Tyrannochthonius maculosus, 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 : 73-79

Tyrannochthonius maculosus sp. nov. ‹AEṀƟṁae›

Figs 57–61

Type material. Holotype ♂ (Ps.- MHBU-HBUARA#2022-504 - 01 ): China, Guizhou Province, Xingren City, Xinlongchang Town, Lianzhuang Village , Daxiao Cave , under stones, detritus and on the cave walls within 200– 400 m from the cave entrance (Temperature: 15°C, Humidity: 85%) [25°26′16.92″N, 105°6′58.31″E], 1473 m a.s.l., 5 August 2022, Yanmeng Hou, Lu Zhang, Jianzhou Sun & Wenlong Fan leg. Paratypes: 14 ♂ (Ps.-MHBU-HBUARA#2022-504-02–HBUARA#2022-504-15), 6 ♀ (Ps.-MSWU- HBUARA#2022-504-16–HBUARA#2022- 504-21), all with the same data as the holotype .

Etymology. The specific name is derived from the Latin word “ maculosus ”, meaning speckled, which refers to the speckled tergites.

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–III each with 4 setae. Pedipalps slender, femur 6.47–6.80 (♂), 6.67–6.80 (♀) times longer than broad; chela 6.81–7.45 (♂), 6.55 (♀) times longer than broad; both chelal fingers with intercalary teeth.

Description. Males (holotype and paratypes) ( Figs 57F , 58A , 59A–F , 60 , 61 ).

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

Cephalothorax ( Figs 59C , 60A ): carapace 1.02–1.04 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 3–4, 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 9–10 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. 60C ); intercoxal tubercle absent; without sub-oral seta.

Chelicera ( Figs 59D , 60B ): large, about as long as carapace, 2.22–2.33 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 12–14 teeth, distal one largest; movable finger with 14–17 retrorse contiguous small teeth; galea completely vestigial ( Fig. 60B ). Serrula exterior with 18–21 and serrula interior with 14–15 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. 60E ).

Pedipalp ( Figs 59A, B, E , 60D , 61A, B ): long and slender, trochanter 1.22–1.35, femur 6.47–6.80, patella 2.22–2.28, chela 6.81–7.45, hand 2.38–2.65 times longer than broad; femur 2.43–2.49 times longer than patella; movable chelal finger 1.83–1.90 times longer than hand and 0.65–0.66 times longer than chela. Setae generally long and acuminate; 1 distal lyrifissure present on patella ( Figs 59E , 60D ). 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 midway between st and b; b and t situated subdistally, t situated at same level as it; est situated distal to b ( Fig. 61C ). 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 34–35 macrodenticles, slightly retrorse and pointed, plus 24– 25 intercalary microdenticles, 58–60 in total; movable chelal finger with 20–22 macrodenticles (slightly smaller than teeth on fixed chelal finger), slightly retrorse and pointed, plus 18– 19 intercalary microdenticles and 12–14 vestigial, rounded and contiguous basal teeth, 52–53 in total ( Fig. 61C ). Chelal fingers slightly curved in dorsal view; microsetae (chemosensory setae) present on dorsum of chelal hand ( Figs 59B , 61B ).

Opisthosoma: generally typical, pleural membrane finely granulated. Tergites and sternites undivided; setae uniseriate and acuminate. Tergal chaetotaxy I–XII: 4: 4: 4: 4–5: 4–5: 5: 5: 5–6: 5: 4: T2T: 0; tergite IX with an unpaired median seta. Sternal chaetotaxy III–XII: 14–15: 13–14: 9–10: 8–10: 9–10: 9: 9: 9: 0: 2. Anterior genital operculum with 10 setae, genital opening slit-like, with 17–22 marginal setae on each side, 45–50 in total ( Fig. 59F ).

Legs ( Fig. 61C, D ): generally typical, long and slender. Fine granulation present on anterodorsal faces of femur IV and patella IV. Femur of leg I 1.94–1.97 times longer than patella and with 1 lyrifissure at the base of femur; tarsus 2.33–2.36 times longer than tibia. Femoropatella of leg IV 3.63–3.79 times longer than deep; tibia 5.82–6.00 times longer than deep; with basal tactile setae on both tarsal segments: metatarsus 3.11–3.63 times longer than deep (TS= 0.21–0.24), tarsus 11.83–12.67 times longer than deep and 2.54–2.62 times longer than metatarsus (TS= 0.28–0.32). Arolium slightly shorter than the claws, not divided; claws simple.

Adult females (paratypes) ( Figs 58B , 59G ). Mostly same as males, but a little larger; chaetotaxy of coxae: P 3, I 3, II 4, III 5, IV 5; tergal chaetotaxy I–XII: 4: 3–4: 4: 4–5: 5–6: 5–7: 5–6: 5–6: 5–6: 4: T2T: 0; sternal chaetotaxy IV–XII: 14: 10: 9–10: 9–10: 9–10: 10: 9–10: 0: 2; anterior genital operculum with 12 setae, posterior margin with 14–15 marginal setae, 26–27 in total; leg IV with a long tactile seta on both tarsal segments: metatarsus 3.00–3.22 times longer than deep (TS= 0.24–0.25), tarsus 11.33–12.33 times longer than deep and 2.55–2.83 times longer than metatarsus (TS= 0.34–0.35).

Dimensions (length/breadth or, in the case of the legs, length/depth in mm; ratios in parentheses). Males: body length 2.22–2.31. Pedipalps: trochanter 0.22–0.23/0.17–0.18 (1.22–1.35), femur 0.97–1.02/0.15 (6.47–6.80), patella 0.40–0.41/0.18 (2.22–2.28), chela 1.43–1.49/0.20–0.21 (6.81–7.45), hand 0.50–0.53/0.20–0.21 (2.38–2.65), movable chelal finger length 0.95–0.97. Chelicera 0.60–0.63/0.27 (2.22–2.33), movable finger length 0.33–0.35. Carapace 0.59/0.57–0.58 (1.02–1.04). Leg I: trochanter 0.17–0.19/0.14–0.15 (1.21–1.27), femur 0.60–0.61/0.08 (7.50–7.63), patella 0.31/0.07–0.08 (3.88–4.43), tibia 0.27–0.28/0.06 (4.50–4.67), tarsus 0.63–0.66/0.06 (10.50– 11.00). Leg IV: trochanter 0.25–0.27/0.15–0.16 (1.67–1.69), femoropatella 0.87–0.91/0.24 (3.63–3.79), tibia 0.64– 0.66/0.11 (5.82–6.00), metatarsus 0.28–0.29/0.08–0.09 (3.11–3.63), tarsus 0.71–0.76/0.06 (11.83–12.67).

Females: body length 2.50–2.59. Pedipalps: trochanter 0.22/0.18–0.19 (1.16–1.22), femur 1.00–1.02/0.15 (6.67–6.80), patella 0.40/0.18–0.19 (2.11–2.22), chela 1.44/0.22 (6.55), hand 0.51/0.22 (2.32), movable chelal finger length 0.94. Chelicera 0.64–0.65/0.29–0.30 (2.17–2.21), movable finger length 0.35. Carapace 0.61–0.62/0.62–0.63 (0.98). Leg I: trochanter 0.18/0.15–0.16 (1.13–1.20), femur 0.58–0.61/0.08–0.09 (6.44–7.63), patella 0.30–0.32/0.08 (3.75–4.00), tibia 0.27–0.28/0.06–0.07 (3.86–4.67), tarsus 0.60–0.64/0.06 (10.00–10.67). Leg IV: trochanter 0.27– 0.28/0.15 (1.80–1.87), femoropatella 0.90–0.92/0.23 (3.91–4.00), tibia 0.65–0.70/0.11 (5.91–6.36), metatarsus 0.24–0.29/0.08–0.09 (3.00–3.22), tarsus 0.68–0.74/0.06 (11.33–12.33).

Remarks. Tyrannochthonius maculosus sp. nov. is similar to T. multidentatus sp. nov. in having intercalary teeth on both chelal fingers and a pointed epistome, but differs by the trait of teeth on movable chelal finger (slightly retrorse and well-spaced vs. markedly retrorse and continuous), the relative position of trichobothrium sb (sb midway between st and b vs. closer to b) and the number of blades of rallum (8 vs. 6).

Tyrannochthonius maculosus sp. nov. can be distinguished from T. chixing , T. harveyi and T. zhai by the presence of intercalary teeth on both chelal fingers, 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 6.81–7.45 (♂), 6.55 (♀) vs. 7.90–8.00 (♂), 6.90–7.55 (♀) times longer than broad; palpal femur 6.47–6.80 (♂), 6.67–6.80 (♀) vs. 7.30–8.30 (♂), 7.10–7.50 (♀) times longer than broad) and the relative position of trichobothrium sb (sb midway between st and b vs. closer to b) ( Mahnert 2009; Gao et al. 2018, 2020).

Distribution. Known only from the type locality.

Figures

FIGURE 57. Daxiao Cave, type locality of Tyrannochthonius maculosus sp. nov., A. Cave location (red arrow); B. Entrance; C. Inside the cave entrance; D–E. Areas where T. maculosus sp. nov. specimens were collected; F. Live male of T. maculosus sp. nov. in its natural environment.

FIGURE 58. Tyrannochthonius maculosus sp. nov., A. Holotype male, habitus (dorsal view); B. Paratype female, habitus (dorsal view).

FIGURE 59. Tyrannochthonius maculosus 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 60. Tyrannochthonius maculosus 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 61. Tyrannochthonius maculosus 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.