Tyrannochthonius duo, 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 : 43-48

Tyrannochthonius duo sp. nov. ‹Ξ⁂Ɵṁae›

Figs 32–36

Type material. Holotype ♂ (Ps.- MHBU-HBUARA#2022-305 - 01 ): China, Guizhou Province, Jiangkou County, Nuxi Town, Mengjiatun Village , Liangfeng Cave , under stones and detritus in the deep zone (Temperature: 13°C, Humidity: 80%) [27°49′37.84″N, 108°51′43.34″E], 408 m a.s.l., 4 July 2022, Yanmeng Hou, Nana Zhan, Long Lin & Jianzhou Sun leg. Paratypes: 2 ♀ (Ps.- MSWU-HBUARA#2022-305 - 02 & HBUARA#2022-305-03), all with the same data as the holotype .

Etymology. The specific name is derived from the Latin word “ duo ”, meaning dual, which refers to the presence of two well-developed anterior eyes.

Diagnosis (J ♀). Moderately sized troglomorphic species with elongated appendages; carapace with two anterior corneate eyes, posterior eyes reduced into eyespots; anterior margin of carapace thin, finely denticulated, epistome small, pointed, triangular; posterior margin of carapace with 2 setae; tergites I–II each with 4 setae. Pedipalps slender, femur 5.85 (♂), 5.79–6.08 (♀) times longer than broad; chela 6.94 (♂), 5.85–6.56 (♀) times longer than broad; both chelal fingers with intercalary teeth; chemosensory setae present on dorsum of chelal hand.

Description. Male (holotype) ( Figs 32D , 33A , 34A–F , 35 , 36 ).

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

Cephalothorax ( Figs 34C , 35A ): carapace 1.00 times longer than broad, gently narrowed posteriorly; surface smooth, without furrows; anterior pair of eyes well developed, posterior pair of eyes reduced into eyespots; anterior margin slightly serrate; epistome small and 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 more than 1/2 length of medial seta; apex of coxa I with small, rounded anteromedial process; coxae II with 9–11 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. 35C ); intercoxal tubercle absent; without sub-oral seta.

Chelicera ( Figs 34D , 35B ): large, about as long as carapace, 2.08 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 15 teeth, distal one largest; movable finger with 15 retrorse contiguous small teeth; galea completely vestigial ( Fig. 35B ). Serrula exterior with 17 and serrula interior with 13 blades. 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. 35E ).

Pedipalp ( Figs 34A, B, E , 35D , 36A, B ): long and slender, trochanter 1.36, femur 5.85, patella 2.27, chela 6.94, hand 2.25 times longer than broad; femur 2.24 times longer than patella; movable chelal finger 2.14 times longer than hand and 0.69 times longer than chela. Setae generally long and acuminate; 1 distal lyrifissure present on patella ( Figs 34E , 35D ). 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 b than to st; b and t situated subdistally, t situated at same level as est and distal to b ( Fig. 36A ). 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 32 macrodenticles, slightly retrorse and pointed, plus 21 intercalary microdenticles, 53 in total; movable chelal finger with 16 macrodenticles (slightly smaller than teeth on fixed chelal finger), slightly retrorse and pointed, plus 10 intercalary microdenticles and 14 vestigial, rounded and contiguous basal teeth, 40 in total ( Fig. 36A ). Chelal fingers slightly curved in dorsal view; microsetae (chemosensory setae) present on dorsum of chelal hand ( Figs 34B , 36B ).

Opisthosoma: generally typical, pleural membrane finely granulated. Tergites and sternites undivided; setae uniseriate and acuminate. Tergal chaetotaxy I–XII: 4: 4: 3: 4: 6: 7: 8: 8: 6: 4: T2T: 0, tergites VI–IX each with an unpaired median seta. Sternal chaetotaxy III–XII: 12: 12: 9: 9: 9: 10: 10: 8: 0: 2. Anterior genital operculum with 12 setae, genital opening slit-like, with 17–18 marginal setae on each side, 47 in total ( Fig. 34F ).

Legs ( Fig. 36C, D ): generally typical, long and slender. Fine granulation present on anterodorsal faces of femur IV and patella IV. Femur of leg I 2.09 times longer than patella and with 1 lyrifissure at the base of femur; tarsus 2.13 times longer than tibia. Femoropatella of leg IV 2.91 times longer than deep; tibia 4.80 times longer than deep; with basal tactile setae on both tarsal segments: metatarsus 3.29 times longer than deep (TS= 0.35), tarsus 11.60 times longer than deep and 2.52 times longer than metatarsus (TS= 0.36). Arolium slightly shorter than the claws, not divided; claws simple.

Adult females (paratypes) ( Figs 33B , 34G ). Mostly same as male, but a little larger; with same chaetotaxy of coxae; tergal chaetotaxy I–XII: 4: 4: 4: 4–6: 7–8: 8: 8: 8–9: 8–9: 4: T2T: 0; sternal chaetotaxy IV–XII: 11–13: 12: 11–12: 12: 12: 11–12: 9: 0: 2; anterior genital operculum with 11 setae, posterior margin with 12–14 marginal setae, 23–25 in total; leg IV with a long tactile seta on both tarsal segments: metatarsus 3.00–3.43 times longer than deep (TS= 0.33), tarsus 11.60–11.80 times longer than deep and 2.42–2.46 times longer than metatarsus (TS= 0.31–0.34).

Dimensions (length/breadth or, in the case of the legs, length/depth in mm; ratios in parentheses). Male: body length 1.73. Pedipalps: trochanter 0.19/0.14 (1.36), femur 0.76/0.13 (5.85), patella 0.34/0.15 (2.27), chela 1.11/0.16 (6.94), hand 0.36/0.16 (2.25), movable chelal finger length 0.77. Chelicera 0.52/0.25 (2.08), movable finger length 0.28. Carapace 0.52/0.52 (1.00). Leg I: trochanter 0.15/0.12 (1.25), femur 0.46/0.07 (6.57), patella 0.22/0.07 (3.14), tibia 0.24/0.05 (4.80), tarsus 0.51/0.04 (12.75). Leg IV: trochanter 0.19/0.14 (1.36), femoropatella 0.67/0.23 (2.91), tibia 0.48/0.10 (4.80), metatarsus 0.23/0.07 (3.29), tarsus 0.58/0.05 (11.60).

Females: body length 1.93–2.12. Pedipalps: trochanter 0.19–0.21/0.14–0.16 (1.19–1.50), femur 0.79–0.81/0.13– 0.14 (5.79–6.08), patella 0.36/0.15–0.16 (2.25–2.40), chela 1.17–1.18/0.18–0.20 (5.85–6.56), hand 0.38–0.39/0.18– 0.20 (1.95–2.11), movable chelal finger length 0.80–0.82. Chelicera 0.57–0.58/0.28–0.29 (2.00–2.04), movable finger length 0.31–0.32. Carapace 0.56/0.61–0.63 (0.89–0.92). Leg I: trochanter 0.13–0.14/0.12–0.13 (1.08), femur 0.47–0.49/0.07–0.08 (5.88–7.00), patella 0.22–0.24/0.07 (3.14–3.43), tibia 0.24/0.05 (4.80), tarsus 0.48–0.54/0.05– 0.06 (9.00–9.60). Leg IV: trochanter 0.20–0.23/0.14–0.15 (1.33–1.64), femoropatella 0.70/0.23 (3.04), tibia 0.52– 0.53/0.10 (5.20–5.30), metatarsus 0.24/0.07–0.08 (3.00–3.43), tarsus 0.58–0.59/0.05 (11.60–11.80).

Remarks. Tyrannochthonius duo sp. nov. can be distinguished from other described Chinese troglomorphic Tyrannochthonius species by the presence of a pair of well-developed anterior eyes and more setae on tergites V‒IX (6–9).

Distribution. Known only from the type locality.

Figures

FIGURE 32. Liangfeng Cave, type locality of Tyrannochthonius duo sp. nov., A. Entrance; B. Inside the cave entrance; C. Area where T. duo sp. nov. specimens were collected; D. Live male of T. duo sp. nov. in its natural environment.

FIGURE 33. Tyrannochthonius duo sp. nov., A. Holotype male, habitus (dorsal view); B. Paratype female, habitus (dorsal view).

FIGURE 34. Tyrannochthonius duo 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 35. Tyrannochthonius duo 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. Left pedipalp (minus chela, dorsal view); E. Rallum. Scale bars: 0.20 mm (A–B, D); 0.10 mm (C, E).

FIGURE 36. Tyrannochthonius duo sp. nov., holotype male: 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.