (Figs. 6I; 9I; 12I; 15I); punctures of reticulation on scutellum lengthened longitudinally (Figs. 7D; 10D; 13D; 16D) ................................. 3

3. POL almost 7× OOL (Fig. 6A); Scutellum L 4× pronotum L (Fig. 6B) ......................................................................... S. piceoscapus

- POL < 5× OOL (Figs. 9A; 12A; 15A); Scutellum L 2 or 3× pronotum L (Figs. 9B; 12B; 15B) .............................................. 4

4. Head H 3.5× W over compound eyes (Fig. 12A); Scutellum L 3× pronotum L (Fig. 12B) ............................................... S. ishiianus

- Head H at least 4× W over compound eyes (Figs. 9A; 15A); Scutellum L 2× pronotum L (Figs. 9B; 15B) ............................. 5

5. Antennal scrobes psilate (Fig. 9A); middle part of hind femur without black spot in antiaxial view (Fig. 9N) ......... S. monticola

- Antennal scrobes with raised reticulation (Fig. 15A); middle part of hind femur with black spot in antiaxial view (Fig. 15N) .......... ..................................................................................... S. littoralis

6. Scape L 2.5× W (Fig. 5A); compound eye L 2.5× W (Fig. 3E) ......................................................................................... S. gajimaru

- Scape L at least 3× W (Figs. 8A; 11A; 14A; 17A); compound eye L at least 3× W (Figs. 6E; 9E; 12E; 15E) ................................... 7

7. Head long ovate (Fig. 6E); compound eye L 3.5× W (Fig. 6E) .................................................................................... S. piceoscapus

- Head subhexagonal or long rectangular (Figs. 9E; 12E; 15E); compound eye L 3× W (Figs. 9E; 12E; 15E) ............................. 8

8. Head subhexagonal (Fig. 9E); anterior margin of pronotum convex obviously (Fig. 9F) ...................................... S. monticola

- Head long rectangular (Figs. 12E; 15E); anterior margin of pronotum not convex obviously (Figs. 12F; 15F) ...................... 9

9. Mesosoma subpentagonal (Fig. 12F); pronotum L 1.5× L of the fused tergum (Fig. 12F) .............................................. S. ishiianus

- Mesosoma ovate (Fig. 15F); pronotum L 2× L of the fused tergum (Fig. 15F) ....................................................... S. littoralis

DISCUSSION

In this study, we collected all six monoecious fig species in Taiwan and documented the presence of five Sycoscapter wasp species associated with these figs with the exception of F. pubinervis, the rarest monoecious fig species in Taiwan. Notably, a previous study (Segar et al. 2012) had reported the association of one Sycoscapter wasp with F. pubinervis. The absence of this Sycoscapter wasp in our collection could be attributed to the limited distribution of F. pubinervis in Taiwan. Wang et al. (2015) documented a decline in the species richness of fig wasps associated with F. microcarpa along latitude or altitude, indicating that certain wasp species may struggle to colonize figs in marginal distribution areas.

Although the COI gene has been considered less reliable for species delimitation in fig wasps owing to rampant heteroplasmy (Xiao et al. 2010; Li et al. 2021), the phylogenetic trees based on COI+28S combined data and the results of PTP method exhibited a consistent trend, supporting the existence of five Sycoscapter species associated with monoecious figs in Taiwan. This finding was also supported by the substantial genetic gaps among all Sycoscapter species in this study. Moreover, aligning with the wide distribution of their host fig trees, most of these Sycoscapter wasps exhibited broad geographic ranges, extending from China to Taiwan or from Taiwan to the Ryukyu Islands, Japan. Although a direct observation of Sycoscapter wasp dispersal ability is lacking, it is reasonable to assume that they possess a wider distribution range compared with agaonid wasps, which are known to disperse up to 160 km via wind (Ahmed et al. 2009; Sutton et al. 2016).

Our findings revealed that both S. gajimaru and S. piceoscapus used F. microcarpa and F. benjamina var. bracteata as host species. Given the close relationship between these two Ficus species and their similar fig sizes during receptive and developing phases (4–7 mm in F. microcarpa vs. 5–7 mm in F. benjamina var. bracteata; Tzeng 2004), the transition between these two host figs appears to be relatively unrestricted, likely owing to minimal impedance from the fig wall (Fan et al. 2019). Furthermore, the use of multiple fig species by sycoryctina wasps has been observed in numerous studies (Silvieus et al. 2008; McLeish et al. 2012), suggesting that flexible host specificity is not uncommon in this wasp group.

In accordance with Bouček et al. (1981) and Pramanik and Dey (2019), several female-specific characters have been used to differentiate Sycoscapter species, including POL/OOL ratio, the number of setae on the forewing, the ratio of marginal vein to stigma vein L, and the ratio of ovipositor L/metasoma L. However, among these characters, the number of setae on the forewing has been reported to be highly variable (Wiebes 1967), with variations observed not only between individuals in the same population but also within the wings of the same individual. In contrast, the POL/OOL character appears to be reliable for the identification of Sycoscapter wasps, as it has exhibited effectiveness in not only the studied Sycoscapter wasps but also in other pteromalid groups (Graham 1969; Bouček and Rasplus 1991). In addition, the taxonomic value of spine or tooth number on the legs was examined in this study as it had been regarded as a character to identify species in another fig wasp genus (Ulenberg and van Pelt 1985). Our results revealed spine number on legs of males might be used as a character at the morpho-group level, but not at species level due to its variation between individuals of a species. Although several taxonomic studies have described Sycoscapter species based solely on females (Walker 1871; Risbec 1956), this approach can lead to taxonomic challenges, especially when species exhibit substantial sexual dimorphism (Walker 1871; Westwood 1883), as observed in the present study. Interestingly, our findings suggest that male characters may have greater taxonomic value, particularly the varied and distinct male head shapes. Despite reports of male polymorphism in fig wasps being common (Murray 1990; Bean and Cook 2001; Jousselin et al. 2005), our observations indicate polymorphism in male heads was limited to size variation among the five Sycoscapter species, underscoring the potential value of male head shape as a taxonomic character in this study.

Although this study focused exclusively on species associated with monoecious figs, the shared wing vestige among them does not necessarily imply that they form a monophyletic group compared with species associated with functional dioecious figs. Despite the terms ‘rudimentary wing vestige’ or ‘remnant wing’ (Westwood 1883; Wiebes 1966), it is unlikely that this structure serves as a mere vestige, given the presence of numerous fine hairs that may serve sensory functions as male individuals navigate the internal galls and seeds of a fig. The differences in internal microhabitats between monoecious and functional dioecious figs have been documented in various studies (Kerdelhué and Rasplus 1996; Weiblen 2000), with the most notable distinction being the layer structure composed of galls and seeds, which forms multiple layers in monoecious figs and a single layer in functional dioecious figs (Kerdelhué and Rasplus 1996). Similarly, the presence of the wing vestige in male wasps of the genera Otitesella and Walkerella, which belong to the pteromalid tribe Otitesellini and are primarily associated with monoecious fig trees (Jousselin et al. 2006; Ma et al. 2013), suggests that these males may have evolved similar habits or behaviors inside their native figs. Therefore, the wing vestige is more likely an adaptive convergent character rather than a synapomorphic character.

This study, including a thorough collection effort, represents the first comprehensive taxonomic assessment of Sycoscapter wasps associated with monoecious figs in Taiwan. Given the reported keystone status of fig species (Mackay et al. 2018), it is crucial to identify species composition in fig-wasp communities and understand their interactions within multitrophic ecosystems. Although taxonomic studies of Sycoscapter species associated with functional dioecious figs remain to be conducted, this study not only contributes to the knowledge of chalcidoid fauna in Taiwan but also provides insights into the mechanism underlying the maintenance of this intricate ecosystem.

CONCLUSIONS

Wasps of the genus Sycoscapter (Hymenoptera: Pyeromalidae) associated with monoecious Ficus species in Taiwan were investigated. Both phylogenetic and morphological results indicated presence of five species among those wasps, including four new species: S. piceoscapus sp. nov., S. monticola sp. nov., S. ishiianus sp. nov. and S. littoralis sp. nov. This discovery not only records new members of Taiwanese chalcid fauna but also provides insight into fig-wasp symbiosis.

Supplementary materials

Table S1.

Monoecious Ficus species in Taiwan and their distributions according to Flora of Taiwan Vol. 2 (2nd edition).

Fig. S1.

Phylogenetic tree of the Sycoscapter species associated with monoecious figs in Taiwan and other congeners based on 28S genes. The values at the nodes are the ultrafast bootstraps and posterior possibilities for maximum likelihood (ML) and Bayesian inference (BI) analyses, respectively.

Fig. S2.

Lectotype of Sycoscapter gajimaru (Ishii). A, female specimen; B, label.