Tyrannochthonius yanshanensis, Hou & Feng & Zhang, 2023

Hou, Yanmeng, Feng, Zegang & Zhang, Feng, 2023, Diversity of cave-dwelling pseudoscorpions from Guizhou in China, with the description of twenty-four new species of the genus Tyrannochthonius (Pseudoscorpiones, Chthoniidae), Zootaxa 5262 (1), pp. 1-158 : 148-153

Tyrannochthonius yanshanensis sp. nov. ‹ȒƜƟṁae›

Figs 121–125

Type material. Holotype ♀ (Ps.-MHBU-GZWC-20-17-01): China, Guizhou Province, Wuchuan County, Yanshan Town, Yanshan Village , Yanshan Cave , on the cave walls in the deep zone (Temperature: 17°C, Humidity: 70%) [28°48′11.32″N, 107°53′47.07″E], 951 m a.s.l., 24 August 2020, Zegang Feng, Hongru Xu & Yanmeng Hou leg. Paratype: 1 ♀ (Ps.-MSWU-GZWC-20-17-02), with the same data as the holotype .

Etymology. Named after the type locality, Yanshan Cave.

Diagnosis (♀). Small-sized troglomorphic species with slightly elongated appendages; carapace without eyes or eyespots; anterior margin of carapace thin, finely denticulated, epistome small, rounded and obtuse, represented a slight bump; posterior margin of carapace with 2 setae; tergites I–III each with 4 setae. Palpal femur 4.92–5.08 times longer than broad; chela 5.69–5.75 times longer than broad; both chelal fingers with intercalary teeth; chemosensory setae present on dorsum of chelal hand.

Description. Female (holotype and paratype), male unknown ( Figs 122–125 ).

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

Cephalothorax ( Figs 123C , 124A ): carapace 0.83–0.87 times longer than broad, gently narrowed posteriorly; surface smooth, without furrows; no traces of eyes; anterior margin slightly serrate; epistome small, rounded and obtuse, represented by a slight bump; 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 more than 1/2 length of medial seta; apex of coxa I with small, rounded anteromedial process; coxae II with 7–8 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. 124C ); intercoxal tubercle absent; without sub-oral seta.

Chelicera ( Figs 123D , 124B ): large, about as long as carapace, 1.96–2.04 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 both dorsal and ventral side. Both fingers well provided with teeth, fixed finger with 13 teeth, distal one largest; movable finger with 12–13 retrorse contiguous small teeth; galea completely vestigial ( Fig. 124B ). Serrula exterior with 18 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. 124E ).

Pedipalp ( Figs 123A, B, F , 124D , 125A, B ): long and slender, trochanter 1.17–1.33, femur 4.92–5.08, patella 1.86–1.93, chela 5.69–5.75, hand 1.81 times longer than broad; femur 2.19–2.35 times longer than patella; movable chelal finger 2.17–2.21 times longer than hand and 0.69–0.70 times longer than chela. Setae generally long and acuminate; 1 distal lyrifissure present on patella ( Figs 123F , 124D ). Chelal palm not constricted towards fingers, apodeme complex of movable chelal finger only slightly 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 nearly 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 closer to st than to b; b and t situated subdistally, t situated distal to b and at same level as est ( Fig. 125A ).A tiny antiaxial 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 and well-spaced teeth present in the middle of the row, becoming smaller and closer distally and proximally: fixed chelal finger with 29–30 macrodenticles, slightly retrorse and pointed, plus 14– 15 intercalary microdenticles, 44 in total; movable chelal finger with 9 macrodenticles (slightly smaller than teeth on fixed chelal finger), slightly retrorse and pointed, plus 8 intercalary microdenticles and 20–22 vestigial, rounded and contiguous basal teeth, 37–39 in total ( Fig. 125A ). Chelal fingers slightly curved in dorsal view; microsetae (chemosensory setae) present on dorsum of chelal hand ( Figs 123B , 125B ).

Opisthosoma: generally typical, pleural membrane finely granulated. Tergites and sternites undivided; setae uniseriate and acuminate. Tergal chaetotaxy I–XII: 4: 4: 4: 4–5: 5: 5: 5–6: 6: 6: 5: T2T: 0, tergites VI–IX each with an unpaired median seta. Sternal chaetotaxy IV–XII: 12–13: 9–10: 9–10: 9: 10–11: 9–11: 9: 0: 2. Anterior genital operculum with 10 setae, genital opening slit-like, with 12–13 marginal setae on each side, 22–23 in total ( Fig. 123E ).

Legs ( Fig. 125C, D ): generally typical, long and slender. Fine granulation present on anterodorsal faces of femur IV and patella IV. Femur of leg I 1.87–2.13 times longer than patella and with 1 lyrifissure at the base of femur; tarsus 2.06–2.19 times longer than tibia. Femoropatella of leg IV 2.59–2.65 times longer than deep; tibia 3.88–4.13 times longer than deep; with basal tactile setae on both tarsal segments: metatarsus 2.50 times longer than deep (TS= 0.33), tarsus 7.75–8.00 times longer than deep and 2.07–2.13 times longer than metatarsus (TS= 0.23–0.25). Arolium slightly shorter than the claws, not divided; claws simple.

Dimensions (length/breadth or, in the case of the legs, length/depth in mm; ratios in parentheses). Females: body length 1.29–1.33. Pedipalps: trochanter 0.14–0.16/0.12 (1.17–1.33), femur 0.59–0.61/0.12 (4.92–5.08), patella 0.26–0.27/0.14 (1.86–1.93), chela 0.91–0.92/0.16 (5.69–5.75), hand 0.29/0.16 (1.81), movable chelal finger length 0.63–0.64. Chelicera 0.49–0.51/0.25 (1.96–2.04), movable finger length 0.27. Carapace 0.43–0.45/0.52 (0.83–0.87). Leg I: trochanter 0.12/0.10–0.11 (1.09–1.20), femur 0.28–0.32/0.06 (4.67–5.33), patella 0.15/0.06 (2.50), tibia 0.16–0.17/0.05 (3.20–3.40), tarsus 0.35/0.04–0.05 (7.00–8.75). Leg IV: trochanter 0.15–0.16/0.10 (1.50–1.60), femoropatella 0.44–0.45/0.17 (2.59–2.65), tibia 0.31–0.33/0.08 (3.88–4.13), metatarsus 0.15/0.06 (2.50), tarsus 0.31–0.32/0.04 (7.75–8.00).

Remarks. Male unknown. Tyrannochthonius yanshanensis sp. nov. is similar to T. breviculus sp. nov. in having intercalary teeth on both chelal fingers and a small, rounded and obtuse epistome, but differs by a longer palp (chela length 0.91–0.92 (♀) vs. 0.78–0.79 (♀) mm; palpal femur 4.92–5.08 (♀) vs. 5.00–5.30 (♀) times longer than board, length 0.59–0.61 (♀) vs. 0.53–0.55 (♀) mm; movable chelal finger 2.17–2.21 (♀) vs. 2.04 (♀) times longer than hand), the number of setae on the tergites VIII‒IX (6 vs. 5), the relative position of trichobothrium sb (sb nearer st than b vs. midway between st and b) and the number of blades of rallum (7 vs. 8).

Tyrannochthonius yanshanensis sp. nov. can be distinguished from T. chixing , T. harveyi and T. zhai by the presence of intercalary teeth on the movable chelal finger, from T. akaelus and T. ganshuanensis by the number of setae on tergites Ⅰ–II (4 vs. 2) and from T. antridraconis by a smaller size (body length max. 1.33 mm vs. min. 1.80 mm; chela 5.69–5.75 vs. 6.90–7.55 times longer than board, length 0.91–0.92 vs. 1.68–1.70 mm; palpal femur 4.92–5.08 vs. 7.10–7.50 times longer than board) ( Mahnert 2009; Gao et al. 2018, 2020).

Distribution. Known only from the type locality.

Figures

FIGURE 121. Yanshan Cave, type locality of Tyrannochthonius yanshanensis sp. nov., A. Entrance; B–C. Passage and area where T. yanshanensis sp. nov. specimens were collected (red arrow); D. Live female of T. yanshanensis sp. nov. in its natural environment.

FIGURE 122. Tyrannochthonius yanshanensis sp. nov., holotype female, habitus (dorsal view).

FIGURE 123. Tyrannochthonius yanshanensis sp. nov., holotype female (A–F): A. Left chela (lateral view); B. Left chela (dorsal view); C. Carapace (dorsal view); D. Left chelicera (dorsal view); E. Female genital area (ventral view); F. Left pedipalp (minus chela, dorsal view).

FIGURE 124. Tyrannochthonius yanshanensis sp. nov., holotype female: A. Carapace (dorsal view); B. Left chelicera (dorsal view), with details of teeth; C. Coxal spines on coxae II (ventral view); D. Left pedipalp (minus chela, dorsal view); E. Rallum. Scale bars: 0.10 mm.

FIGURE 125. Tyrannochthonius yanshanensis sp. nov., holotype female: A. Left chela (lateral view), with details of teeth and with trichobothrial pattern; B. Left chela (dorsal view); C. Leg I (lateral view); D. Leg IV (lateral view). Scale bars: 0.10 mm.