Tyrannochthonius capito, Hou & Feng & Zhang, 2023

Hou, Yanmeng, Feng, Zegang & Zhang, Feng, 2023, Three new species of cave-adapted pseudoscorpions (Pseudoscorpiones, Chthoniidae) from eastern Yunnan, China, ZooKeys 1153, pp. 73-95 : 73

Tyrannochthonius capito sp. nov.

Figs 6 , 7 , 8 , 9 Chinese name: 大头暴伪蝎

Type material.

Holotype: China • ♂; Yunnan Province, Xichou County, Jijie Township, Xianrendong Village, Xianren Cave; 23°30.124'N, 104°52.082'E; 1345 m a.s.l.; 16 Oct. 2021; Zegang Feng, Yanmeng Hou, Lu Zhang and Liu Fu leg.; under a stone in the dark zone; Ps.-MHBU-HBUARA#2021-443-01 (Figs 1B , 6 ). Paratypes: • 1 ♂, 2 ♀; the same data as the holotype; Ps.-MSWU-HBUARA#2021-443-02-HBUARA#2021-443-04.

Diagnosis

(♂♀). Small-sized cavernicolous species with slightly elongated appendages; carapace with two anterior corneate eyes only; anterior margin of carapace thin, finely denticulated, epistome small, pointed, triangular; posterior margin of carapace with two setae; tergites I-III each with four setae. Pedipalps slender, femur 4.30-4.67 (♂), 4.27-4.60 (♀) × longer than broad; chela 4.77-5.23 (♂), 4.53-4.73 (♀) × longer than deep; both chelal fingers with intercalary teeth.

Etymology.

The specific name is derived from the Latin noun Tyrannochthonius capito (big head) and refers to the presence of a large cephalothorax.

Description.

Adult males (Figs 6D , 7A , 8A-F , 9 ). Color: generally pale yellow, chelicerae, pedipalps and tergites slightly darker, soft parts pale. Cephalothorax (Figs 8C , 9A ): carapace 0.88-0.95 × longer than broad, gently narrowed posteriorly; surface smooth, without furrows; with two anterior eyes only; anterior margin slightly serrate; epistome small, 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 three pairs of lyrifissures, the first two pairs situated middle and lateral to the setae of ocular row respectively, the third situated exterior to the sole pair of setae of posterior row. Chaetotaxy of coxae: P 3, I 3-5, 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; coxa II with seven or eight terminally indented coxal spines on each side, set as an oblique and arc row, longer spines present in the middle of the row, becoming shorter distally and proximally and incised for ca. half their length (Fig. 9C ); intercoxal tubercle absent; without sub-oral seta. Chelicera (Figs 8D , 9B, D ): large, ca. as long as carapace, 2.00 × longer than broad; five setae and two 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 seven or nine acute teeth, distal one largest; movable finger with seven or eight rounded and contiguous small teeth; galea represented by a very slight bump on movable finger (Fig. 9B ). Serrula exterior with 19 or 20 blades and serrula interior with 16 blades. Rallum with eight 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. 9D ). Pedipalp (Figs 8A, B, E , 9E-G ): long and slender, trochanter 1.64-1.70, femur 4.30-4.67, patella 1.67-2.00, chela 4.77-5.23, hand 1.62-1.77 × longer than broad; femur 2.10-2.15 × longer than patella; movable chelal finger 2.00-2.04 × longer than hand and 0.68-0.69 × longer than chela. Setae generally long and acuminate; one distal lyrifissure present on patella (Figs 8E , 9E ). 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 eight trichobothria, movable chelal finger with four 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 situated closer to st than to b; b and t situated subdistally, t situated distal to b and at same level as est (Fig. 9F ). 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 22 or 23 macrodenticles, pointed and slightly retrorse, plus 19 or 20 intercalary microdenticles, 42 in total; movable chelal finger with nine or ten macrodenticles (slightly smaller than teeth on fixed chelal finger), pointed and slightly retrorse, plus nine intercalary microdenticles and 17 or 18 vestigial, rounded and contiguous basal teeth, 36 in total (Fig. 9F ). Chelal fingers straight in dorsal view; microsetae (sc) present on dorsum of chelal hand (Figs 8B , 9G ). Opisthosoma: generally typical, pleural membrane finely granulated. Tergites and sternites undivided; setae uniseriate and acuminate. Tergal chaetotaxy I-XII: 4:4:4:6:6:6:6:6:6:7:T2T:0. Sternal chaetotaxy III-XII: 13:12-14:10:9:9-10:10-12:11-12:10:0:2. Anterior genital operculum with 8 setae, genital opening slit-like, with 11 or 12 marginal setae on each side, 31 in total (Fig. 8F ). Legs (Fig. 9H, I ): generally typical, long and slender. Fine granulation present on anterodorsal faces of femur IV and patella IV. Femur of leg I 1.83-1.92 × longer than patella and with one lyrifissure at the base of femur; tarsus 2.00-2.25 × longer than tibia. Femoropatella of leg IV 1.89-2.20 × longer than deep; tibia 3.25-3.71 × longer than deep; with basal tactile setae on both tarsal segments: basitarsus 2.00-2.20 × longer than deep (TS = 0.33-0.36), telotarsus 6.25-7.00 × longer than deep and 2.27-2.33 × longer than basitarsus (TS = 0.28-0.29). Arolium slightly shorter than the claws, not divided; claws simple.

Adult females (Figs 6E , 7B , 8G ). 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: 4:4:4:6:6-7:6:6-7:6:6-7:7:T2T:0; sternal chaetotaxy IV-XII: 12-13:9-11:9:9-11:12-13:13:11-13:0:2; anterior genital operculum with 10 or 11 setae, posterior margin with 14 marginal setae, 24 or 25 in total; leg IV with a long tactile seta on both tarsal segments: basitarsus 2.00-2.17 × longer than deep (TS = 0.31-0.33), telotarsus 7.00-9.00 × longer than deep and 2.08-2.33 × longer than basitarsus (TS = 0.25-0.26).

Dimensions (length/breadth or, in the case of the legs, also for chela and hand, length/depth in mm). Males (females in parentheses): body length 1.08-1.25 (1.31-1.37). Pedipalps: trochanter 0.17-0.18/0.10-0.11 (0.19-0.20/0.10), femur 0.42-0.43/0.09-0.10 (0.46-0.47/0.10-0.11), patella 0.20/0.10-0.12 (0.23-0.24/0.11-0.12), chela 0.62-0.68/0.13 (0.68-0.71/0.15), hand 0.21-0.23/0.13 (0.24/0.15), movable chelal finger length 0.42-0.47 (0.46-0.49). Chelicera 0.34-0.38/0.17-0.19 (0.40-0.41/0.20), movable finger length 0.19-0.21 (0.22-0.23). Carapace 0.37/0.39-0.42 (0.38-0.39/0.45-0.46). Leg I: trochanter 0.10-0.11/0.08-0.09 (0.11-0.12/0.08-0.09), femur 0.22-0.23/0.06 (0.25-0.26/0.07), patella 0.12/0.05 (0.13-0.14/0.06), tibia 0.12-0.15/0.04 (0.13-0.15/0.04), tarsus 0.27-0.30/0.03-0.04 (0.27-0.28/0.04). Leg IV: trochanter 0.14/0.10-0.11 (0.14-0.16/0.10-0.11), femoropatella 0.33-0.34/0.15-0.18 (0.36-0.38/0.14-0.16), tibia 0.26/0.07-0.08 (0.27/0.07-0.08), basitarsus 0.11-0.12/0.05-0.06 (0.12-0.13/0.06), telotarsus 0.25-0.28/0.04 (0.27-0.28/0.03-0.04).

Remarks.

Tyrannochthonius capito sp. nov. is similar to an epigean species T. robustus Beier, 1951 (from Vietnam and China) in having intercalary teeth on both chelal fingers and similar body size (e.g., body length 1.08-1.25 mm vs. 1.20 mm (♂), 1.31-1.37 mm vs. 1.20 mm (♀)), but differs by the number of eyes (2 vs. 4), the presence of a hypopigmented body cuticle and the ratio of movable chelal finger and chelal hand (2.00-2.04 × vs. 1.52 × (♂), 1.92-2.04 × vs. 1.80 × (♀)) ( Beier 1951; Song 1996).

Tyrannochthonius capito sp. nov. can be easily distinguished from other Chinese cave-dwelling Tyrannochthonius species by the presence of a pair of anterior corneate eyes.

Distribution.

Known only from the type locality.

Figures

Figure 1. Study area, general cave locations, and type locality for each species, Yunnan Province, China. Each color represents an administrative region (green: Yunnan Province; red: Fuyuan County) A Daidai Cave (Lagynochthonius daidaiensis sp. nov.) B Xianren Cave (Tyrannochthonius capito sp. nov.) C, D unnamed cave and Dongtianfu Cave (T. calvatus sp. nov.).

Figure 6. Xianren Cave (type locality), habitat of Tyrannochthonius capito sp. nov. A entrance B inside the cave entrance C area where T. capito sp. nov. specimens were collected D live male of T. capito sp. nov. in its natural environment E live female of T. capito sp. nov. in its natural environment.

Figure 7. Tyrannochthonius capito sp. nov. A holotype male, habitus (dorsal view) B paratype female, habitus (dorsal view). Scale bars: 0.50 mm.

Figure 8. Tyrannochthonius capito 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). Scale bars: 0.25 mm (B, E); 0.10 mm (A, C, D, F, G).

Figure 9. Tyrannochthonius capito sp. nov., holotype male A carapace (dorsal view) B left chelicera (dorsal view) with details of dentation C coxal spines on coxae II (ventral view) D rallum E left pedipalp (minus chela, dorsal view) F left chela (lateral view) with details of dentation and trichobothrial pattern G left chela (dorsal view) H leg I (lateral view) I leg IV (lateral view). Scale bars: 0.10 mm.