New cave-dwelling pseudoscorpions of the genus Lagynochthonius (Pseudoscorpiones, Chthoniidae) from Guizhou in China Author Hou, Yanmeng 0000-0003-0059-3419 Author Feng, Zegang 0000-0002-5809-5984 Author Zhang, Feng 0000-0002-3347-1031 text Zootaxa 2023 2023-06-27 5309 1 1 64 http://dx.doi.org/10.11646/zootaxa.5309.1.1 journal article 55245 10.11646/zootaxa.5309.1.1 048abd7b-8c78-494e-b466-b614aeef7f6b 1175-5326 8090046 C930242A-041C-4CEC-8B2F-2DB671A2395D Lagynochthonius biyunensis sp. nov. (ỠỄṄṁae) Figs 2–5 Type material. Holotype ♂ (Ps.- MHBU-GZC190805-01 ): China , Guizhou Province , Panzhou City , Chengguan Town , Nanmen Village , Biyun Park , Biyun Cave , under the detritus and on the walls in the deep zone [ 25°46′18.91″N , 104°38′24.0″E ], 1496 m a.s.l. , 5 August 2019 , Zegang Feng , Zhaoyi Li & Chen Zhang leg. Paratypes : 4 ♂ (Ps.- MHBU-HBUARA#2022-498 - 01 –HBUARA#2022-498-04), 2 ♀ (Ps.- MSWU-HBUARA#2022-498 - 05 & HBUARA#2022-498-06), with the same location as the holotype, 2 August 2022 , Yanmeng Hou , Lu Zhang , Jianzhou Sun & Wenlong Fan leg. Etymology. Named after the type locality, Biyun Cave. Diagnosis (♂ ♀ ). Moderately sized troglomorphic species with elongated appendages; carapace without eyes or eyespots; anterior margin of carapace thin, finely denticulated, epistome small, pointed, triangular; posterior margin of carapace with two setae; tergites Ⅰ– Ⅴ each with four setae. Pedipalps slender, femur 8.06 (♂), 7.82–7.89 ( ♀ ) times longer than broad; chela 6.85–7.08 (♂), 7.27–7.43 ( ♀ ) times longer than broad; chelal fingers without intercalary teeth; chemosensory setae ( sc ) present on dorsum of chelal hand . Description. Males ( holotype and paratypes ) ( Figs 2F , 3A , 4A–F , 5 ). Colour: generally pale yellow, chelicerae, pedipalps and tergites slightly darker, soft parts pale. Cephalothorax ( Figs 4C , 5A ): carapace 1.00 times longer than broad, gently narrowed posteriorly; surface smooth, without furrows; no traces of eyes; anterior margin slightly serrate; epistome pointed and small, triangular; with 18 setae arranged s4s: 4: 4: 2: 2, most setae heavy, long and gently curved, anterolateral setae much shorter than others; with two pairs of lyrifissures, first pair situated middle to setae of ocular row, second pair situated lateral to the sole pair of setae of posterior row. Chaetotaxy of coxae: P 3, Ⅰ 3, II 4, III 5, IV 5; manducatory process with two acuminate distal setae, anterior seta less than 1/2 length of medial seta; apex of coxa Ⅰ with small, rounded anteromedial process; coxae II with ten terminally indented coxal spines on each side, set as an oblique row, longer spines present in the middle of the row, becoming shorter distally and proximally and incised for about half their length ( Fig. 5C ); intercoxal tubercle absent; without sub-oral seta. FIGURE 2. Biyun Cave, type locality of Lagynochthonius biyunensis sp. nov. , A. Entrance; B. Inside the cave entrance; C. Another entrance penetrated by a river; D. A narrow tunnel to the interior of the cave; E. Area where L. biyunensis sp. nov. specimens were collected (red arrows); F. Live male of L. biyunensis sp. nov. in its natural environment. FIGURE 3. Lagynochthonius biyunensis sp. nov. , A. Holotype male, habitus (dorsal view); B. Paratype female, habitus (dorsal view). Chelicera ( Figs 4D , 5B ): large, about as long as carapace, 2.40–2.47 times longer than broad; five setae and two lyrifissures (exterior condylar lyrifissure and exterior lyrifissure) present on hand, all setae acuminate, ventrobasal seta shorter than others; movable finger with one medial seta. Cheliceral palm with moderate hispid granulation on both ventral and dorsal sides. Both fingers well provided with teeth, fixed finger with 15–17 teeth, distal one largest; movable finger with 21–22 retrorse contiguous small teeth; galea absent ( Fig. 5B ). Serrula exterior with 22–23 blades and serrula interior with 14–15 blades. Rallum with nine blades, the distal one longest and recumbent basally, with fine barbules and slightly set apart from the other blades, latter tightly grouped and with long pinnae, some of which are subdivided ( Fig. 5D ). Pedipalp ( Figs 4A–B, E , 5E–G ): long and slender, trochanter 1.20–1.26, femur 8.06, patella 2.35, chela 6.85– 7.08, hand 2.70–2.81 times longer than broad; femur 2.74 times longer than patella; movable chelal finger 1.49–1.52 times longer than hand and 0.59–0.60 times longer than chela. Setae generally long and acuminate; one distal lyrifissure present on patella ( Figs 4E , 5E ). Chelal palm gradually constricted towards fingers, apodeme complex of movable chelal finger strongly sclerotized, with weak granulation dorsally at base of fixed chelal finger and hand. Fixed chelal finger and hand with eight trichobothria, movable chelal finger with four trichobothria, ib and isb situated close together, submedially on dorsum of chelal hand; eb , esb and ist forming a straight oblique row at base of fixed chelal finger; it slightly distal to est , situated subdistally; et slightly near to tip of fixed chelal finger, very close to chelal teeth; dx situated distal to et ; sb situated midway between b and st ; b and t situated subdistally, t situated distal to it ; est situated distal to b ( Fig. 5F ). A tiny retrolateral lyrifissure present at base of fixed chelal finger (situated distal to ist ). Both chelal fingers with a row of teeth, homodentate, spaced regularly along the margin, larger and well-spaced teeth present in the middle of the row, becoming smaller and closer distally and proximally: fixed chelal finger with 29–30 macrodenticles, slightly retrorse and pointed; movable chelal finger with 27–29 macrodenticles (slightly smaller than teeth on fixed chelal finger), slightly retrorse and pointed ( Fig. 5F ). Chelal fingers slightly curved in dorsal view; microsetae (chemosensory setae) present on dorsum of chelal hand ( Figs 4B , 5G ). Opisthosoma: generally typical, pleural membrane finely granulated. Tergites and sternites undivided; setae uniseriate and acuminate. Tergal chaetotaxy Ⅰ–XII: 4: 4: 4: 4: 4: 4–5: 4: 4–5: 4–5: 4: T2T: 0, tergites VIII–IX each with an unpaired median seta. Sternal chaetotaxy III–XII: 13–14: 12–14: 9: 9: 8–9: 9: 9: 9: 0: 2. Anterior genital operculum with ten setae, genital opening slit-like, with 11–13 marginal setae on each side, 34 in total ( Fig. 4F ). FIGURE 4. Lagynochthonius biyunensis sp. nov. , holotype male (A–F), paratype female (G): A. Left chela (lateral view); B. Left chela (dorsal view); C. Carapace (dorsal view); D. Left chelicera (dorsal view); E. Left pedipalp (minus chela, dorsal view); F. Male genital area (ventral view); G. Female genital area (ventral view). FIGURE 5. Lagynochthonius biyunensis sp. nov. , holotype male: A. Carapace (dorsal view); B. Left chelicera (dorsal view), with details of teeth; C. Coxal spines on coxae II (ventral view); D. Rallum; E. Left pedipalp (minus chela, dorsal view); F. Left chela (lateral view), with details of teeth and trichobothrial pattern; G. Left chela (dorsal view); H. Leg Ⅰ (lateral view); I. Leg IV (lateral view). Scale bars: 0.20 mm (A–B, E–I); 0.10 mm (C–D). Legs ( Fig. 5H–I ): generally typical, long and slender. Fine granulation present on anterodorsal faces of trochanter IV, femur Ⅰ, IV and patella IV. Femur of leg Ⅰ 1.79–1.86 times longer than patella and with one lyrifissure at the base of femur; tarsus 2.38–2.47 times longer than tibia. Femoropatella of leg IV 4.33–4.38 times longer than deep; tibia 6.55–6.64 times longer than deep; with basal tactile setae on both tarsal segments: metatarsus 3.78–4.00 times longer than deep (TS = 0.32–0.34), tarsus 14.50–14.83 times longer than deep and 2.62–2.72 times longer than metatarsus (TS = 0.27–0.33). Arolium slightly shorter than the claws, not divided; claws simple. Adult females ( paratypes ) ( Figs 3B , 4G ). Mostly same as males, but a little larger; chaetotaxy of coxae: P 3, Ⅰ 3, II 3–4, III 5, IV 5; tergal chaetotaxy Ⅰ–XII: 4: 4: 4: 4: 4: 4: 4: 4: 4: 4: T2T: 0; sternal chaetotaxy IV–XII: 12–13: 10: 9: 9: 9: 9: 9: 0: 2; anterior genital operculum with ten setae, posterior margin with 12–14 marginal setae, 22–24 in total; leg IV with a long tactile seta on both tarsal segments: metatarsus 4.00–4.63 times longer than deep (TS = 0.32– 0.34), tarsus 14.17–16.17 times longer than deep and 2.62–2.66 times longer than metatarsus (TS = 0.22–0.28). Dimensions (length/breadth or, in the case of the legs, length/depth in mm; ratios in parentheses). Males: body length 2.02–2.10. Pedipalps: trochanter 0.24/0.19–0.20 (1.20–1.26), femur 1.29/0.16 (8.06), patella 0.47/0.20 (2.35), chela 1.84–1.85/0.26–0.27 (6.85–7.08), hand 0.73/0.26–0.27 (2.70–2.81), movable chelal finger length 1.09–1.11. Chelicera 0.72–0.74/0.30 (2.40–2.47), movable finger length 0.39–0.40. Carapace 0.60/0.60 (1.00). Leg Ⅰ: trochanter 0.19/0.16 (1.19), femur 0.69–0.70/0.09 (7.67–7.78), patella 0.37–0.39/0.08 (4.63–4.88), tibia 0.32/0.06 (5.33), tarsus 0.76–0.79/0.05–0.06 (13.17–15.20). Leg IV: trochanter 0.27–0.29/0.16 (1.69–1.81), femoropatella 1.04–1.05/0.24 (4.33–4.38), tibia 0.72–0.73/0.11 (6.55–6.64), metatarsus 0.32–0.34/0.08–0.09 (3.78–4.00), tarsus 0.87–0.89/0.06 (14.50–14.83). Females: body length 2.19–2.27. Pedipalps: trochanter 0.24–0.27/0.20–0.21 (1.20–1.29), femur 1.33– 1.42/0.17–0.18 (7.82–7.89), patella 0.46–0.51/0.20–0.22 (2.30–2.32), chela 1.89–2.08/0.26–0.28 (7.27–7.43), hand 0.75–0.82/0.26–0.28 (2.88–2.93), movable chelal finger length 1.13–1.24. Chelicera 0.76–0.83/0.33–0.34 (2.30– 2.44), movable finger length 0.41–0.45. Carapace 0.64/0.64–0.72 (0.89–1.00). Leg Ⅰ: trochanter 0.18–0.19/0.16 (1.13–1.19), femur 0.69–0.80/0.09 (7.67–8.89), patella 0.39–0.43/0.08 (4.88–5.38), tibia 0.32–0.36/0.06–0.07 (5.14–5.33), tarsus 0.79–0.86/0.06 (13.17–14.33). Leg IV: trochanter 0.28–0.30/0.16 (1.75–1.88), femoropatella 1.03–1.11/0.23–0.24 (4.48–4.63), tibia 0.69–0.75/0.11–0.12 (6.25–6.27), metatarsus 0.32–0.37/0.08 (4.00–4.63), tarsus 0.85–0.97/0.06 (14.17–16.17). Distribution. Known only from the type locality.