Lagynochthonius guanniuensis Hou, Feng & Zhang, 2023

SUN, JIANZHOU, GUO, XIANGBO & ZHANG, FENG, 2024, A review of the genus Lagynochthonius Beier, 1951 (Pseudoscorpiones, Chthoniidae) from China, Megataxa 12 (2), pp. 177-250 : 204-210

Lagynochthonius guanniuensis Hou, Feng & Zhang, 2023

Chinese name. Ŕ+ȗ伪Dz

Figs 22–26

Lagynochthonius guanniuensis Hou, Feng & Zhang, 2023a: 11–16 , figs 6–9.

Material examined. ♀ (Ps.- MHBU-GZXF-20-02-01 ) (holotype) , 1 ♀ (Ps.- MSWU-GZXF-20-02-02 ) (paratype): China, Guizhou Province, Xifeng County, Wenquan Town, Wenquan Village, Guanniu Cave , under the detritus in the deep zone [27.223333°N, 106.871667°E], 853 m a.s.l., 15 August 2020, Zegang Feng, Hongru Xu & Yanmeng Hou leg ; 10 ♂ (Ps.- MHBU-GZ2024012501–10 ) , 6 ♀ (Ps.- MHBU-GZ2024012511–16 ): China, Guizhou Province, Guiyang City, Xifeng County, Wenquan Town, Guanniu Cave 1 [27.22384538°N, 106.86832882°E], 849 m a.s.l., 25 January 2024, Jiaqi Zhao, Yitin Xu & Jianzhou Sun leg.

Revised diagnosis. (♂ ♀). Moderately sized hypogean species; carapace without eyes or eyespots, anterior margin smooth and epistome small and pointed, triangular; tergites Ⅰ–IV each with two setae. Pedipalps slender, chela 7.31–7.83 (♂), 6.70–7.33 (♀) times as long as broad; femur 7.94–8.69 (♂), 7.83–7.56 (♀) times as long as broad; both chelal fingers with intercalary teeth and a modified accessory tooth (td) on prolateral-retrolateral face; chemosensory setae (sc) present on dorsum of chelal hand.

Description. Adult males ( Figs 22A, 23A–F, 24, 25).

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

Cephalothorax ( Figs 23D, 24A): carapace nearly subquadrate, 0.97–1.00 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 small and point; 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 less than 1/2 length of medial seta; apex of coxa I with a rounded anteromedial process; coxae II with 9–10 terminally indented coxal spines on each side, set as an oblique and arc row, central spines slightly longer than the others ( Fig. 24D); intercoxal tubercle absent; chaetotaxy of coxae: P 3, I 3, II 4, III 5, IV 5.

Chelicera ( Figs 23C, 24B): almost as long as carapace, 1.91–2.06 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 17–19 teeth, distal one largest; movable finger with 13–15 retrorse contiguous small teeth; galea completely vestigial ( Fig. 24B). Serrula exterior with 17–24 and serrula interior with 12–15 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. 24C).

Pedipalp ( Figs 23A–B, 23E, 24E, 25A–B): trochanter 1.89, femur 7.94–8.69 patella 2.55–2.70, chela 7.31–7.83, hand 2.81–3.08 times as long as broad; femur 2.41–2.57 times as long as patella; movable chelal finger 1.55–1.67 times as long as hand and 0.61–0.63 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 b and st; b and t situated subdistally, t situated at the same level as it and distal to b; est situated distal to b ( Figs. 23A, 25A). Microsetae (chemosensory setae) present on dorsum of chelal hand ( Figs. 23B, 25B). Both chelal fingers with a row of teeth, heterodentate, spaced regularly along the margin, teeth smaller distally and proximally: fixed finger with 31–36 well-spaced, pointed teeth, plus 27– 31 intercalary microdenticles, and a modified accessory tooth on prolateral-retrolateral face (td, slightly distal to dx); movable finger with 30–33 well-spaced, pointed teeth, plus 4–6 vestigial, rounded and contiguous basal teeth and 24– 27 intercalary microdenticles.

Opisthosoma: generally typical, pleural membrane finely granulated. All tergites and sternites undivided; setae uniseriate and acuminate. Tergal chaetotaxy I–XII: 2: 2: 2: 2–3: 4: 4: 4: 4: 5: 2: T2T: 0. Sternal chaetotaxy ⅠV–XII: 12: 8–10: 7–8: 6–7: 7: 7: 7: -: 2. Genital region: sternite II with 9–11 setae scattered on median area, genital opening slit-like, sternite III with 18–20 setae ( Fig. 23F).

Legs ( Fig. 25C–D): fine granulation present on anterodorsal faces of femur IV and patella IV. Leg Ⅰ: femur 1.77–2.00 times as long as patella; tarsus 2.36–2.44 times as long as tibia. Leg IV: femoropatella 4.62–5.76 times as long as deep; tibia 6.91–7.60 times as long as deep; with basal tactile setae on both tarsal segments: basitarsus 4.63–4.75 times as long as deep (TS = 0.26– 0.38), telotarsus 16.00–16.67 times as long as deep and 2.55–2.70 times as long as basitarsus (TS = 0.20–0.30). Setae of leg I (trochanter to tibia) 3: 6–9: 6–7: 5–9, setae of leg IV (trochanter to basitarsus) 1–3: 3: 6: 8–10: 6– 9. Arolium not divided, slightly shorter than the simple claws.

Adult females ( Figs 22B, 23G). Mostly same as males; tergal chaetotaxy Ⅰ–ⅩII: 2: 2: 2: 2: 4: 4: 4: 4: 5: 2: T2T: 0; sternal chaetotaxy IV–ⅩII: 8–12: 7–9: 8: 7: 7–8: 7–8: 7–8: -: 2. Genital region: sternite II with 9–10 setae scattered on median area, sternite III with a row of 8–12 setae.

Dimensions (length/breadth or, in the case of the legs, length/depth in mm; ratios in parentheses). Males: body length 2.07–2.24. Pedipalps: trochanter 0.34–0.36/0.18–0.19 (1.89), femur 1.35–1.39/0.16–0.17 (7.94–8.69), patella 0.54–0.56/0.20–0.22 (2.55–2.70), chela 1.88–1.99/0.24–0.26 (7.31–7.83), hand 0.73– 0.75/0.24–0.26 (2.81–3.08), movable chelal finger length 1.15–1.25. Chelicera 0.65–0.66/0.32–0.34 (1.91–2.06), movable finger length 0.38. Carapace 0.62–0.65/0.62– 0.65 (0.97–1.00). Leg I: trochanter 0.22–0.23/0.12–0.14 (1.57–1.77), femur 0.78–0.86/0.08–0.09 (8.67–9.56), patella 0.43–0.45/0.07–0.09 (4.78–6.43), tibia 0.34– 0.36/0.07–0.08 (4.38–5.14), tarsus 0.83–0.88/0.06–0.07 (12.14–14.67). Leg IV: trochanter 0.28–0.32/0.17–0.19 (1.56–1.71), femoropatella 1.20–1.21/0.21–0.26 (4.62– 5.76), tibia 0.76–0.79/0.10–0.11 (6.91–7.60), basitarsus 0.37–0.38/0.08 (4.63–4.75), telotarsus 0.96–1.00/0.06 (16.00–16.67).

Females: body length 2.08–2.69. Pedipalps: trochanter 0.36–0.37/0.18–0.21 (1.76–2.06), femur 1.36– 1.41/0.18–0.21 (7.83–8.56), patella 0.54–0.58/0.21–0.22 (2.45–2.71), chela 1.89–2.01/0.27–0.30 (6.70–7.33), hand 0.73–0.76/0.27–0.30 (2.53–2.61), movable chelal finger length 1.16–1.24. Chelicera 0.71–0.75/0.35–0.39 (1.87–2.02), movable finger length 0.38–0.42. Carapace 0.66–0.69/0.63–0.68 (0.98–1.09). Leg I: trochanter 0.23–0.24/0.12–0.17 (1.35–2.00), femur 0.72–0.85/0.08– 0.09 (9.00–10.62), patella 0.39–0.45/0.08–0.10 (1.85– 1.98), tibia 0.31–0.37/0.07–0.08 (3.88–5.29), tarsus 0.85–0.86/0.07 (12.14–12.29). Leg IV: trochanter 0.29–0.34/0.16–0.18 (1.81–1.89), femoropatella 1.13– 1.22/0.22–0.27 (4.52–5.50), tibia 0.70–0.79/0.11 (6.36– 7.18), basitarsus 0.34–0.39/0.09–0.10 (3.40–4.33), telotarsus 0.94–0.98/0.06–0.08 (11.75–16.16).

Remarks. Lagynochthonius guanniuensis was described from two female specimens by Hou, Feng & Zhang (2023). Additonal specimens were collected recently at the type locality (Guanniu Cave in Guiyang City, Guizhou Province, China), including ten males and six females, which conform to the diagnostic characteristics of L. guanniuensis . We also refine the diagnosis of L. guanniuensis based on the holotype and the new specimens examined.

Lagynochthonius guanniuensis differs from all other hypogean species of the genus except L. fengi , L. serratus and L. xiaolinensis by both chelal fingers with intercalary teeth, the presence of two setae on tergites Ⅰ–III and Ⅹ, and carapace without eyes or eyespots. It differs from L. fengi , L. serratus and L. xiaolinensis by its longer chela (1.88– 1.99 mm (♂), 1.89–2.01 mm (♀) compared to 1.53–1.54 mm (♂), 1.53–1.55 mm (♀) in L. fengi , 1.68–1.76 mm (♂), 1.79–1.81 mm (♀) in L. serratus and 1.75 mm (♂) in L. xiaolinensis ) and the markedly curved chelal fingers in dorsal view (straight or slightly curved in dorsal view in L. fengi , L. serratus and L. xiaolinensis ) ( Hou et al. 2022b).

Ecology. All the specimens were collected from the stone walls inside the cave ( Fig. 26C–D).

Distribution. Known only from the type locality, Guanniu Cave 1 ( China, Guizhou Province).