Lagynochthonius longedentatus, Hou & Feng & Zhang, 2023

Hou, Yanmeng, Feng, Zegang & Zhang, Feng, 2023, New cave-dwelling pseudoscorpions of the genus Lagynochthonius (Pseudoscorpiones, Chthoniidae) from Guizhou in China, Zootaxa 5309 (1), pp. 1-64 : 21-26

Lagynochthonius longedentatus sp. nov. (KfflṄṁae)

Figs 15–18

Type material. Holotype ♂ (Ps.- MHBU-HBUARA#2021-433 - 01 ): China, Guizhou Province, Ceheng County, Rongdu Town, Hongbaituo Village , Hongbaituo Cave , under stones in the deep zone [25°4′42.31″N, 105°43′3.96″E], 1033 m a.s.l., 10 October 2021, Zegang Feng, Yanmeng Hou, Lu Zhang & Liu Fu leg. Paratype: 1 ♀ (Ps.- MSWU-HBUARA#2021-433 - 02 ), with the same data as the holotype .

Etymology. The specific name is derived from the Latin words “ longus ” and “ dentatus ”, meaning elongate and toothed, respectively, and referring to the elongated intercalary teeth on the fixed chelal finger.

Diagnosis (♂ ♀). Moderately sized troglomorphic species with elongated appendages; carapace without eyes or eyespots; anterior margin of carapace thin, finely denticulated, epistome small, pointed, triangular; posterior margin of carapace with two setae; tergites III–VII each with four setae. Pedipalps slender, femur 7.15 (♂), 7.42 (♀) times longer than broad; chela robust, 6.65 (♂), 6.63 (♀) times longer than broad; chelal fingers with intercalary teeth; fixed chelal finger with a row of macrodenticles that are distinctly larger than movable chelal finger teeth, pointed and slightly retrorse, fixed chelal finger intercalary teeth almost as large as movable finger teeth; chemosensory setae (sc) present on dorsum of chelal hand.

Description. Male (holotype) ( Figs 20A , 17A–F , 18 ).

Colour: generally pale yellow, chelicerae, pedipalps and tergites slightly darker, soft parts pale.

Cephalothorax ( Figs 17C , 18A ): carapace 1.00 times longer than broad, squarish, gently narrowed posteriorly; surface smooth, without furrows; no traces of eyes; anterior margin slightly serrate; epistome small, pointed, triangular; with 18 setae arranged s4s: 4: 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 seven 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. 18C ); intercoxal tubercle absent; without sub-oral seta.

Chelicera ( Figs 17D , 18B ): large, about as long as carapace, 2.48 times longer than broad; five setae and two 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 17 teeth, distal one largest; movable finger with 17 retrorse contiguous small teeth; galea absent ( Fig. 18B ). Serrula exterior with 20 blades and serrula interior with 12 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. 18D ).

Pedipalp ( Figs 17A–B, E , 18E–G ): long and slender, trochanter 1.07, femur 7.15, patella 2.20, chela 6.65, hand 2.50 times longer than broad; femur 2.82 times longer than patella; movable chelal finger 1.66 times longer than hand and 0.62 times longer than chela. Setae generally long and acuminate; one distal lyrifissure present on patella ( Figs 17E , 18E ). 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 eight trichobothria, movable chelal finger with four trichobothria, ib and isb situated close together, submedially on dorsum of chelal hand; eb, esb and ist forming an 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 closer to st than to b; b and t situated subdistally, t situated distal to b and it; est situated at same level as b ( Fig. 18F ). A tiny retrolateral lyrifissure present at base of fixed chelal finger (situated distal to ist). Both chelal fingers with a row of teeth, heterodentate, spaced regularly along the margin, larger teeth present in the middle of the row, becoming smaller and closer distally and proximally: fixed chelal finger with 28 macrodenticles, slightly retrorse and pointed, plus 19 intercalary microdenticles, 47 in total; movable chelal finger with 24 macrodenticles (markedly smaller than teeth on fixed chelal finger), slightly retrorse and pointed, plus 12 intercalary microdenticles (extending roughly to the middle of sb and b) and nine vestigial, rounded and contiguous basal teeth, 45 in total ( Fig. 18F ). Chelal fingers slightly curved in dorsal view; microsetae (chemosensory setae) present on dorsum of chelal hand ( Figs 17B , 18G ).

Opisthosoma: generally typical, pleural membrane finely granulated. Tergites and sternites undivided; setae uniseriate and acuminate. Tergal chaetotaxy Ⅰ–XII: 2: 4: 4: 4: 4: 4: 4: 5: 5: 4: T2T: 0, tergites VIII and IX each with an unpaired median seta. Sternal chaetotaxy III–XII: 12: 9: 9: 9: 9: 10: 9: 7: 0: 2. Anterior genital operculum with 11 setae, genital opening slit-like, with 13–15 marginal setae on each side, 39 in total ( Fig. 17F ).

Legs ( Fig. 18H–I ): generally typical, long and slender. Fine granulation present on anterodorsal faces of femur IV and patella IV. Femur of leg Ⅰ 1.77 times longer than patella and with one lyrifissure at the base of femur; tarsus 2.46 times longer than tibia. Femoropatella of leg IV 3.48 times longer than deep; tibia 5.67 times longer than deep; with basal tactile setae on both tarsal segments: metatarsus 3.71 times longer than deep (TS = 0.35), tarsus 14.00 times longer than deep and 2.69 times longer than metatarsus (TS = 0.23). Arolium slightly shorter than the claws, not divided; claws simple.

Adult female (paratype) ( Figs 15D , 16B , 17G ). Mostly same as male; with same chaetotaxy of coxae as male; tergal chaetotaxy Ⅰ–XII: 4: 3: 4: 4: 4: 4: 4: 4: 5: 4: T2T: 0; sternal chaetotaxy IV–XII: 11: 9: 8: 9: 9: 9: 8: 0: 2; anterior genital operculum with ten setae, posterior margin with 12 marginal setae, 22 in total; leg IV with a long tactile seta on both tarsal segments: metatarsus 3.43 times longer than deep (TS = 0.38), tarsus 12.60 times longer than deep and 2.63 times longer than metatarsus (TS = 0.29).

Dimensions (length/breadth or, in the case of the legs, length/depth in mm; ratios in parentheses). Male: body length 1.42. Pedipalps: trochanter 0.16/0.15 (1.07), femur 0.93/0.13 (7.15), patella 0.33/0.15 (2.20), chela 1.33/0.20 (6.65), hand 0.50/0.20 (2.50), movable chelal finger length 0.83. Chelicera 0.57/0.23 (2.48), movable finger length 0.30. Carapace 0.49/0.49 (1.00). Leg Ⅰ: trochanter 0.15/0.14 (1.07), femur 0.53/0.07 (7.57), patella 0.30/0.06 (5.00), tibia 0.24/0.05 (4.80), tarsus 0.59/0.05 (11.80). Leg IV: trochanter 0.22/0.13 (1.69), femoropatella 0.80/0.23 (3.48), tibia 0.51/0.09 (5.67), metatarsus 0.26/0.07 (3.71), tarsus 0.70/0.05 (14.00).

Female: body length 1.59. Pedipalps: trochanter 0.18/0.14 (1.29), femur 0.89/0.12 (7.42), patella 0.30/0.15 (2.00), chela 1.26/0.19 (6.63), hand 0.49/0.19 (2.58), movable chelal finger length 0.76. Chelicera 0.55/0.22 (2.50), movable finger length 0.29. Carapace 0.47/0.48 (0.98). Leg Ⅰ: trochanter 0.14/0.12 (1.17), femur 0.52/0.07 (7.43), patella 0.28/0.06 (4.67), tibia 0.23/0.05 (4.60), tarsus 0.55/0.05 (11.00). Leg IV: trochanter 0.22/0.14 (1.57), femoropatella 0.71/0.20 (3.55), tibia 0.46/0.08 (5.75), metatarsus 0.24/0.07 (3.43), tarsus 0.63/0.05 (12.60).

Distribution. Known only from the type locality.

Figures

FIGURE 15. Hongbaituo Cave, type locality of Lagynochthonius longedentatus sp. nov., A. Entrance; B. Inside the cave entrance; C. Area where L. longedentatus sp. nov. specimens were collected; D. Live female of L. longedentatus sp. nov. in its natural environment.

FIGURE 16. Lagynochthonius longedentatus sp. nov., A. Holotype male, habitus (dorsal view); B. Paratype female, habitus (dorsal view).

FIGURE 17. Lagynochthonius longedentatus sp. nov., holotype male (A–F), paratype female (G): A. Left chela (lateral view); B. Left chela (dorsal view); C. Carapace (dorsal view); D. Left chelicera (dorsal view); E. Left pedipalp (minus chela, dorsal view); F. Male genital area (ventral view); G. Female genital area (ventral view).

FIGURE 18. Lagynochthonius longedentatus sp. nov., holotype male: A. Carapace (dorsal view); B. Left chelicera (dorsal view), with details of teeth; 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 trichobothrial pattern; G. Left chela (dorsal view); H. Leg Ⅰ (lateral view); I. Leg IV (lateral view). Scale bars: 0.20 mm (A–B, E–I); 0.10 mm (C–D).

FIGURE 20. Lagynochthonius longyanensis sp. nov., A. Holotype male, habitus (dorsal view); B. Paratype female, habitus (dorsal view).