Lagynochthonius guangyangensis, Sun, Guo & Zhang, 2024

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 : 198-204

Lagynochthonius guangyangensis sp. nov.

Chinese name. Ḟ养ȗ伪Dz

Figs 17–21

Type material. Holotype ♂ (Ps.- MHBU-GX2019100601 ): China, Guangxi Zhuang Autonomous Region, Baise City, Tiandon County, Silin Town, Guangyang Cave [23.518475°N, 107.393634°E], 363 m a.s.l., 6 October 2019, Zegang Feng & Lingchen Zhao leg. Paratypes: 1 ♂ (Ps.- MHBU-GX2019100602 ) and 3 ♀ (Ps.- MHBU-GX2019100603–05 ), all with the same data as the holotype .

Etymology. Named after the type locality, Guangyang Cave.

Diagnosis. (♂ ♀). Moderately sized hypogean species; carapace without eyes or eyespots, anterior margin smooth and epistome strongly point; tergites Ⅰ–ⅠⅠⅠ each with two setae, tergite ⅠV with four setae. Rallum with eight blades. Pedipalps slender, chela 8.67–9.53 (♂), 8.33–8.63 (♀) times as long as broad; femur 8.36–8.69 (♂), 7.53–8.42 (♀) 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 (holotype and paratype) ( Figs 17A, 18A–F, 19, 20).

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

Cephalothorax ( Figs 18D, 19A): carapace nearly subquadrate, 0.93–0.95 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 strongly 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 more than 1/2 length of medial seta; apex of coxa I with a rounded anteromedial process; coxae II with 9–11 terminally indented coxal spines on each side, set as an oblique and arc row, central spines slightly longer than the others ( Fig. 19D); intercoxal tubercle absent; chaetotaxy of coxae: P 3, I 3, II 4, III 5, IV 5.

Chelicera ( Figs 18C, 19B): almost as long as carapace, 1.84–1.91 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 15–16 teeth, distal one largest; movable finger with 14–15 retrorse contiguous small teeth; galea completely vestigial ( Fig. 19B). Serrula exterior with 25–27 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. 19C).

Pedipalp ( Figs 18A–B, 18E, 19E, 20A–B): trochanter 1.75–1.81, femur 8.36–8.69, patella 2.41, chela 8.67–9.53, hand 3.17–3.47 times as long as broad; femur 2.76–2.85 times as long as patella; movable chelal finger 1.72–1.75 times as long as hand and 0.63–0.64 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 slightly distal to it and distal to b; est situated distal to b and close to it ( Figs. 18A, 20A). Microsetae (chemosensory setae) present on dorsum of chelal hand ( Figs. 18B, 20B). Both chelal fingers with a row of teeth, spaced regularly along the margin, teeth smaller distally and proximally: fixed finger with 31–33 well-spaced, pointed teeth, plus 26– 31 intercalary microdenticles, and a modified accessory tooth on prolateral-retrolateral face (td, slightly distal to dx); movable finger with 20 well-spaced, pointed teeth, plus 16– 18 intercalary microdenticles and 13 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: 2: 2: 2: 4: 4: 4: 5: 5: 5: 4: T2T: 0. Sternal chaetotaxy IV– XII: 12: 8–10: 7: 8: 9: 9: 9: -: 2. Genital region: sternite II with 8–10 setae scattered on median area, genital opening slit-like, sternite III with 20–28 setae ( Fig. 18F).

Legs ( Fig. 20C–D): fine granulation present on anterodorsal faces of femur IV and patella IV. Leg Ⅰ: femur 1.94–1.97 times as long as patella; tarsus 2.00–2.26 times as long as tibia. Leg IV: femoropatella 4.04–4.19 times as long as deep; tibia 5.40–5.80 times as long as deep; with basal tactile setae on both tarsal segments: basitarsus 3.00–3.13 times as long as deep (TS = 0.28– 0.33), telotarsus 12.40–14.00 times as long as deep and 2.58–2.80 times as long as basitarsus (TS = 0.35–0.36). Setae of leg I (trochanter to tibia) 4: 12: 9: 9, setae of leg IV (trochanter to basitarsus) 2–3: 2–3: 5–6: 9–10: 9–10. Arolium not divided, slightly shorter than the simple claws.

Adult females (paratypes) ( Figs 17B, 18G). Mostly same as males; tergal chaetotaxy Ⅰ–ⅩII: 2: 2: 2: 4: 4: 4: 5: 5: 5: 4: T2 T: 0; sternal chaetotaxy IV–ⅩII: 6–8: 8: 9: 8–9: 8–9: 9–10: 9–11: -: 2. Genital region : sternite II with 9–10 setae scattered on median area, sternite III with a row of six setae.

Dimensions (length/breadth or, in the case of the legs, length/depth in mm; ratios in parentheses). Males: body length 2.00–2.03. Pedipalps: trochanter 0.28–0.29/0.06 (1.75–1.81), femur 1.13–1.17/0.13–0.14 (8.36–8.69), patella 0.41/0.17 (2.41), chela 1.56–1.62/0.17–0.18 (8.67–9.53), hand 0.57–0.59/0.17–0.18 (3.17–3.47), movable chelal finger length 0.98–1.03. Chelicera 0.59–0.63/0.32–0.33 (1.84–1.91), movable finger length 0.33–0.35. Carapace 0.55–0.57/0.59–0.60 (0.93–0.95). Leg I: trochanter 0.17–0.18/0.10–0.11 (1.64–1.70), femur 0.59–0.66/0.08 (7.38–8.25), patella 0.30–0.34/0.07 (4.29–4.86), tibia 0.27–0.32/0.05–0.06 (5.33–5.40), tarsus 0.61–0.64/0.05–0.06 (10.67–12.20). Leg IV: trochanter 0.24–0.25/0.15–0.18 (1.33–1.67), femoropatella 0.88– 0.93/0.21–0.23 (4.04–4.19), tibia 0.54–0.58/0.10 (5.40– 5.80), basitarsus 0.24–0.25/0.08 (3.00–3.13), telotarsus 0.62–0.70/0.05 (12.40–14.00).

Females:body length2.00–2.03.Pedipalps:trochanter 0.28–0.29/0.16–0.18 (1.75–1.81), femur 1.13–1.17/0.13– 0.14 (8.36–8.69), patella 0.41/0.17 (2.41), chela 1.56– 1.62/0.17–0.19 (8.37–9.53), hand 0.57–0.59/0.17–0.19 (3.05–3.47), movable chelal finger length 0.98–1.03. Chelicera 0.59–0.65/0.32–0.35 (1.84–1.91), movable finger length 0.33–0.37. Carapace 0.55–0.60/0.59–0.64 (0.93–0.95). Leg I: trochanter 0.17–0.18/0.10–0.11 (1.64–1.70), femur 0.59–0.66/0.08 (7.38–8.25), patella 0.30–0.34/0.07 (4.29–4.86), tibia 0.27–0.32/0.05–0.06 (5.33–5.40), tarsus 0.61–0.64/0.05–0.06 (10.67–12.20). Leg IV: trochanter 0.24–0.25/0.15–0.18 (1.33–1.67), femoropatella 0.88–0.93/0.21–0.23 (4.04–4.19), tibia 0.54–0.58/0.10 (5.40–5.80), basitarsus 0.24–0.25/0.08 (3.00–3.13), telotarsus 0.62–0.70/0.05 (12.40–14.00).

Remarks. Lagynochthonius guangyangensis sp. nov. differs from all other hypogean species of the genus except L. guanniuensis , L. fengi , L. serratus and L. xiaolinensis by both chelal fingers bearing intercalary teeth, the presence of two setae on tergites Ⅰ–III and Ⅹ, and carapace without eyes or eyespots. It differs from L. guanniuensis , L. fengi , L. serratus and L. xiaolinensis by the presence of four setae on tergite IV and the strongly pointed epistome ( Hou et al. 2022b, 2023a).

Ecology. All specimens were collected under rocks and on the ground inside the cave.

Distribution. Known only from the type locality, Guangyang Cave ( China, Guangxi Zhuang Autonomous Region).