Tyrannochthonius qilinensis, 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 : 130-133

Tyrannochthonius qilinensis sp. nov. ‹ḆĦƟṁae›

Figs 107–110

Type material. Holotype ♀ (Ps.-MHBU-GZJH-19-26-35): China, Guizhou Province, Jianhe County, Yangasha Sub-district, Chuandong Village , Qilin Cave , under a stone in the deep zone (Temperature: 15°C, Humidity: 80%) [26°45′58.07″N, 108°27′42.06″E], 743 m a.s.l., 13 October 2019, Zegang Feng & Lingchen Zhao leg.

Etymology. Named after the type locality, Qilin Cave.

Diagnosis (♀). Moderately sized troglomorphic species with elongated appendages; carapace without eyes or eyespots; anterior margin of carapace thin, finely denticulated, epistome small and pointed, represented by a bump; posterior margin of carapace with 2 setae; tergites I–VI each with 2 setae. Pedipalps slender, femur 7.72 times longer than broad; chela 7.62 times longer than broad; both chelal fingers with intercalary teeth, but present at fingertips only; chelal fingers curved in dorsal view; chemosensory setae present on dorsum of chelal hand.

Description. Female (holotype), male unknown ( Figs 107–110 ).

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

Cephalothorax ( Figs 108C , 109A ): carapace 0.93 times longer than broad, gently narrowed posteriorly; surface smooth, without furrows; no traces of eyes; anterior margin slightly serrate; epistome small and pointed, represented by a bump, with 2 setae flanking base; 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 the 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 11–12 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. 109C ); intercoxal tubercle absent; without sub-oral seta.

Chelicera ( Figs 108D , 109B ): large, about as long as carapace, 2.38 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 17 teeth, distal one largest; movable finger with 13 retrorse contiguous small teeth; galea completely vestigial ( Fig. 109B ). Serrula exterior with 18 and serrula interior with 13 blades. Rallum with 8 blades, the distal one longer 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. 109E ).

Pedipalp ( Figs 108A, B, F , 109D , 110A, B ): long and slender, trochanter 1.45, femur 7.72, patella 2.65, chela 7.62, hand 2.88 times longer than broad; femur 2.28 times longer than patella; movable chelal finger 1.67 times longer than hand and 0.63 times longer than chela. Setae generally long and acuminate; one distal lyrifissures present on patella ( Figs 108F , 109D ). 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 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, b situated at same level as it and proximal to t ( Fig. 110A ). 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 43 macrodenticles, slightly retrorse and pointed, plus 4 intercalary microdenticles (present at fingertip only, till et), 47 in total; movable chelal finger with 35 macrodenticles (slightly smaller than teeth on fixed chelal finger), slightly retrorse and pointed, plus 4 intercalary microdenticles (present at fingertip only, till et on fixed chelal finger) and 10 vestigial, rounded and contiguous basal teeth, 49 in total ( Fig. 110A ). Chelal fingers markedly curved in dorsal view; microsetae (chemosensory setae) present on dorsum of chelal hand ( Figs 108B , 110B ).

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: 5: 4: 5: 4: T2T: 0. Sternal chaetotaxy IV–XII: 13: 10: 7: 8: 7: 9: 7: 0: 2. Anterior genital operculum with 11 setae, genital opening slit-like, with 14 marginal setae on each side, 25 in total ( Fig. 108E ).

Legs ( Fig. 110C, D ): generally typical, long and slender. Fine granulation present on anterodorsal faces of femur IV and patella IV. Femur of leg I 2.00 times longer than patella and with 1 lyrifissure at the base of femur; tarsus 2.39 times longer than tibia. Femoropatella of leg IV 5.08 times longer than deep; tibia 6.23 times longer than deep; with basal tactile setae on both tarsal segments: metatarsus 4.30 times longer than deep (TS= 0.30), tarsus 14.00 times longer than deep and 2.28 times longer than metatarsus (TS= 0.27). 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). Female: body length 2.41. Pedipalps: trochanter 0.32/0.22 (1.45), femur 1.39/0.18 (7.72), patella 0.61/0.23 (2.65), chela 1.98/0.26 (7.62), hand 0.75/0.26 (2.88), movable chelal finger length 1.25. Chelicera 0.76/0.32 (2.38), movable finger length 0.40. Carapace 0.68/0.73 (0.93). Leg I: trochanter 0.25/0.18 (1.39), femur 0.86/0.10 (8.60), patella 0.43/0.09 (4.78), tibia 0.38/0.07 (5.43), tarsus 0.91/0.07 (13.00). Leg IV: trochanter 0.34/0.19 (1.79), femoropatella 1.27/0.25 (5.08), tibia 0.81/0.13 (6.23), metatarsus 0.43/0.10 (4.30), tarsus 0.98/0.07 (14.00).

Remarks. Male unknown. Tyrannochthonius qilinensis sp. nov. is similar to T. akaelus in having intercalary teeth on both chelal fingers and a small epistome, but differs by a larger body size (body length 2.41 vs. 2.10 mm; chela length 1.98 vs. 1.28 mm; palpal femur 7.72 vs. 6.60 times longer than board, length 1.39 vs. 0.90 mm; movable chelal finger 1.67 vs. 2.10 times longer than hand; femoropatella of leg IV length 1.27 vs. 0.79 mm), the number of setae on tergite IV (2 vs. 4) and the position of trichobothrium t (t situated distal to est vs. at same level as it / est).

It is worth mentioning that T. qilinensis sp. nov. is similar to T. pandus in having a pair of curved chelal fingers, but differs by the presence of intercalary teeth on both chelal fingers and a larger body size (body length 2.41 vs. 1.67 mm; chela 7.62 vs. 7.06 times longer than board, length 1.98 vs. 1.20 mm; palpal femur 7.72 vs. 6.77 times longer than board, length 1.39 vs. 0.88 mm) ( Hou et al. 2022a).

Tyrannochthonius qilinensis sp. nov. can be distinguished from T. chixing , T. zhai and T. harveyi by the presence of intercalary teeth on both chelal fingers and the number of setae at the anterior margin of the carapace (6 vs. 4), from T. antridraconis by the number of setae on the tergites I–IV (2 vs. 4), from T. ganshuanensis by the number of setae on tergite IV (2 vs. 4), a larger size (body length 2.41 (♀) vs. 1.40–1.80 (♀) mm; chela 7.62 (♀) vs. 6.90–7.30 (♀) times longer than board, length 1.98 (♀) vs. 1.21–1.44 (♀) mm; palpal femur 7.72 (♀) vs. 5.90–6.70 (♀) times longer than board, length 1.39 (♀) vs. 0.95–0.97 (♀) mm; movable chelal finger 1.67 (♀) vs. 2.00–2.20 (♀) times longer than hand) and the relative position of trichobothrium sb (sb closer to st than to b vs. closer to b) ( Mahnert 2009; Gao et al. 2018, 2020).

Distribution. Known only from the type locality.

Figures

FIGURE 107. Tyrannochthonius qilinensis sp. nov., holotype female, habitus (dorsal view).

FIGURE 108. Tyrannochthonius qilinensis 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 109. Tyrannochthonius qilinensis 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: 0.20 mm (A–B, D); 0.10 mm (C, E).

FIGURE 110. Tyrannochthonius qilinensis 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: 0.20 mm.