Allochthonius pandus, Gao & Hou & Zhang, 2023

Gao, Zhizhong, Hou, Yanmeng & Zhang, Feng, 2023, Four new species of cave-adapted pseudoscorpions (Pseudoscorpiones, Pseudotyrannochthoniidae) from Guizhou, China, ZooKeys 1139, pp. 33-69 : 33

Allochthonius pandus sp. nov.

Figs 1C , 7 , 8 , 9 , 10 , 11 , 12 Chinese name 弯指异伪蝎

Type material.

Holotype: China • ♂; Guizhou Province, Xishui County, Xianyuan Town, Jinshan Village, Daozuo Cave; 28°18.04'N, 106°41.70'E; 1606 m a.s.l.; 24 Jul. 2022; Yanmeng Hou, Lu Zhang, Jianzhou Sun and Wenlong Fan leg.; under a stone in the deep zone; Ps.-MHBU-HBUARA#2022-47701 (Figs 1C , 7A-E ). Paratypes: • 1♂; the same location as the holotype; 28 Aug. 2020; Zegang Feng, Hongru Xu and Yanmeng Hou leg.; Ps.-MHBU-GZXS-20-24 • 2♀; the same data as the holotype; Ps.-MSWU-HBUARA#2022-47702-HBUARA#2022-47703.

Diagnosis

(♂♀). The new species can be recognized by the following combination of characters: cheliceral palm with five setae; coxa I with four coxal spines (tridentate blades, each blade with a central fan-shaped spine terminally) on a tubercle; pedipalps slender, femur 9.07-10.15 (♂), 8.50-8.60 (♀), chela 7.00-7.52 (♂), 6.64-7.15 (♀) × longer than broad, both chelal fingers with a row of teeth (fixed chelal finger with 31 or 33 teeth; movable chelal finger with 26 or 28 teeth), slightly retrorse and pointed; chela fingers markedly curved in dorsal view.

Etymology.

The specific name is derived from the Latin word pandus (curved) and refers to the character of the curved chelal fingers.

Description.

Adult males (Figs 7F , 8A , 9 , 10A, B , 11 , 12 ). Color (Figs 7F , 8A , 9 , 10A, B ): generally pale yellow, chelicerae, pedipalps and tergites slightly darker, soft parts pale. Cephalothorax (Figs 9B , 10A , 11A, C ): carapace inverted trapezoid, 0.91-0.93 × longer than broad, gently narrowed posteriorly; surface smooth, without furrows but with six lyrifissures and the posterior part with squamous sculpturing; no traces of eyes; epistomal process absent, space between median setae slightly recurved; with 14 setae arranged 4: 4: 2: 2: 2, preocular setae absent, most setae heavy, long, and gently curved. Chaetotaxy of coxae: P 3, I 4, II 4-6, III 5, IV 5; manducatory process with two acuminate distal setae, anterior seta less than 1/3 length of medial seta; coxal spines present on coxa I only, consisting of a tubercle expanded terminally into a characteristic “spray” or “fan” of four elevated processes which extend apically, subequal in length (Figs 10A , 11C ); bisetose intercoxal tubercle present between coxae III and IV (Fig. 10A ). Chelicera (Figs 9C , 11B, E ): large, approximately as long as carapace, 2.56-2.60 × 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 a medial seta. Cheliceral palm with moderate hispid granulation on both ventral and dorsal sides. Both fingers well provided with teeth, fixed finger with ten acute teeth, distal one largest; movable finger with 15 or 16 retrorse contiguous teeth of equal length, plus four or five vestigial, rounded, and contiguous basal teeth, 19-21 in total; galea absent. Serrula exterior with 19 or 20 blades and serrula interior with 10 or 11 blades. Rallum in two rows and composed of nine blades with fine pinnate, of which the basal-most blade shorter than the others (Fig. 11E ). Pedipalp (Figs 9A , 11D , 12A, B ): long and slender, trochanter 1.65-1.67, femur 9.07-10.15, patella 3.47-3.57, chela 7.00-7.52, hand 2.60-2.96 × longer than broad; femur 2.44-2.64 × longer than patella; movable chelal finger 1.59-1.72 × longer than hand and 0.62-0.64 × longer than chela. Setae generally long and acuminate; one distal lyrifissure present on patella (Fig. 11D ). Chelal palm slightly constricted towards fingers. Fixed chelal finger and hand with eight trichobothria, movable chelal finger with four trichobothria, ib, isb, eb, esb, and ist clustered at the base of fixed finger, esb slightly distal to ist; it slightly distal to est, situated subdistally; et situated subdistally, very close to chelal teeth; dx situated distal to et, near the tip of fixed finger; sb situated closer to b than to st (Fig. 12A ). Microsetae (chemosensory setae) absent on hand and both palpal fingers. Sensilla absent. Both chelal fingers with a row of teeth, homodentate, 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 31 or 33 teeth, slightly retrorse and pointed; movable chelal finger with 24 or 25 teeth (slightly smaller than teeth on fixed chelal finger), plus two or three vestigial, rounded and contiguous basal teeth, 26-28 in total; a small tubercle between the fourteenth and fifteenth teeth present (Fig. 12A ). Chelal fingers markedly curved in dorsal view (Fig. 12B ). Opisthosoma: generally typical, pleural membrane finely granulated. Tergites and sternites undivided; setae uniseriate and acuminate. Tergal chaetotaxy I-XII: 2: 4-5: 4-5: 6: 6: 6: 6: 6: 3: 2: TT: 0, tergite IX with an unpaired median seta. Sternal chaetotaxy III-XII: 6-8: 9-10: 9-11: 9: 9-10: 9-10: 7-8: 5-6: 0: 2. Anterior genital operculum with eight setae, genital opening pit-like, with five or six marginal setae on each side, 18-19 in total, with a pair of lyrifissures present anterolateral and posteriolateral to genital opening, respectively (Fig. 10B ). Legs (Fig. 12C, D ): generally typical, long, and slender. Fine granulation present on anterodorsal faces of femur IV and patella IV. Femur of leg I 1.64-1.79 × longer than patella and with one lyrifissure at the base of femur; tarsus 2.42-2.60 × longer than tibia. Femoropatella of leg IV 5.00-5.17 × longer than deep and with one lyrifissure at the base of femur; tibia 6.55-7.30 × longer than deep; with a long tactile seta on both tarsal segments: basitarsus 4.00-4.86 × longer than deep (TS = 0.21-0.25), telotarsus 13.50-14.50 × longer than deep and 2.38-2.72 × longer than basitarsus (TS = 0.22-0.25). Setae of leg I (trochanter to tibia) 2-3: 9-11: 9-10: 12-13, setae of leg IV (trochanter to basitarsus) 2-3: 2: 4-5: 17-19: 10-11. Arolium slightly shorter than the claws, not divided; claws simple. Dimensions of adult males (length/breadth or, in the case of the legs, length/depth in mm): body length 1.97-2.23. Pedipalps: trochanter 0.28-0.30/0.17-0.18, femur 1.27-1.32/0.13-0.14, patella 0.50-0.52/0.14-0.15, chela 1.73-1.75/0.23-0.25, hand 0.65-0.68/0.23-0.25, movable chelal finger length 1.08-1.12. Chelicera 0.64-0.65/0.25, movable finger length 0.33-0.34. Carapace 0.53-0.54/0.58. Leg I: trochanter 0.20-0.21/0.15, femur 0.68-0.69/0.08-0.09, patella 0.38-0.42/0.08, tibia 0.30-0.31/0.05-0.06, tarsus 0.75-0.78/0.05-0.06. Leg IV: trochanter 0.29-0.30/0.16-0.17, femoropatella 0.93-0.95/0.18-0.19, tibia 0.72-0.73/0.10-0.11, basitarsus 0.32-0.34/0.07-0.08, telotarsus 0.81-0.87/0.06.

Adult females (Figs 8B , 10C ). Mostly same as males, but a little larger; chaetotaxy of coxae: P 3, I 4, II 5, III 5, IV 5; tergal chaetotaxy I-XII: 2: 4: 4: 4-6: 6: 6: 6: 6: 4: 2: TT: 0; sternal chaetotaxy IV-XII: 9-10: 10-12: 9: 10-11: 10-12: 7-8: 6: 0: 2; anterior genital operculum with eight or nine setae, posterior margin with nine or ten marginal setae, 17-19 in total; leg IV with a long tactile seta on both tarsal segments: basitarsus 3.78 × longer than deep (TS = 0.24), telotarsus 12.86-14.50 × longer than deep and 2.56-2.65 × longer than basitarsus (TS = 0.20-0.23). Body length 2.10-2.41. Pedipalps: trochanter 0.33/0.19-0.20 (1.65-1.74 ×), femur 1.36-1.38/0.16 (8.50-8.63 ×), patella 0.54-0.55/0.18-0.19 (2.89-3.00 ×), chela 1.86/0.26-0.28 (6.64-7.15 ×), hand 0.72-0.75/0.26-0.28 (2.68-2.77 ×), movable chelal finger length 1.16. Chelicera 0.73-0.76/0.26-0.28 (2.71-2.81 ×), movable finger length 0.39. Carapace 0.55-0.57/0.65 (0.85-0.88 ×). Leg I: trochanter 0.19/0.17 (1.12 ×), femur 0.70-0.75/0.10-0.11 (6.82-7.00 ×), patella 0.43-0.44/0.09 (4.78-4.89 ×), tibia 0.33-0.35/0.06 (5.50-5.83 ×), tarsus 0.79-0.84/0.06 (13.17-14.00 ×). Leg IV: trochanter 0.32-0.34/0.16-0.18 (1.89-2.00 ×), femoropatella 0.92-1.02/0.19-0.22 (4.64-4.84 ×), tibia 0.67-0.73/0.10-0.11 (6.64-6.70 ×), basitarsus 0.34/0.09 (3.78 ×), telotarsus 0.87-0.90/0.06-0.07 (12.86-14.50 ×).

Remarks.

Allochthonius pandus sp. nov. is similar to A. xinqiaoensis sp. nov. in having a pair of distinctly curved chelal fingers and the same chaetotaxy of the carapace (4: 4: 2: 2: 2), but differs by the presence of lower number of blades of coxal spines (4 vs. 6), more rallum blades (9 vs. 8), more slender chela (chela 6.64-7.15 (♀) × vs. 5.44 (♀) × longer than broad), lower number of setae on the coxae (3: 4: 5: 5: 5 vs. 3: 6: 7-9: 5: 5) and more teeth on the chelal fingers (31-33 vs. 23 teeth on the fixed chelal finger and 26-28 vs. 23 teeth on the movable chelal finger); Allochthonius pandus sp. nov. can be distinguished from A. bainiensis sp. nov. by the presence of a pair of distinctly curved chelal fingers.

Allochthonius pandus sp. nov. differs from A. brevitus and A. yoshizawai in the number of setae on the anterior of the carapace (4 vs. 6), the cheliceral hand (5 vs. 6) and tergite II (4-5 vs. 6 or 2), and the number of rallum blades (9 vs. 11) and the presence of more slender pedipalps (e.g., palpal femur 9.07-10.15 (♂) × longer than broad in A. pandus sp. nov., while 4.33-4.73 (♂) and 6.50 (♂) × in A. brevitus and A. yoshizawai , respectively).

Allochthonius pandus sp. nov. can be distinguished from A. ishikawai and all A. ishikawai subspecies by the number of setae on the carapace (14 vs. 16 or more), the presence of lower number of rallum blades (9 vs. 10) and more teeth on both chelal fingers (26-28 vs. 11-17 teeth on the movable finger and 31-33 vs. 9-17 teeth on the fixed chelal finger).

Allochthonius pandus sp. nov. can be distinguished from the other species of Allochthonius by the absence of any traces of eyes ( Morikawa 1954, 1956, 1960; Hu and Zhang 2012; Viana and Ferreira 2021; WPC 2022).

Distribution and habitat.

This species is only known from the type locality, Daozuo Cave (Figs 1C , 7 ), which is located near a road, 1 km southwest of Jinshan Village (Xishui County) and is surrounded by rural and agricultural fields. This limestone cave has a large, rectangular entrance (~ 1 m high and 30 m wide) and a total length of ~ 300 m, only a narrow tunnel leads to the deepest part of the cave, which is a slightly wider, low-temperature, high-humidity, and completely lightless environment (temperature ~ 11 °C, humidity> 90%). All specimens were collected under stones in the deepest part of the cave.

Figures

Figure 1. Study area with indication of cave locations representing the type localities. Each color represents an administrative region (red: Guizhou Province; purple: Weining County; green: Xishui County; blue: Fenggang County) A Wulibei Cave (Spelaeochthonius wulibeiensis sp. nov.) B Liangfeng Cave (Allochthonius bainiensis sp. nov.) C Daozuo Cave (A. pandus sp. nov.) D Sanjie Cave (A. xinqiaoensis sp. nov.).

Figure 7. Daozuo Cave, type locality of Allochthonius pandus sp. nov. A entrance B inside the cave entrance C narrow tunnel to the deepest part of the cave (red arrow) D, E areas where A. pandus sp. nov. specimens were collected F live male of A. pandus sp. nov. in its natural environment.

Figure 8. Allochthonius pandus sp. nov. A holotype male, habitus (dorsal view) B paratype female, habitus (dorsal view). Scale bars: 0.50 mm.

Figure 9. Allochthonius pandus sp. nov., holotype male A left chela (lateral view) B carapace (dorsal view) C left chelicera (dorsal view). Scale bars: 0.20 mm (A); 0.10 mm (B, C).

Figure 10. Allochthonius pandus sp. nov., holotype male (A, B), paratype female (C) A coxae (ventral view) B male genital area (ventral view) C female genital area (ventral view). Scale bars: 0.20 mm (A); 0.10 mm (B, C).

Figure 11. Allochthonius pandus sp. nov., holotype male A carapace (dorsal view) B left chelicera (dorsal view), with details of teeth C coxal spines on coxae I (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 12. Allochthonius pandus sp. nov., holotype male A left chela (lateral view), with details of teeth and trichobothrial pattern B left chela (dorsal view) C leg I (lateral view) D leg IV (lateral view). Scale bars: 0.20 mm.