Lagynochthonius laoxueyanensis, Hou & Gao & Zhang, 2022

Hou, Yanmeng, Gao, Zhizhong & Zhang, Feng, 2022, Two new species of cave-adapted pseudoscorpions (Pseudoscorpiones, Chthoniidae) from Yunnan, China, ZooKeys 1097, pp. 65-83 : 65

Lagynochthonius laoxueyanensis sp. nov.

Chinese name. 老穴岩拉伪蝎 Figs 7 , 8 , 9 , 10

Type material.

(Figs 1B , 11 ) Holotype: China • ♂; Yunnan Province, Yanshan County, Zhela Township, Liuzhao Village, Laoxueyan Cave; 23°39.03'N, 104°35.74'E; 1665 m a.s.l.; 17 Oct. 2021; Zegang Feng, Yanmeng Hou, Lu Zhang and Liu Fu leg.; dark zone; Ps.- MHBU -HBUARA#2021-445-01. Paratypes: • 2♀; the same data as the holotype; Ps.- MHBU -HBUARA#2021-445-02, Ps.- MSWU -HBUARA#2021-445-03.

Diagnosis.

Moderately sized troglomorphic species with elongate appendages; carapace without eyes or eyespots; anterior margin of carapace thin, finely denticulate, epistome pointed and small, triangular; posterior margin of carapace with two setae; tergites I-II with two setae. Pedipalps slender, femur 8.54 times longer than broad; chela 7.71 times longer than broad; chela fingers gently curved in dorsal view and fixed finger with a modified accessory tooth on dorso-antiaxial face (td).

Etymology.

Latinized adjective derived from the name of the type locality, Laoxueyan Cave, Yunnan Province, China.

Description.

Adult male (Figs 8A , 9A-D , 10 ). Color: generally pale yellow, chelicera, pedipalps and tergites slightly darker, soft parts pale (Fig. 8A ). Cephalothorax (Figs 9B , 10A ): carapace 1.02 times longer than broad, gently narrowed posteriorly, surface smooth, without furrows but with 1 small lyrifissure; anterior margin thin, finely denticulate; without any traces of eyes; epistome very 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 (Fig. 10A ). Chaetotaxy of coxae: P 3, I 3, II 4, III 5, IV 5; manducatory process with two acuminate distal setae, anterior seta less than 1/3 length of medial seta; apex of coxa I with small, rounded anteromedial process; coxae II with 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. 10C ); intercoxal tubercle absent; without sub-oral seta. Chelicera (Figs 9C , 10B ): large, about same length as carapace, 2.37 times longer than broad; 5 setae on hand, all setae acuminate, ventrobasal seta shorter than others; movable finger with one medial seta. Cheliceral palm with moderate hispid granulation both ventral and dorsal side. Both fingers well provided with teeth, fixed finger with 12 teeth, distal one largest; movable finger with 10 retrorse continuous small teeth; galea weakly raised, keel-like (Fig. 10B ). Rallum with 8 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. 10D ). Pedipalp (Figs 9A , 10E-G ): surface of palpal segments smooth; chelal palm gradually constricted towards fingers; setae generally long and acuminate; femur 8.54, patella 2.73, chela 7.71, hand 3.10 times longer than broad; movable finger 1.45 times longer than hand and 0.58 times longer than chela, apodeme complex of movable finger strongly sclerotized. Femur and dorsal hand without tactile setae but with 1 lyrifissure distally at patella (Fig. 10E ). 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 finger, very close to chelal teeth; dx situated distal to et; sb situated closer to st than to b; b and t situated subdistally, b situated at same level as est; t situated distal to est and at same level as it (Fig. 10F ). Microsetae (chemosensory setae) absent on hand and both chelal fingers. Sensilla absent but with 1 lyrifissure between t and b, it and est, respectively (Fig. 10G ). Both chelal fingers with a row of teeth, homodentate, spaced regularly along the margin, larger teeth present in the middle of the row, becoming smaller distally and proximally: fixed finger with 24 large, erect, well-spaced teeth, without intercalary teeth; movable finger with 10 small (slightly smaller than the teeth on fixed finger), retrorse, serrated and well-spaced teeth; fixed finger also with a modified accessory tooth on dorso-antiaxial face (td) (Fig. 10F, G ). Chelal fingers gently curved in dorsal view. Opisthosoma: generally typical; pleural membrane finely granulate. Tergites and sternites undivided; setae uniseriate and acuminate. Tergal chaetotaxy I-XII: 2: 2: 4: 4: 4: 4: 4: 5: 5: 4: T2T: 0; tergites VIII and IX each with an unpaired median seta. Sternal chaetotaxy IV-XII: 13: 11: 9: 9: 9: 9: 9: 0: 2; sternites IV-X with unpaired median seta. Anterior genital operculum with 9 setae, genital opening slit-like, with 15 marginal setae on each side (Fig. 9D ). Legs (Fig. 10H, I ): generally typical, long and slender. Fine granulation present on anterodorsal faces of trochanter IV and patella IV. Femur of leg I 1.88 times longer than patella and with 1 lyrifissure at the base of femur; tarsus 2.23 times longer than tibia. Femoropatella of leg IV 3.76 times longer than deep; tibia 6.33 times longer than deep; with tactile setae on both tarsal segments: basitarsus 3.57 times longer than deep, with basal tactile setae (TS = 0.24), telotarsus 12.80 times longer than deep and 2.56 times longer than basitarsus (TS = 0.41). Setae of leg I (trochanter to tibia) 3: 11: 11: 14, setae of leg IV (trochanter to basitarsus) 2: 3: 6: 14: 10. Arolium slightly shorter than the claws, not divided; claws simple. Dimensions of male holotype (length/width or, in the case of the legs, length/depth in mm; ratios in parentheses). Body length 1.78. Pedipalps: trochanter 0.29/0.16 (1.81), femur 1.11/0.13 (8.54), patella 0.41/0.15 (2.73), chela 1.62/0.21 (7.71), hand length 0.65/0.21 (3.10), movable finger length 0.94. Chelicera 0.64/0.27 (2.37), movable finger length 0.34. Carapace 0.59/0.58 (1.02). Leg I: trochanter 0.17/0.11 (1.55), femur 0.60/0.07 (8.57), patella 0.32/0.07 (4.57), tibia 0.30/0.05 (6.00), tarsus 0.67/0.04 (16.75). Leg IV: trochanter 0.21/0.14 (1.50), femoropatella 0.79/0.21 (3.76), tibia 0.57/0.09 (6.33), basitarsus 0.25/0.07 (3.57), telotarsus 0.64/0.05 (12.80).

Adult females (Figs 7 , 8B , 9E ). Mostly same as males. Anterior genital operculum with 9 setae plus 10-12 setae on posterior margin. Body length 2.00-2.05. Pedipalps: trochanter 0.30-0.32/0.17-0.18 (1.76-1.78), femur 1.17/0.14-0.15 (7.80-8.36), patella 0.40-0.41/0.17 (2.35-2.41), chela 1.65-1.66/0.23-0.24 (6.88-7.22), hand length 0.66-0.70/0.23-0.24 (2.75-3.04), movable finger length 0.95-0.98. Chelicera 0.68-0.70/0.29-0.30 (2.33-2.34), movable finger length 0.36-0.37. Carapace 0.62/0.61 (1.02). Leg I: trochanter 0.18-0.20/0.13 (1.38-1.54), femur 0.61/0.07 (8.71), patella 0.32-0.33/0.07 (4.57-4.71), tibia 0.30/0.06 (5.00), tarsus 0.68-0.69/0.05 (13.60-13.80). Leg IV: trochanter 0.22-0.24/0.13-0.14 (1.69-1.71), femoropatella 0.81-0.82/0.21 (3.86-3.90), tibia 0.60-0.61/0.09-0.10 (6.10-6.67), basitarsus 0.26-0.27/0.06 (4.33-4.50), telotarsus 0.69/0.05 (13.80).

Remarks.

Of all Lagynochthonius species found in hypogean environments around the world, only three species, L. bailongtanensis Li, Liu & Shi, 2019 (from China), L. typhlus Muchmore, 1991 (from Jamaica) and L. curvidigitatus Mahnert, 1997 (from Spain), have no eyes, and are all highly troglomorphic species. Lagynochthonius laoxueyanensis sp. nov. is most similar to L. typhlus in having only 2 setae on tergites I-II, but the latter has intercalary teeth on the chelal fingers and a smaller body size (1.28 vs. 2.00-2.05 mm in females). Lagynochthonius laoxueyanensis sp. nov. can be easily separated from L. bailongtanensis by its smaller body size ( L. laoxueyanensis 1.78 mm in male, 2.00-2.05 mm in females; while L. bailongtanensis is 2.55-2.92 mm in males, 2.72-2.95 mm in females), the number of setae on the anterior tergites (tergites I-II with 2 setae in L. laoxueyanensis , but 4 in L. bailongtanensis ), the shape of epistome (pointed and small in L. laoxueyanensis , but obtuse and inconspicuous in L. bailongtanensis ) and the number of setae on the pedipalpal coxa (3 setae in L. laoxueyanensis , but 5 in L. bailongtanensis ). Lagynochthonius laoxueyanensis sp. nov. can be easily separated from L. curvidigitatus by the presence of a pair of curved chelal fingers in the latter and the number of setae on tergites I-II ( L. laoxueyanensis with 2 and 2 setae, respectively, but L. curvidigitatus with 3 and 4 setae, respectively) ( Muchmore 1991; Mahnert 1997; Edward and Harvey 2008; Mahnert 2011; Li et al. 2019).

Distribution.

This species is only known from the type locality, Laoxueyan Cave (Figs 1B , 11 ) which is located about 4 km southeast of Liuzhao Village (Yanshan County). The entrance of the cave is slit-shaped (18 m high and 4 m wide), and the total length of the cave is 88.5 m, and the vertical height of the cave is about 30 m. A descent access leads to the bottom of the cave. The bottom of the cave is a large space, covered with gravel, temperature around 13 °C, humidity over 90%. All of the specimens were collected from ground crevices near the end of the cave.

Figures

Figure 1. Study area, general cave locations, and type locality for each species, Yunnan Province, China A Biyu Cave, Tyrannochthonius pandus sp. nov. B Laoxueyan Cave, Lagynochthonius laoxueyanensis sp. nov.

Figure 7. Lagynochthonius laoxueyanensis sp. nov., female habitus. Photographed when it crawled on stony natural habitat.

Figure 8. Lagynochthonius laoxueyanensis sp. nov. A holotype male, dorsal view B paratype female, dorsal view. Scale bars: 0.5 mm.

Figure 9. Lagynochthonius laoxueyanensis sp. nov., holotype male (A-D), paratype female (E) A chelal fingers (lateral view) B carapace (dorsal view) C left chelicera (dorsal view) D male genital area (ventral view) E female genital area (ventral view). Scale bars: 0.1 mm.

Figure 10. Lagynochthonius laoxueyanensis sp. nov., holotype male A carapace (dorsal view) with a detail of anterior margin B left chelicera (dorsal view) with details of teeth and tip of movable finger 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 with trichobothrial pattern (abbreviations explained in Material and methods) G finger tips of chela (lateral view) with detail of modified tooth H leg I without trochanter (lateral view) I leg IV (lateral view). Scale bars: 0.25 mm (A, B, E, F, H, I); 0.10 mm (C, D, G).

Figure 11. Laoxueyan Cave, type locality of Lagynochthonius laoxueyanensis sp. nov. A entrance B the only access to the deepest part of the cave C inside the cave entrance D area where L. laoxueyanensis specimens were collected.