Tyrannochthonius babaowanensis, 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 : 25-31

Tyrannochthonius babaowanensis sp. nov. (ÃÍẠƟṁae)

Figs 17–21

Type material. Holotype ♂ (Ps.-MHBU-GZYJ-20-14-01): China, Guizhou Province, Yinjiang County, Zhongxing Sub-district, Tianchi Village , Babaowan Cave , on a stone wall in the deep zone (Temperature: 14°C, Humidity: 85%) [28°3′53.07″N, 108°21′52.89″E], 655 m a.s.l., 23 August 2020, Zegang Feng, Hongru Xu & Yanmeng Hou leg.

Etymology. Named after the type locality, Babaowan Cave.

Diagnosis (♂). Moderately sized troglomorphic species with elongated appendages; carapace without eyes or eyespots; anterior margin of carapace thin, finely denticulated, epistome small, pointed, triangular; posterior margin of carapace with 2 setae; tergites I–VI each with 4 setae. Pedipalps slender, femur 7.67 times longer than broad; chela 7.27 times longer than broad; both chelal fingers with intercalary teeth (present in the distal 1/3 of the fingers); chemosensory setae present on dorsum of chelal hand.

Description. Male (holotype), female unknown ( Figs 17F , 18–21 ).

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

Cephalothorax ( Figs 19C , 20A ): carapace 1.04 times longer than broad, gently narrowed posteriorly; surface smooth, without furrows; no traces of eyes; anterior margin slightly serrate; epistome pointed and small, 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, 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 8–9 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. 20C ); intercoxal tubercle absent; without sub-oral seta.

Chelicera ( Figs 19D , 20B ): large, about as long as carapace, 2.37 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 14 teeth, distal one largest; movable finger with 13 retrorse contiguous small teeth; galea completely vestigial ( Fig. 20B ). Serrula exterior with 21 and serrula interior with 14 blades. Rallum with 7 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. 20E ).

Pedipalp ( Figs 19A, B, F , 21A, B ): long and slender, trochanter 1.22, femur 7.67, patella 2.72, chela 7.27, hand 2.41 times longer than broad; femur 2.35 times longer than patella; movable chelal finger 2.06 times longer than hand and 0.68 times longer than chela. Setae generally long and acuminate; one distal lyrifissures present on patella ( Figs 19F , 20D ). 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, b situated at same level as est, t slightly distal to it ( Fig. 21A ). 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 42 macrodenticles, slightly retrorse and pointed, plus 15 intercalary microdenticles (present in the distal 1/3 of the fingers, till est), 57 in total; movable chelal finger with 31 macrodenticles (slightly smaller than teeth on fixed chelal finger), slightly retrorse and pointed, plus 11 intercalary microdenticles (present in the distal 1/3 of the fingers, till b) and 14 vestigial, rounded and contiguous basal teeth, 56 in total ( Fig. 21A ). Chelal fingers slightly curved in dorsal view; microsetae (chemosensory setae) present on dorsum of chelal hand ( Figs 19B , 21B ).

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: 5: 5: 5: 2: T2T: 0. Sternal chaetotaxy III–XII: 14: 12: 7: 7: 8: 9: 9: 7: 0: 2. Anterior genital operculum with 13 setae, genital opening slit-like, with 14–15 marginal setae on each side, 42 in total ( Fig. 19E ).

Legs ( Fig. 21C, D ): generally typical, long and slender. Fine granulation present on anterodorsal faces of femur IV and patella IV. Femur of leg I 1.97 times longer than patella and with 1 lyrifissure at the base of femur; tarsus 2.43 times longer than tibia. Femoropatella of leg IV 4.21 times longer than deep; tibia 7.00 times longer than deep; with basal tactile setae on both tarsal segments: metatarsus 3.75 times longer than deep (TS= 0.33), tarsus 14.00 times longer than deep and 2.80 times longer than metatarsus (TS= 0.32). 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). Male: body length 2.35. Pedipalps: trochanter 0.22/0.18 (1.22), femur 1.15/0.15 (7.67), patella 0.49/0.18 (2.72), chela 1.60/0.22 (7.27), hand 0.53/0.22 (2.41), movable chelal finger length 1.09. Chelicera 0.64/0.27 (2.37), movable finger length 0.35. Carapace 0.59/0.57 (1.04). Leg I: trochanter 0.19/0.15 (1.27), femur 0.69/0.08 (8.63), patella 0.35/0.07 (5.00), tibia 0.30/0.06 (5.00), tarsus 0.73/0.06 (12.17). Leg IV: trochanter 0.27/0.16 (1.69), femoropatella 1.01/0.24 (4.21), tibia 0.70/0.10 (7.00), metatarsus 0.30/0.08 (3.75), tarsus 0.84/0.06 (14.00).

Remarks. Female unknown. Tyrannochthonius babaowanensis sp. nov. is similar to T. antridraconis in having intercalary teeth on both chelal fingers and a small, rounded and obtuse epistome, but differs by a larger body size (body length 1.62–1.69 (♂) vs. 1.29–1.33 (♂) mm), the number of setae on tergite VII (5 vs. 4) and tergite Ⅹ (2 vs. 4–5), the proportion of intercalary teeth on the fixed finger (1/3 vs. 2/3), the number of blades of coxal spines (8–9 vs. 12–15) and the number of blades of rallum (7 vs. 8).

Tyrannochthonius babaowanensis sp. nov. can be distinguished from T. chixing and T. zhai by the larger size (body length 2.35 vs. max. 1.64 mm; chela length 1.60 vs. max. 1.24 mm), the number of setae at the anterior margin of the carapace (6 vs. 4) and the presence of intercalary teeth on both chelal fingers, from T. akaelus , T. ganshuanensis and T. harveyi by the number of setae on the tergites I–II (4 vs. 2) ( Mahnert 2009; Gao et al. 2018, 2020).

Distribution. Known only from the type locality.

Figures

FIGURE 17. Babaowan Cave, type locality of Tyrannochthonius babaowanensis sp. nov., A. Entrance; B. Inside the cave entrance; C. A water tunnel in the cave; D–E. Area where T. babaowanensis sp. nov. specimen was collected (red arrow); F. Live male of T. babaowanensis sp. nov. in its natural environment.

FIGURE 18. Tyrannochthonius babaowanensis sp. nov., holotype male, habitus (dorsal view).

FIGURE 19. Tyrannochthonius babaowanensis sp. nov., holotype male: A. Left chela (lateral view); B. Left chela (dorsal view); C. Carapace (dorsal view); D. Left chelicera (dorsal view); E. Male genital area (ventral view); F. Left pedipalp (minus chela, dorsal view).

FIGURE 20. Tyrannochthonius babaowanensis 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 21. Tyrannochthonius babaowanensis 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.