Tyrannochthonius calvatus, 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 calvatus sp. nov.

Figs 2 , 3 , 4 , 5 Chinese name: 秃头暴伪蝎

Type material.

Holotype: China • ♂; Yunnan Province, Fuyuan County, Mohong Town, Puchong Village, unnamed cave; 25°22.301'N, 104°6.380'E; 2060 m a.s.l.; 07 Oct. 2021; Zegang Feng, Yanmeng Hou, Lu Zhang and Liu Fu leg.; under a stone in the dark zone; Ps.-MHBU-HBUARA#2021-429-01 (Figs 1C , 2A ). Paratypes: • 4 ♂; the same data as the holotype; Ps.-MHBU-HBUARA#2021-429-02-HBUARA#2021-429-05 • 1 ♂, 2 ♀; the same collection date and collectors as the holotype; Puchong Village, Dongtianfu Cave; 25°22.105'N, 104°6.447'E; 2035 m a.s.l.; under stones and clods in the dark zone; Ps.-MSWU-HBUARA#2021-428-01-HBUARA#2021-428-03 (Figs 1D , 2B ).

Diagnosis

(♂♀). Moderately sized troglomorphic species with elongated appendages; carapace without eyes or eyespots; anterior margin of carapace thin, finely denticulated, with four setae (including preocular setae) only, without epistome and flanking basal setae; posterior margin of carapace with two setae; tergites I-III each with two setae. Pedipalps slender, femur 8.06-8.44 (♂), 7.94-8.38 (♀) × longer than broad; chela 8.05-8.33 (♂), 8.05-8.71 (♀) × longer than deep only movable chelal finger with intercalary teeth; movable chelal finger teeth markedly smaller than fixed chelal finger teeth and strongly retrorse and contiguous.

Etymology.

The specific name is derived from the Latin adjective Tyrannochthonius calvatus (bald) and refers to the absence of two antero-median setae on the carapace.

Description.

Adult males (Figs 3A , 4A-F , 5 ). Color: generally pale yellow, chelicerae, pedipalps and tergites slightly darker, soft parts pale. Cephalothorax (Figs 4C , 5A ): carapace 0.98 × longer than broad, gently narrowed posteriorly; surface smooth, without furrows; no traces of eyes; anterior margin slightly serrate; epistome absent, without two setae flanking base; with 14-15 setae arranged s2s:4:4:0-1:2 (with 14-17 setae arranged s2s:4:4:0-3:2 in females), 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, II 3-4, 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 12 or 13 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. 5C ); intercoxal tubercle absent; without sub-oral seta. Chelicera (Figs 4D , 5B, D ): large, ca. as long as carapace, 2.43-2.48 × 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 14-16 teeth, distal one largest; movable finger with 13-15 retrorse contiguous small teeth; galea absent (Fig. 5B ). Serrula exterior with 25-28 blades and serrula interior with 17 or 18 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. 5D ). Pedipalp (Figs 4A, B, E , 5E-G ): long and slender, trochanter 1.74-1.88, femur 8.06-8.44, patella 2.37-2.61, chela 8.05-8.33, hand 3.00-3.10 × longer than deep femur 2.87 × longer than patella; movable chelal finger 1.64-1.66 × longer than hand and 0.61-0.62 × longer than chela. Setae generally long and acuminate; one distal lyrifissure present on patella (Figs 4E , 5E ). 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 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 situated midway between b and st; b and t situated subdistally, t situated distal to b and proximal to est (Fig. 5F ). 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 32-36 macrodenticles, long and pointed, without intercalary teeth; movable chelal finger with 37-41 macrodenticles (smaller than teeth on fixed chelal finger), retrorse and contiguous, plus 10-12 intercalary microdenticles (roughly extending to b), 47-53 in total (Fig. 5F ). Chelal fingers straight in dorsal view; microsetae (sc) present on dorsum of chelal hand (Figs 4B , 5G ). Opisthosoma: generally typical, pleural membrane finely granulated. Tergites and sternites undivided; setae uniseriate and acuminate. Tergal chaetotaxy I-XII: 2:2:2:2:4:4:4:4:4-5:4:T2-3T:0; tergite IX with an unpaired median seta. Sternal chaetotaxy III-XII: 12-14:11-12:8:9:9:9-10:9:7-9:0: 2. Anterior genital operculum with ten setae, genital opening slit-like, with 10-12 marginal setae on each side, 31-33 in total (Fig. 4F ). Legs (Fig. 5H , 5I ): generally typical, long and slender. Fine granulation present on anterodorsal faces of femur IV and patella IV. Femur of leg I 1.88 × longer than patella and with one lyrifissure at the base of femur; tarsus 2.45 × longer than tibia. Femoropatella of leg IV 4.83-5.04 × longer than deep; tibia 7.60 × longer than deep; with basal tactile setae on both tarsal segments: basitarsus 4.00-4.25 × longer than deep (TS = 0.24-0.28), telotarsus 15.33-15.50 × longer than deep and 2.71-2.91 × longer than basitarsus (TS = 0.27-0.28). Arolium slightly shorter than the claws, not divided; claws simple.

Adult females (Figs 2C , 3B , 4G ). 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: 2:2:2:2-3:4:4:3-4:4:4-5:4:T2T:0; sternal chaetotaxy IV-XII: 10-12:9-10:7-10:9:9:9:6-8:0:2; anterior genital operculum with 10-13 setae, posterior margin with 10-14 marginal setae, 22-24 in total; leg IV with a long tactile seta on both tarsal segments: basitarsus 3.56-5.00 × longer than deep (TS = 0.23-0.25), telotarsus 14.00-16.17 × longer than deep and 2.77-2.88 × longer than basitarsus (TS = 0.27-0.29).

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 2.16-2.21 (2.13-2.26). Pedipalps: trochanter 0.32-0.33/0.17-0.19 (0.32-0.34/0.18-0.20), femur 1.29-1.35/0.16 (1.34-1.37/0.16-0.17), patella 0.45-0.47/0.18-0.19 (0.49-0.52/0.18-0.20), chela 1.75-1.77/0.21-0.22 (1.77-1.84/0.21-0.22), hand 0.65-0.66/0.21-0.22 (0.65-0.68/0.21-0.22), movable chelal finger length 1.08 (1.11-1.16). Chelicera 0.72-0.73/0.29-0.30 (0.73-0.76/0.29-0.32), movable finger length 0.40 (0.40-0.41). Carapace 0.59/0.59-0.60 (0.59-0.65/0.62-0.66). Leg I: trochanter 0.21/0.13-0.14 (0.20-0.22/0.12-0.16), femur 0.75-0.77/0.09 (0.77-0.82/0.08-0.10), patella 0.40-0.41/0.08 (0.41-0.44/0.07-0.09), tibia 0.33/0.07 (0.34-0.37/0.06-0.07), tarsus 0.81/0.06 (0.79-0.82/0.06-0.07). Leg IV: trochanter 0.29-0.32/0.18 (0.28-0.30/0.15-0.18), femoropatella 1.11-1.16/0.23 (1.11-1.15/0.20-0.24), tibia 0.76/0.10 (0.77-0.81/0.10), basitarsus 0.32-0.34/0.08 (0.32-0.35/0.07-0.09), telotarsus 0.92-0.93/0.06 (0.92-0.98/0.06-0.07).

Remarks.

Tyrannochthonius calvatus sp. nov. can be easily distinguished from other Chinese cave-dwelling Tyrannochthonius species by lacking two carapaceal antero-median setae and the presence of intercalary teeth on the movable chelal finger only.

Distribution.

Known only from the unnamed cave (type locality) and Dongtianfu Cave.

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 2. Unnamed cave (type locality) and Dongtianfu Cave, habitats of Tyrannochthonius calvatus sp. nov. A unnamed cave B Dongtianfu Cave C live female of T. calvatus sp. nov. in its natural environment from Dongtianfu Cave.

Figure 3. Tyrannochthonius calvatus sp. nov. A holotype male, habitus (dorsal view) B paratype female, habitus (dorsal view). Scale bars: 0.50 mm.

Figure 4. Tyrannochthonius calvatus 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 (E); 0.20 mm (A, B); 0.10 mm (C, D, F, G).

Figure 5. Tyrannochthonius calvatus 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: 0.20 mm (A, B, E-I); 0.10 mm (C, D).