Lagynochthonius xiaoensis Hou, Feng & Zhang, 2023

Lagynochthonius xiaoensis Hou, Feng & Zhang, 2023

Chinese name. ẘǟȗ伪Dz

Figs 45–49 View FIGURE 45 View FIGURE 46 View FIGURE 47 View FIGURE 48 View FIGURE 49

Lagynochthonius xiaoensis Hou, Feng & Zhang, 2023a: 51–55 View Cited Treatment , figs 40–43.

Material examined. ♀ (Ps.- MHBU-GZC190727- 01-01 ) (holotype) GoogleMaps , 1 ♀ (Ps. - MSWU-GZC190727-01- 02 ) (paratypes): China, Guizhou Province, Suiyang County, Yangchuan Sub-district, Xinglong Village, Xiao Cave , under stones in the deep zone [27.999336°N, 107.175514°E], 976 m a.s.l., 27 July 2019, Zegang Feng, Zhaoyi Li & Chen Zhang leg GoogleMaps ; 1 ♂ (Ps.- MHBU-GZ2024012601 ) , 2 ♀ (Ps. - MHBU-GZ2024012602–03 ): China, Guizhou Province, Zunyi City, Suiyang County, Xiao Cave 2 [27.99897978°N, 107.17482272°E], 948 m a.s.l., 26 January 2024, Jiaqi Zhao, Yitin Xu & Jianzhou Sun leg. GoogleMaps

Revised diagnosis. (♂ ♀). Small sized hypogean species; carapace without eyes or eyespots, anterior margin smooth and epistome obtuse and small, round; tergites Ⅰ– Ⅰ V each with four setae. Pedipalps slender, chela 6.20 (♂), 6.00–6.85 (♀) times as long as broad; femur 6.00 (♂), 5.73–6.00 (♀) times as long as broad; both chelal fingers without intercalary teeth and a modified accessory tooth (td) on prolateral-retrolateral face; chemosensory setae (sc) present on dorsum of chelal hand.

Description. Adult male ( Figs 45A View FIGURE 45 , 46A–F View FIGURE 46 , 47 View FIGURE 47 , 48 View FIGURE 48 ).

Color generally pale yellow, chelicerae, carapace, pedipalps and tergites slightly darker black, soft parts pale.

Cephalothorax ( Figs 46D View FIGURE 46 , 47A View FIGURE 47 ): carapace nearly subquadrate, 0.98 times as long as broad, weakly constricted basally; posterior region with squamous sculpturing laterally, other area smooth, without furrows; anterior margin smooth, without serrations; epistome obtuse and small, round, without eyes or eyespots; with 18 setae arranged s4s: 4: 4: 2: 2, most setae heavy, long and gently curved, anterolateral setae much shorter than others; with three pairs of lyrifissures, first and second pair situated middle and flank to the setae of ocular row, third pair situated lateral to the sole pair of setae of posterior row. Manducatory process with two acuminate distal setae, anterior seta more than 1/2 length of medial seta; apex of coxa I with a rounded anteromedial process; coxae II with 8–9 terminally indented coxal spines on each side, set as an oblique and arc row, central spines slightly longer than the others ( Fig. 47D View FIGURE 47 ); intercoxal tubercle absent; chaetotaxy of coxae: P 3, I 3, II 4, III 5, IV 5.

Chelicera ( Figs46C View FIGURE 46 , 47B View FIGURE 47 ): almost as long as carapace, 1.85 times as long as broad; five setae and two lyrifissures (exterior condylar lyrifissure and exterior lyrifissure) present on hand, all setae acuminate, ventrobasal setae shorter than others; movable finger with one medial seta. Cheliceral hand with moderate wrinkle on both ventral and dorsal sides. Both fingers well provided with teeth, fixed finger with 11 teeth, distal one largest; movable finger with 10 retrorse contiguous small teeth; galea completely vestigial ( Fig. 47B View FIGURE 47 ). Serrula exterior with 19 and serrula interior with 13 blades. Rallum with eight 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. 47C View FIGURE 47 ).

Pedipalp ( Figs 46A–B, 46E View FIGURE 46 , 47E View FIGURE 47 , 48A–B View FIGURE 48 ): trochanter 2.00,femur6.00,patella2.18,chela6.20,hand 2.33times as long as broad; femur 2.75 times as long as patella; movable chelal finger 1.66 times as long as hand and 0.62 times as long as chela. Setae generally long and acuminate. Chelal hand gradually constricted towards fingers, apodeme complex of movable chelal finger strongly sclerotized. 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 at base of fixed chelal finger; esb slightly distal eb and ist slightly distal to esb; it slightly distal to est, situated subdistally; et slightly near to tip of fixed chelal finger, slightly close to chelal teeth; dx situated distal to et; sb situated midway between st and b; b and t situated subdistally, t situated at the same level as it and distal to b; est situated distal to b and close to it ( Figs. 46A View FIGURE 46 , 48A View FIGURE 48 ). Microsetae (chemosensory setae) present on dorsum of chelal hand ( Figs. 46B View FIGURE 46 , 48B View FIGURE 48 ). Both chelal fingers with a row of teeth, spaced regularly along the margin, teeth smaller distally and proximally: fixed finger with 27 well-spaced, pointed teeth, and a modified accessory tooth on prolateral-retrolateral face (td, slightly distal to dx); movable finger with 10 well-spaced, pointed teeth, plus 15 vestigial, rounded and contiguous basal teeth.

Opisthosoma: generally typical, pleural membrane finely granulated. All tergites and sternites undivided; setae uniseriate and acuminate. Tergal chaetotaxy I–XII: 4: 4: 4: 4: 4: 4: 5: 5: 6: 4: T2T: 0. Sternal chaetotaxy IV– XII: 14: 10: 10: 9: 9: 11: 8: -: 2. Genital region: sternite II with 10 setae scattered on median area, genital opening slit-like, sternite III with 30 setae ( Fig. 46F View FIGURE 46 ).

Legs ( Fig. 48C–D View FIGURE 48 ): fine granulation present on anterodorsal faces of femur IV and patella IV. Leg Ⅰ: femur 1.89 times as long as patella; tarsus 2.11 times as long as tibia. Leg IV: femoropatella 3.38 times as long as deep; tibia 4.71times as long as deep; with basal tactile setae on both tarsal segments: basitarsus 3.20 times as long as deep (TS = 0.44), telotarsus 9.75 times as long as deep and 2.44 times as long as basitarsus (TS = 0.31). Setae of leg I (trochanter to tibia) 3: 10: 8: 12, setae of leg IV (trochanter to basitarsus) 2: 3: 6: 9: 9. Arolium not divided, slightly shorter than the simple claws.

Adult females ( Figs 45B View FIGURE 45 , 46G View FIGURE 46 ). Mostly same as male; tergal chaetotaxy Ⅰ–ⅩII: 4: 4: 4: 4: 4–5: 4: 4: 5: 5: 5–6: T2T: 0; sternal chaetotaxy IV–ⅩII: 8–10: 9–10: 9: 9: 8–9: 10–11: 8–11: -: 2. Genital region: sternite II with 10 setae scattered on median area, sternite III with a row of eight setae.

Dimensions (length/breadth or, in the case of the legs, length/depth in mm; ratios in parentheses). Male: body length 1.57. Pedipalps: trochanter 0.20/0.10 (2.00), femur 0.66/0.11 (6.00), patella 0.24/0.11 (2.18), chela 0.93/0.15 (6.20), hand 0.35/0.15 (2.33), movable chelal finger length 0.58. Chelicera 0.37/0.20 (1.85), movable finger length 0.22. Carapace 0.40/0.41 (0.98). Leg I: trochanter 0.12/0.08 (1.50), femur 0.34/0.06 (5.67), patella 0.18/0.04 (4.50), tibia 0.18/0.04 (4.50), tarsus 0.38/0.04 (9.50). Leg IV: trochanter 0.17/0.12 (1.42), femoropatella 0.54/0.16 (3.38), tibia 0.33/0.07 (4.71), basitarsus 0.16/0.05 (3.20), telotarsus 0.39/0.04 (9.75).

Females: body length 1.31–1.39. Pedipalps: trochanter 0.19/0.11 (1.73), femur 0.63–0.66/0.11 (5.73– 6.00), patella 0.19–0.26/0.12 (1.58–2.17), chela 0.89– 0.96/0.13–0.16 (5.94), hand 0.35–0.36/0.13–0.16 (2.25– 2.69), movable chelal finger length 0.55–0.60. Chelicera 0.36–0.38/0.20–0.21 (1.80–1.81), movable finger length 0.22–0.23. Carapace 0.39–0.41/0.42 (0.93–0.97). Leg I: trochanter 0.11–0.12/0.07–0.09 (1.33–1.57), femur 0.33– 0.36/0.05–0.06 (5.50–7.20), patella 0.18/0.05 (3.60), tibia 0.16–0.17/0.04 (4.00–4.25), tarsus 0.34–0.36/0.04 (8.50–9.00). Leg IV: trochanter 0.14–0.16/0.09–0.11 (1.45–1.56), femoropatella 0.49–0.53/0.16–0.17 (3.06– 3.12), tibia 0.34/0.07 (4.86), basitarsus 0.16–0.17/0.06 (2.67–2.83), telotarsus 0.36–0.38/0.04 (9.00–9.50).

Remarks. Lagynochthonius xiaoensis was described from two female specimens by Hou, Feng & Zhang (2023). In a recent collection trip, some new specimens were collected at the type locality (Pianxiao Cave in Zunyi City, Guizhou Province, China), including one male and two females, which conform to the diagnostic characteristics of L. xiaoensis . We provide a revised diagnosis of L. xiaoensis in this study based on the holotype and the recently collected specimens.

Lagynochthonius xiaoensis most closely resembles L. minimus in the absence of intercalary teeth, the presence of four setae on tergites I–IV, the small, obtuse, and rounded epistome, and the absence of eyes or eyespots on the carapace, but differs in following combination of characters: trichobothrium sb situated midway between st and b, and fixed chelal finger with 27 (♂), 24–25 (♀) teeth (vs. trichobothrium sb closer to st than to b, and fixed chelal finger with 34–36 (♂), 35–37 (♀) teeth in L. minimus ) ( Hou et al. 2022b).

Ecology. All specimens were collected under rocks inside the cave.

Distribution. Known only from the type locality ( China, Guizhou Province).