Revision of the genus Lechytia Balzan, 1892 (Pseudoscorpiones, Chthoniidae) from China, with descriptions of two new species

Jianzhou Sun; Xiangbo Guo; Feng Zhang

doi:10.3897/BDJ.12.e122612

. 2024 Apr 19;12:e122612. doi: 10.3897/BDJ.12.e122612

Revision of the genus Lechytia Balzan, 1892 (Pseudoscorpiones, Chthoniidae) from China, with descriptions of two new species

Jianzhou Sun ^1,², Xiangbo Guo ^1,², Feng Zhang ^1,^2,^✉

PMCID: PMC11055984 PMID: 38680523

Abstract

Background

The hoffi species-group previously comprised only two species, Lechytiahoffi Muchmore, 1975 and Lechytiayulongensis Zhang and Zhang, 2014, of which L.yulongensis is distributed in China.

New information

Three species of the genus Lechytia are described from China: Lechytiaacutidentata sp. nov. and Lechytiadepressidentata sp. nov. from Xizang Autonomous Region and L.yulongensis from Yunnan Province. The female of L.yulongensis is reported for the first time. In addition, a key to the hoffi species-group is provided.

Keywords: new species, Lechytiinae, taxonomy, Xizang

Introduction

The pseudoscorpion genus Lechytia Balzan, 1892 was established for a Neotropic species, Lechytiachthoniiformis (Balzan 1887), which was originally placed in the genus Roncus L. Koch, 1873 (Balzan 1892). From then on, Lechytia belonged to Chthoniidae Daday, 1889, until Harvey (1992) elevated it to the family level due to the lacking of an elliptical areole on the rallum and the short inter-maxillary jugum. Subsequently, it was reduced to a subfamily (Lechytiinae) within Chthoniidae, based on phylogenetic analyses using transcriptome data (Benavides et al. 2019). The most peculiar diagnostic feature of Lechytiinae is the trichobothria eb and esb situated on the dorsum of the chelal hand, while these trichobothria are situated at the base of the fixed chelal finger in all other members of Chthoniidae (Harvey 2006, Christophoryová and Krajčovičová 2020).

Currently, there are 26 reported Lechytia species widespread in most parts of the world, with six species in Africa, seven in Asia (including the Pacific), 11 in the Americas (including one fossilised species) and two in Oceania (WPC 2024). Lechytia contains two species-groups: arborea species-group for six species from the Americas, Oceania and the Pacific and hoffi species-group for two species from North America and Asia (Muchmore 1975, Muchmore 2000, Harvey 2006, Zhang and Zhang 2014, Christophoryová and Krajčovičová 2020). The remaining 18 species are not placed in the two known species-groups. The hoffi (arborea) species-group is diagnosed as follows: well-developed (strongly reduced) chelal teeth, simple (bifurcate) distal seta on pedipalpal coxa, tergite XI with chaetotaxy T2T (1T2T1) and male galea nearly as well developed as in female (male galea reduced).

At present, only one Lechytia species, L.yulongensis Zhang and Zhang, 2014, has been reported from China (Zhang and Zhang 2014), which belongs in the hoffi species-group together with L.hoffi. Herein, two new Lechytia species from China are described. In addition, the female of L.yulongensis is reported for the first time.

Materials and methods

Specimen preparation and examination. The specimens examined for this study are preserved in 75% ethyl alcohol and in a refrigerator at -20°C and deposited in the Museum of Hebei University (MHBU) (Baoding, China). Photographs, drawings and measurements were taken using a Leica M205A stereo-microscope equipped with a Leica DFC550 camera and the Inkscape software (Ver. 1.0.2.0). Detailed examination was carried out with an Olympus BX53 general optical microscope. All images were edited and formatted using Adobe Photoshop 2017.

Preparation for scanning electron microscopy (SEM). The samples were placed in 95% ethanol for one hour, followed by placement in 100% ethanol and finally switched to fresh 100% ethanol overnight. Each sample was proceeded to critical point drying (POLARON E3000), using Carbon Dioxide (CO₂) as transitional fluid. The specimen was processed as above and then the sample was photographed using a SEM.

Terminology. Terminology and measurements follow Chamberlin (1931) with some small modifications to the terminology of trichobothria (Harvey 1992, Judson 2007) and chelicera (Judson 2007). The chela and legs are measured in lateral view and others are taken in dorsal view. All measurements are given in mm unless noted otherwise. Proportions and measurements of chelicerae, carapace and pedipalps correspond to length/breadth and those of legs to length/depth.

The following abbreviations are used in the text: for the chelal trichobothria: b = basal; sb = sub-basal; st = subterminal; t = terminal; ib = interior basal; isb = interior sub-basal; ist = interior sub-terminal; it = interior terminal; eb = exterior basal; esb = exterior sub-basal; est = exterior sub-terminal; et = exterior terminal. For additional abbreviations: dx, duplex trichobothria.

Taxon treatments

Lechytia acutidentata sp. nov.

CDF320A8-04B4-589F-87D4-E933A44F33D9

34A4EC3B-9F38-47B3-96E7-6289B5C700BA

Materials

Type status: Holotype. Occurrence: recordedBy: Xiangbo Guo, Bo Liu & Haibin Zhang; sex: female; lifeStage: adult; occurrenceID: 3E280ECF-CA68-54EE-A007-D55C009D6828; Taxon: scientificName: Lechytiaacutidentata; Location: country: China; stateProvince: Xizang Autonomous Region; county: Jilong; locality: Jilong Town, Rema Village, under bark; verbatimElevation: 3272 m; verbatimCoordinates: 28.455680°N, 85.196614°E; Identification: identifiedBy: Jianzhou Sun; Event: eventID: HBUARA#2023-880; year: 2023; month: August; day: 2; Record Level: institutionID: the Museum of Hebei University (MHBU); institutionCode: Ps.-MHBU-XZ2023080201
Type status: Paratype. Occurrence: recordedBy: Xiangbo Guo, Bo Liu & Haibin Zhang; sex: 1 male, 31 females; lifeStage: adult; occurrenceID: 2053BC16-16DC-5FC4-A9C5-76DA95B44FEC; Taxon: scientificName: Lechytiaacutidentata; Location: country: China; stateProvince: Xizang Autonomous Region; county: Jilong; locality: Jilong Town, Rema Village, under bark; verbatimElevation: 3272 m; verbatimCoordinates: 28.455680°N, 85.196614°E; Identification: identifiedBy: Jianzhou Sun; Event: eventID: HBUARA#2023-880; year: 2023; month: August; day: 2; Record Level: institutionID: the Museum of Hebei University; institutionCode: male (Ps.-MHBU-XZ2023080202) and 31 females (Ps.-MHBU-XZ2023080203–033)

Description

Females (holotype and paratypes) (Fig. 1B, Fig. 2A–H, K and Figs 3, 4A–D).

Figure 1. — *Lechytiaacutidentata* sp. nov. A Paratype male (dorsal view); B Holotype female (dorsal view). Scale bars: 0.50 mm.

Figure 2. — *Lechytiaacutidentata* sp. nov., holotype female (A–H, K), paratype male (I, J): A Female left chela (lateral view); B Left chela (dorsal view); C Left chelicera (dorsal view); D Coxal area and manducatory process (ventral view); E Carapace (dorsal view); F Leg Ⅳ (lateral view); G Leg Ⅰ (lateral view); H Left pedipalp (minus chela, dorsal view); I Male left chelicera (dorsal view); J Male genital area (ventral view); K Female genital area (ventral view). Scale bars: 0.20 mm (A, B, D, H); 0.10 mm (C, E–G, I–K).

Figure 3. — *Lechytiaacutidentata* sp. nov., holotype female: A Carapace (dorsal view); B Left chelicera (dorsal view), with details of teeth; C Chaetotaxy of genital area (sternites II–III) (male); D Rallum; E Left pedipalp (minus chela, dorsal view). Scale bars: 0.10 mm (A–C); 0.05 mm (D); 0.20 mm (E).

Figure 4. — *Lechytiaacutidentata* sp. nov., holotype female (A–D), paratype male (E, F): A Left chela (lateral view), with details of teeth and trichobothrial pattern; B Left chela (dorsal view); C Leg I (lateral view); D Leg IV (lateral view); E Left chela (lateral view), with details of teeth and trichobothrial pattern; F Left chelicera (dorsal view), with details of teeth. Scale bars: 0.20 mm (A, B, E); 0.10 mm (C, D, F).

Cephalothorax (Fig. 2D, E and Fig. 3A): carapace nearly subquadrate, 0.98–1.09 times longer than broad; anterior margin denticulate; without epistome; two small corneate eyes; with 18 setae arranged 6: 4: 4: 2: 2, most setae heavy, long and gently curved; with four pairs of lyrifissures, first pair situated antero-medially, the second pair situated interno-underneath to the eyes, the third pair situated slightly interior to the sole pair of setae of the intermediate row and the fourth pair situated exterior to the sole pair of setae of the posterior row. Manducatory process with two acuminate distal setae, about equal in length, the distal setae terminally acuminate (Fig. 5C); apex of coxa I with a triangular apical projection (Fig. 5D); coxal spines and intercoxal tubercle absent. Chaetotaxy of coxae: P 5, Ⅰ 7, II 7, III 7, IV 7.

Figure 5. — *Lechytiaacutidentata* sp. nov., paratype female: A Rallum; B Serrula exterior; C Manducatory process (ventral view); D Coxal area (ventral view); E Right chela (lateral view), with details of teeth and trichobothrial pattern; F Chelal basal details of teeth and trichobothrial.

Chelicera (Fig. 2C and Fig. 3B): 1.39–1.56 times longer than broad; five setae present on hand, all setae acuminate, ventrobasal setae shorter than others; movable finger with one medial seta. Cheliceral palm has moderate wrinkles on both ventral and dorsal sides. Fixed finger with one large tooth and two roughened ridges proximally; movable finger with an acute apical tooth and four pointed, conspicuous middle teeth; galea shaped like a tooth (♂♀) (Fig. 2C, I, Fig. 3B and Fig. 4F). Serrula exterior with 17–18 blades, smooth surface and side creases (Fig. 5B). Rallum with eight blades, subdistal blade strongly recumbent, others in straight row (Fig. 3D and Fig. 5A).

Pedipalp (Fig. 2A, B, H, Fig. 3E, Fig. 4A and B): trochanter 1.54–1.91, femur 3.86–4.73, patella 1.76–1.88, chela 3.59–3.90, hand 1.54–1.75 times longer than broad; femur 1.73–1.80 times longer than patella; movable chelal finger 1.28–1.42 times longer than hand and 0.57–0.61 times longer than chela. Setae generally long and acuminate. Fixed chelal finger and hand with eight trichobothria, ib, isb, eb and esb on dorsum of hand, ib and isb basally, esb submedially, eb closer to ib and isb than to esb; ist situated basally on fixed finger, est and it situated submedially and medially on fixed finger, et and dx distally; movable chelal finger with four trichobothria, b closer to sb than to t, sb closer b than to st; b and sb situated more than one diameter apart (Fig. 2A, Fig. 4A, Fig. 5E and F); sensilla absent. Both chelal fingers with a row of teeth: fixed finger with 50–52 developed retrorse, pointed teeth; movable finger with 48–53 upright, pointed teeth.

Opisthosoma: tergites and sternites undivided; setae acuminate. Tergal chaetotaxy I–Ⅻ: 6: 4–6: 5–6: 6–7: 6: 6: 6: 6: 6: 4–6: T2T: 0. Sternal chaetotaxy Ⅳ–Ⅻ: 14–16: 12: 10: 10–12: 8–10: 8: 5–6: -: 2. Genital area weakly sclerotised with U-shaped frame (Fig. 2K).

Legs (Fig. 2F, G, Fig. 4C and D): leg Ⅰ: femur 1.56–1.93 times longer than patella; tarsus 1.61–1.76 times longer than tibia. Leg Ⅳ: femoropatella 2.10–2.50 times longer than deep; tibia 3.78–4.25 times longer than deep; with sub-basal tactile setae on basitarsal segments. Arolium slightly shorter than the claws, not divided; claws simple.

Adult male (paratype) (Fig. 1A, Fig. 2J, Fig. 3C, Fig. 4E and F). Mostly same as females, but a little smaller on average; tergal chaetotaxy Ⅰ–Ⅻ: 6: 6: 6: 6: 6: 6: 6: 6: 6: 4: T2T: 0; sternal chaetotaxy Ⅳ–Ⅻ: 14: 10: 8: 8: 8: 8: 6: -: 2. Genital region: partial setaes bifurcate.

Dimensions (length/breadth or, in the case of the legs, length/depth in mm; ratios in parentheses). Male: body length 1.71. Pedipalps: trochanter 0.21/0.11 (1.91), femur 0.49/0.12 (4.08), patella 0.29/0.17 (1.71), chela 0.75/0.19 (3.95), hand 0.32/0.19 (1.68), movable chelal finger length 0.44. Chelicera 0.24/0.16 (1.50), movable finger length 0.12. Carapace 0.45/0.39 (1.15). Leg I: trochanter 0.18/0.11 (1.64), femur 0.29/0.06 (4.83), patella 0.13/0.05 (2.60), tibia 0.12/0.05 (2.40), tarsus 0.25/0.04 (6.25). Leg Ⅳ: trochanter 0.16/0.09 (1.78), femoropatella 0.37/0.18 (2.06), tibia 0.33/0.09 (3.67), basitarsus 0.16/0.06 (2.67), telotarsus 0.22/0.04 (5.50).

Females: body length 1.79–2.07. Pedipalps: trochanter 0.20–0.21/0.11–0.13 (1.54–1.91), femur 0.51–0.54/0.11–0.14 (3.86–4.73), patella 0.29–0.30/0.16–0.17(1.76–1.88), chela 0.77–0.82/0.20–0.22 (3.59–3.90), hand 0.32–0.37/0.20–0.22 (1.54–1.75), movable chelal finger length 0.45–0.48. Chelicera 0.25–0.29/0.18–0.20 (1.39–1.56), movable finger length 0.15–0.16. Carapace 0.43–0.47/0.42–0.46 (0.98–1.09). Leg I: trochanter 0.11–0.14/0.08–0.11 (1.18–1.75), femur 0.25–0.29/0.06–0.07 (3.71–4.83), patella 0.15–0.16/0.05–0.07 (2.14–3.00), tibia 0.12–0.17/0.05 (3.20–3.60), tarsus 0.27–0.30/0.04–0.05 (5.60–7.50). Leg Ⅳ: trochanter 0.15–0.19/0.09–0.14 (1.25–1.78), femoropatella 0.42–0.45/0.18–0.20 (2.10–2.50), tibia 0.33–0.35/0.08–0.09 (3.78–4.25), basitarsus 0.16–0.18/0.06–0.07 (2.29–2.83), telotarsus 0.23–0.24/0.04–0.05 (4.60–6.00).

Diagnosis

The new species belongs to the hoffi species-group and is characterised by the following combination of characteristics: trichobothria b and sb situated more than one areolar diameter apart; movable chelal finger with upright and point teeth; palpal chela 3.59–3.90 (♀), 3.95 (♂) and palpal hand 1.54–1.75 (♀), 1.68 (♂) longer than broad; palpal femur 0.51–0.54 mm (♀), 0.49 mm (♂), palpal hand 0.33–0.37 mm (♀), 0.32 mm (♂) and chelal movable finger 0.45–0.48 mm (♀), 0.44 mm (♂) long.

Lechytiaacutidentata sp. nov. most resembles L.yulongensis due to trichobothria b and sb on movable chelal finger situated more than one areolar diameter apart. However, the new species differs from L.yulongensis in the pattern of teeth of fixed chelal finger with upright and point teeth in L.acutidentata sp. nov., but retrorse and point teeth in L.yulongensis (Zhang and Zhang 2014).

Etymology

The specific name is derived from a combination of the Latin words “acutus” and “dentatus”, meaning pointed and toothed, respectively, which refers to the pointed teeth on the movable chelal fingers.

Distribution

China (Xizang Autonomous Region).

Ecology

All specimens were collected under bark in denser forests (Fig. 6).

Figure 6. — Type locality of *Lechytiaacutidentata* sp. nov. A Numerous *L.acutidentata* sp. nov. and silk nests; B A living of *L.acutidentata* sp. nov. in its natural environment; C Silk nests of *L.acutidentata* sp. nov.; **D–F**. The habitat where *L.acutidentata* sp. nov. specimens were collected.

Biology

Their rounded nests are built by thin silks and had a thicker centre (Fig. 6A and C). Some silk nests are close together, but independent from each other (Fig. 6A).

Notes

Generally, the holotypes of Lechytia species are male specimens. Here, we chose a female specimen as the holotype of L.acutidentata, because the sole male specimen has a rather transparent and brittle body. It was probably caught and soaked in alcohol straight after just moulting.