Tyrannochthonius multidentatus, 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 : 87-93

Tyrannochthonius multidentatus sp. nov. ‹SffiƟṁae›

Figs 70–75

Type material. Holotype ♂ (Ps.-MHBU-GZFG-20-10-01): China, Guizhou Province, Fenggang County, Longquan Sub-district, Guanyin Cave , under the stones in the deep zone (Temperature: 16°C, Humidity: 85%) [27°56′40.91″N, 107°44′1.99″E], 684 m a.s.l., 20 August 2020, Zegang Feng, Hongru Xu & Yanmeng Hou leg. Paratypes: 2 ♂ (Ps.- MHBU-GZFG-20-10-02 & GZFG-20-10-03), 4 ♀ (Ps.-MHBU-GZFG-20-10-04–GZFG-20-10-07), all with the same data as the holotype; 2 ♀ (Ps.-MSWU-GZSN-20-11-01 & GZSN-20-11-02), Sinan County, Yangjiaao Township , Guanyinshan Village , Anjialin Cave [27°52′36.09″N, 107°54′49.02″E], 641 m a.s.l., 21 August 2020, with the same collectors as the holotype ; 2 ♀ (Ps.- MSWU-HBUARA#2022-475 - 01 & HBUARA#2022-475-02), Anjialin Cave , 23 July 2022, Yanmeng Hou, Lu Zhang, Jianzhou Sun & Wenlong Fan leg.

Etymology. The specific name is derived from a combination of the Latin word “ multus ” and “ dentatus ”, meaning numerous and toothed, respectively, which refers to the numerous teeth on the chelal fingers.

Diagnosis (J ♀). Moderately sized troglomorphic species with elongated appendages; carapace without eyes or eyespots; anterior margin of carapace thin, finely denticulated, epistome small and pointed, triangular; posterior margin of carapace with 2 setae; tergites I–VI each with 4 setae. Pedipalps slender, femur 7.29–7.69 (♂), 6.59–6.94 (♀) times longer than broad; chela 7.40–7.84 (♂), 6.78–7.23 (♀) times longer than broad; both chelal fingers with intercalary teeth and teeth closely arranged.

Description. Males (holotype and paratypes) ( Figs 72A , 73A–F , 74 , 75 ).

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

Cephalothorax ( Figs 73C , 74A ): carapace 1.02 times longer than broad, gently narrowed posteriorly; surface smooth, without furrows; no traces of eyes; anterior margin slightly serrate; epistome small and pointed, triangular, 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, the second situated exterior 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 9–12 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. 74C ); intercoxal tubercle absent; without sub-oral seta.

Chelicera ( Figs 73D , 74B ): large, about as long as carapace, 2.28–2.32 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 dorsal side. Both fingers well provided with teeth, fixed finger with 18–21 teeth, distal one largest; movable finger with 18–21 retrorse contiguous small teeth; galea completely vestigial ( Fig. 74B ). Serrula exterior with 17–18 and serrula interior with 11–12 blades. Rallum with 6–7 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. 74E ).

Pedipalp ( Figs 73A, B, E , 74D , 75A, B ): long and slender, trochanter 1.13–1.19, femur 7.29–7.69, patella 2.12–2.31, chela 7.40–7.84, hand 2.55–2.63 times longer than broad; femur 2.70–2.83 times longer than patella; movable chelal finger 1.82–1.94 times longer than hand and 0.63–0.65 times longer than chela. Setae generally long and acuminate; 1 distal lyrifissure present on patella ( Figs 73E , 74D ). 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. 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 b than to st; b and t situated subdistally, t situated at same level as it; est situated distal to b ( Fig. 75A ). 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 closely along the margin, larger teeth present in the middle of the row, becoming smaller distally and proximally: fixed chelal finger with 34–38 macrodenticles, slightly retrorse and pointed, plus 28– 31 intercalary microdenticles, 62–69 in total; movable chelal finger with 36–40 macrodenticles (slightly smaller than teeth on fixed chelal finger), continuous, markedly retrorse and pointed, plus 17– 18 intercalary microdenticles, 53–58 in total ( Fig. 75A ). Chelal fingers slightly curved in dorsal view; microsetae (chemosensory setae) present on dorsum of chelal hand ( Figs 73B , 75B ).

Opisthosoma: generally typical, pleural membrane finely granulated. Tergites and sternites undivided; setae uniseriate and acuminate. Tergal chaetotaxy I–XII: 4: 4: 4: 4: 4: 4: 4–5: 5–6: 5: 4–5: T2T: 0. Sternal chaetotaxy III–XII: 12: 12–13: 8: 7–8: 7–9: 7–9: 7–9: 7: 0: 2. Anterior genital operculum with 10 setae, genital opening slit-like, with 10–13 marginal setae on each side, 32–34 in total ( Fig. 73F ).

Legs ( Fig. 75C, D ): generally typical, long and slender. Fine granulation present on anterodorsal faces of femur IV and patella IV. Femur of leg I 1.84–1.93 times longer than patella and with 1 lyrifissure at the base of femur; tarsus 2.58–2.64 times longer than tibia. Femoropatella of leg IV 3.90–3.95 times longer than deep; tibia 6.33 times longer than deep; with basal tactile setae on both tarsal segments: metatarsus 3.57–3.71 times longer than deep (TS= 0.38–0.40), tarsus 14.20 times longer than deep and 2.73–2.84 times longer than metatarsus (TS= 0.41–0.42). Arolium slightly shorter than the claws, not divided; claws simple.

Adult females (paratypes) ( Figs 71D , 72B , 73G ). Mostly same as males, but a little larger; chaetotaxy of coxae: P 3, I 3, II 4, III 5, IV 5–6; tergal chaetotaxy I–XII: 4: 4: 4: 4: 4: 4: 4: 5–6: 5–6: 4: T2T: 0; sternal chaetotaxy IV–XII: 12–13: 8–10: 7–9: 7–8: 7–9: 7–9: 7: 0: 2; anterior genital operculum with 9–10 setae, posterior margin with 11–12 marginal setae, 20–22 in total; leg IV with a long tactile seta on both tarsal segments: metatarsus 3.50–4.00 times longer than deep (TS= 0.36–0.41), tarsus 12.50–13.17 times longer than deep and 2.68–2.75 times longer than metatarsus (TS= 0.38–0.46).

Dimensions (length/breadth or, in the case of the legs, length/depth in mm; ratios in parentheses). Males: body length 1.97–1.99. Pedipalps: trochanter 0.18–0.19/0.16 (1.13–1.19), femur 1.00–1.02/0.13–0.14 (7.29–7.69), patella 0.36–0.37/0.16–0.17 (2.12–2.31), chela 1.48–1.49/0.19–0.20 (7.40–7.84), hand 0.50–0.51/0.19–0.20 (2.55–2.63), movable chelal finger length 0.93–0.97. Chelicera 0.57–0.58/0.25 (2.28–2.32), movable finger length 0.30–0.31. Carapace 0.51–0.53/0.50–0.52 (1.02). Leg I: trochanter 0.15–0.16/0.14 (1.07–1.14), femur 0.57–0.58/0.08 (7.13– 7.25), patella 0.30–0.31/0.07 (4.29–4.43), tibia 0.24–0.25/0.06 (4.00–4.17), tarsus 0.62–0.66/0.05 (12.40–13.20). Leg IV: trochanter 0.23/0.14–0.15 (1.53–1.64), femoropatella 0.82–0.83/0.21 (3.90–3.95), tibia 0.57/0.09 (6.33), metatarsus 0.25–0.26/0.07 (3.57–3.71), tarsus 0.71/0.05 (14.20).

Females: body length 1.91–2.16. Pedipalps: trochanter 0.21–0.22/0.16–0.18 (1.17–1.31), femur 1.10–1.12/0.16– 0.17 (6.59–6.94), patella 0.40–0.45/0.18–0.20 (2.22–2.28), chela 1.56–1.59/0.22–0.23 (6.78–7.23), hand 0.55– 0.57/0.22–0.23 (2.39–2.55), movable chelal finger length 0.98–1.00. Chelicera 0.63–0.64/0.26–0.28 (2.29–2.42), movable finger length 0.33–0.34. Carapace 0.57–0.59/0.57–0.58 (0.98–1.04). Leg I: trochanter 0.17–0.18/0.14– 0.16 (1.06–1.29), femur 0.61–0.63/0.08–0.09 (6.78–7.75), patella 0.32–0.34/0.08 (4.00–4.25), tibia 0.26–0.27/0.06 (4.33–4.50), tarsus 0.65–0.70/0.06 (10.83–11.67). Leg IV: trochanter 0.23–0.28/0.15–0.16 (1.53–1.75), femoropatella 0.91–0.93/0.22–0.23 (4.00–4.23), tibia 0.60–0.63/0.10 (6.00–6.30), metatarsus 0.28–0.29/0.07–0.09 (3.22– 4.00), tarsus 0.75–0.79/0.06 (12.50–13.17).

Remarks. Tyrannochthonius multidentatus sp. nov. is similar to T. maculosus sp. nov. in having intercalary teeth on both chelal fingers and a small, pointed epistome, but differs by a smaller body size (body length max. 2.16 mm vs. min. 2.22 mm), the relative position of trichobothrium sb (sb closer to b than to st vs. midway between st and b), the trait of teeth on movable chelal finger (markedly retrorse and continuous, without vestigial proximal half teeth vs. slightly retrorse and well-spaced, with vestigial proximal half teeth) and the number of blades of rallum (6–7 vs. 8).

Tyrannochthonius multidentatus sp. nov. can be distinguished from T. chixing , T. harveyi and T. zhai by having intercalary teeth on both chelal fingers and the number of setae at the anterior margin of the carapace (6 vs. 4), from T. akaelus and T. ganshuanensis by the number of setae on tergites I–II (4 vs. 2), from T. antridraconis by a shorter palp (chela length max. 1.59 mm vs. min. 1.68 mm; palpal femur length max. 1.12 mm vs. min. 1.18 mm), more chelal finger teeth (fixed chelal finger with 62–69 vs. 33–36 teeth; movable chelal finger with 53–58 vs. 30–36 teeth), the number of blades of rallum (6–7 vs. 8) and coxal spines (9–12 vs. 12–15) ( Mahnert 2009; Gao et al. 2018, 2020).

Distribution. Known only from the Guanyin and Anjialin caves.

Figures

FIGURE 70. Guanyin Cave, one of the type localities of Tyrannochthonius multidentatus sp. nov., A. Entrance; B. Area where T. multidentatus sp. nov. specimens were collected; C. Live male of T. multidentatus sp. nov. in its natural environment; D. Live female of T. multidentatus sp. nov. in its natural environment.

FIGURE 71. Anjialin Cave, one of the type localities of Tyrannochthonius multidentatus sp. nov., A. Entrance; B–C. Area where T. multidentatus sp. nov. specimens were collected; D. Live female of T. multidentatus sp. nov. in its natural environment.

FIGURE 72. Tyrannochthonius multidentatus sp. nov., A. Holotype male, habitus (dorsal view); B. Paratype female, habitus (dorsal view).

FIGURE 73. Tyrannochthonius multidentatus 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 74. Tyrannochthonius multidentatus 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 75. Tyrannochthonius multidentatus 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.