Lagynochthonius magnidentatus Hou & Gao & Zhang 2022, sp. nov.
Creators: name: Hou, Yanmeng
name: Gao, Zhizhong
name: Zhang, Feng
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Pseudoscorpiones
Chthoniidae
Lagynochthonius
Lagynochthonius magnidentatus

description: Lagynochthonius magnidentatus sp. nov. (巨ffiIJ伪oi)
Figs 10–13
Type material. Holotype ♂ (Ps.- MHBU-HBUARA#2021-43201): China, Yunnan Province, Fuyuan County, Huangnihe Town, Longtan Village, Xiao Cave, under stones and clods within 150–200 m from the cave entrance [25°9′54.04″N, 104°42′1.39″E], 1445 m a.s.l., 9 October 2021, Zegang Feng, Yanmeng Hou, Lu Zhang & Liu Fu leg. Paratypes: 2 ♂ (Ps.- MHBU-HBUARA#2021-43202 & HBUARA#2021-43203), 4 ♀ (Ps.-MSWU-HBUARA#2021-43204-HBUARA#2021-43207), all with the same data as the holotype.
Etymology. The specific name is derived from a combination of the Latin word “ magnus ” and “ dentatus ”, meaning large and toothed, respectively, and referring to the large fixed chelal finger teeth.
Diagnosis (♂ ♀). Moderately sized troglomorphic species with elongated appendages; carapace without eyes or eyespots; anterior margin of carapace thin, finely denticulated, with 4 setae (including preocular setae) only, epistome small, rounded and obtuse, without flanking basal setae; posterior margin of carapace with 2 setae; tergites I–IV each with 2 setae. Pedipalps slender, femur 8.14–8.77 (♂), 7.50–7.75 (♀) times longer than broad; chela robust, 6.44–6.46 (♂), 5.87–6.04 (♀) times longer than broad; both chelal fingers without intercalary teeth; fixed chelal finger with a row of teeth that are distinctly larger than the teeth on movable chelal finger, pointed and slightly retrorse; chemosensory setae (sc) present on dorsum of chelal hand; sensilla absent.
Description. Males (holotype and paratypes) (Figs 10E, 11A, 12A–D, 13).
Colour (Figs 10E, 11A, 12A–D): generally pale yellow, chelicerae, pedipalps and tergites slightly darker, soft parts pale.
Cephalothorax (Figs 12B, 13A): carapace 0.98–1.04 times longer than broad, squarish, gently narrowed posteriorly; surface smooth, without furrows; no traces of eyes; anterior margin slightly serrate; epistome small, rounded and obtuse; with 14–16 setae arranged s2s: 4: 2–4: 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 8–9 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. 13C); intercoxal tubercle absent; without sub-oral seta.
Chelicera (Figs 12C, 13B): large, about as long as carapace, 2.44–2.46 times longer than broad; 5 setae and 2 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 11–12 retrorse contiguous small teeth; galea represented by a very slight bump on movable finger (Fig. 13B). Serrula exterior with 23–24 and serrula interior with 13–14 blades. Rallum with 7 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. 13D).
Pedipalp (Figs 12A, 13E–G): long and slender, trochanter 1.65–1.76, femur 8.14–8.77, patella 2.00–2.15, chela 6.44–6.46, hand 2.44–2.54 times longer than broad; femur 2.65–3.00 times longer than patella; movable chelal finger 1.57–1.62 times longer than hand and 0.61–0.62 times longer than chela. Setae generally long and acuminate; 1 distal lyrifissure present on patella (Fig. 13E). Chelal palm gradually constricted towards fingers, apodeme complex of movable chelal finger sclerotized, with weak granulation dorsally at base of fixed chelal finger and hand. Fixed chelal finger and hand with 8 trichobothria, movable chelal finger with 4 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 slightly closer to b than to st; b and t situated subdistally, t situated between it and est and distal to b; est situated distal to b (Fig. 13F). A tiny antiaxial 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 31–32 macrodenticles, pointed and gently retrorse, plus a modified accessory tooth on dorsoantiaxial face (td, near tip), 32–33 in total; movable chelal finger with 28–29 macrodenticles (markedly smaller than the teeth on fixed chelal finger), pointed and gently retrorse, plus 3–4 vestigial, rounded and contiguous basal teeth, 31–33 in total (Fig. 13F). Sensilla absent. Chelal fingers slightly curved in dorsal view; microsetae (chemosensory setae) present on dorsum of chelal hand (Fig. 13G).
Opisthosoma: generally typical, pleural membrane finely granulated. Tergites and sternites undivided; setae uniseriate and acuminate. Tergal chaetotaxy I–XII: 2: 2: 2: 2: 4: 4: 4: 4–5: 5: 2: T2T: 0, tergites IX with an unpaired median seta. Sternal chaetotaxy III–XII: 7–8: 11–13: 7–9: 8–9: 8–9: 9: 9: 7: 0: 2. Anterior genital operculum with 9–10 setae, genital opening slit-like, with 9–11 marginal setae on each side, 29–30 in total (Fig. 12D).
Legs (Fig. 13H, I): generally typical, long and slender. Fine granulation present on anterodorsal faces of femur I, IV and patella IV. Femur of leg I 1.97–2.03 times longer than patella and with 1 lyrifissure at the base of femur; tarsus 2.26–2.30 times longer than tibia. Femoropatella of leg IV 4.29–4.81 times longer than deep; tibia 7.20–7.78 times longer than deep; with basal tactile setae on both tarsal segments: basitarsus 4.13–4.57 times longer than deep (TS= 0.25–0.27), telotarsus 13.17–13.67 times longer than deep and 2.47–2.48 times longer than basitarsus (TS= 0.29–0.32). Setae of leg I (trochanter to tibia) 3–4: 7–9: 7–9: 11–12, setae of leg IV (trochanter to basitarsus) 2: 3: 6: 10–11: 10–12. Arolium slightly shorter than the claws, not divided; claws simple.
Adult females (paratypes) (Figs 10F, 11B, 12E). Mostly same as males; with same chaetotaxy of coxae as males; tergal chaetotaxy I–XII: 2: 2: 2: 2: 3–4: 4: 4: 4–5: 5: 2: T2 T: 0; sternal chaetotaxy IV –XII: 10: 8–9: 7–10: 9–10: 10: 9–10: 7: 0: 2; anterior genital operculum with 9–10 setae, posterior margin with 7–8 marginal setae, 17 in total; leg IV with a long tactile seta on both tarsal segments: basitarsus 3.89–4.13 times longer than deep (TS= 0.27–0.31), telotarsus 14.00–14.67 times longer than deep and 2.51–2.55 times longer than basitarsus (TS= 0.32–0.38).
Dimensions (length/breadth or, in the case of the legs, length/depth in mm; ratios in parentheses). Males: body length 1.95–2.15. Pedipalps: trochanter 0.28–0.30/0.17 (1.65–1.76), femur 1.14/0.13–0.14 (8.14–8.77), patella 0.38–0.43/0.19–0.20 (2.00–2.15), chela 1.55–1.61/0.24–0.25 (6.44–6.46), hand 0.61/0.24–0.25 (2.44–2.54), movable chelal finger length 0.96–0.99. Chelicera 0.61–0.64/0.25–0.26 (2.44–2.46), movable finger length 0.34– 0.35. Carapace 0.52–0.57/0.53–0.55 (0.98–1.04). Leg I: trochanter 0.18–0.19/0.12–0.14 (1.36–1.50), femur 0.67– 0.69/0.08 (8.38–8.63), patella 0.34/0.07–0.08 (4.25–4.86), tibia 0.30–0.31/0.06 (5.00–5.17), tarsus 0.69–0.70/0.06 (11.50–11.67). Leg IV: trochanter 0.25–0.29/0.15–0.16 (1.67–1.81), femoropatella 1.01–1.03/0.21–0.24 (4.29– 4.81), tibia 0.70–0.72/0.09–0.10 (7.20–7.78), basitarsus 0.32–0.33/0.07–0.08 (4.13–4.57), telotarsus 0.79–0.82/0.06 (13.17–13.67).
Females: body length 1.97–2.14. Pedipalps: trochanter 0.33–0.34/0.18–0.19 (1.79–1.83), femur 1.20–1.24/0.16 (7.50–7.75), patella 0.38–0.44/0.19–0.20 (2.00–2.20), chela 1.69–1.76/0.28–0.30 (5.87–6.04), hand 0.66–0.68/0.28– 0.30 (2.27–2.36), movable chelal finger length 1.03–1.07. Chelicera 0.66–0.69/0.28–0.29 (2.28–2.46), movable finger length 0.38. Carapace 0.60–0.62/0.59–0.61 (1.02). Leg I: trochanter 0.19–0.21/0.13–0.16 (1.31–1.46), femur 0.70–0.73/0.07–0.09 (8.11–10.00), patella 0.33–0.40/0.08–0.09 (4.13–4.44), tibia 0.30–0.32/0.06–0.07 (4.29–5.33), tarsus 0.73–0.76/0.06–0.07 (10.86–12.17). Leg IV: trochanter 0.30–0.32/0.16–0.18 (1.78–1.88), femoropatella 1.02–1.07/0.23–0.24 (4.43–4.46), tibia 0.69–0.70/0.10 (6.90–7.00), basitarsus 0.33–0.35/0.08–0.09 (3.89–4.13), telotarsus 0.84–0.88/0.06 (14.00–14.67).
Remarks. Lagynochthonius magnidentatus sp. nov. can be distinguished from other described troglomorphic Lagynochthonius species by the presence of only 2 setae on the anterior margin of the carapace (except preocular setae), the presence of anterolateral setae, and the absence of 2 long setae flanking the epistome.
Lagynochthonius magnidentatus sp. nov. is most similar to L. xinjiaoensis sp. nov. in having only 2 anterolateral setae on anterior of the carapace (except preocular setae), the same number of setae on tergites I–IV, and a similarlyshaped chelal hand, but differs by the presence of a smaller sized chela (e.g. chela 6.44–6.46 times as long as broad vs. 7.03 times, chela length 1.55–1.61 vs. 2.04 mm, movable chelal finger length 0.96–0.99 vs. 1.30 mm; all in males), epistome shape (rounded and obtuse vs. pointed and triangular), and the position of trichobothrium sb (sb 1.28–1.30 times as far from b as from st vs. 1.07 times as far from b as from st).
Compared with L. curvidigitatus Mahnert, 1997, the new species has a similarly-shaped chelal hand (especially in dorsal view) and a similar ‘reinforced’ apodeme at the base of the movable chelal finger, but lacks the strongly curved chelal fingers (Mahnert 1997).
Distribution and habitat. This species is only known from the type locality, Xiao Cave (Figs 1G, 10A–D), which is located about 0.5 km northwest of Longtan Village (Fuyuan County) near the top of a mountain, surrounded by residential areas and used as a shrine by local people. This limestone cave has one small and upright rectangle entrance (about 1.5 m high and 0.8 m wide) and the total length of the cave is unknown. Human disturbance in the entrance zone is serious, but the deep zone remains pristine. All specimens were collected under stones and clods within 150–200 m from the entrance. This space range is completely dark, with an average temperature of around 15℃ and humidity approximate to 90%.
description: Published as part of Hou, Yanmeng, Gao, Zhizhong & Zhang, Feng, 2022, Diversity of cave-dwelling pseudoscorpions from eastern Yunnan in China, with the description of eleven new species of the genus Lagynochthonius (Pseudoscorpiones, Chthoniidae), pp. 1-65 in Zootaxa 5198 (1) on pages 16-19, DOI: 10.11646/zootaxa.5198.1.1, http://zenodo.org/record/7251602