Spelaeochthonius wulibeiensis, 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

Spelaeochthonius wulibeiensis sp. nov.

Figs 1A , 18 , 19 , 20 , 21 , 22 , 23 Chinese name 五里碑穴伪蝎

Type material.

Holotype: China • ♂; Guizhou Province, Weining County, Yancang Town, Yangguan Village, Wulibei Cave; 26°53.82'N, 104°19.36'E; 2425 m a.s.l.; 07 Aug. 2019; Zegang Feng, Zhaoyi Li and Chen Zhang leg.; under a stone in the deep zone; Ps.-MHBU-GZC19080701 (Figs 1A , 18 ). Paratypes: • 2♂; the same data as the holotype; Ps.-MHBU-GZC19080702-GZC19080703 • 1♀; the same location as the holotype; 19 May. 2017, Zhisheng Zhang, Huiming Chen and Luyu Wang leg.; Ps.-MSWU-CZCH-17-06.

Diagnosis

(♂♀). The new species can be recognized by the following combination of characters: surfaces mostly with fine reticulations; carapace without eyes or eyespots but eye region bulging and convex in dorsal view; anterior margin without protuberances; cheliceral palm with five setae; rallum with 11 blades (each with fine pinnate, the basal-most blade shorter than the others); coxal spines present on coxa I only, comprising a transverse, contiguous series of seven or eight tridentate blades, which arise from a lightly sclerotized or translucent hillock, the central ramus of each blade (except the basal two) sharply acumino-spatulate and extending beyond the lateral rami; pedipalps slender, femur 7.24 (♂), 6.40 (♀), chela 6.21-6.22 (♂), 5.68 (♀) × longer than broad, both chelal fingers with a row of teeth (fixed chelal finger with 22 or 24 teeth; movable chelal finger with 16-19 teeth), slightly retrorse and pointed; chela fingers straight in dorsal view.

Etymology.

Named after the type locality, Wulibei Cave.

Description.

Adult males (Figs 18D , 19A , 20 , 21A, B , 22 , 23 ). Color (Figs 18D , 19A , 20 , 21A, B ): generally pale yellow, chelicerae, pedipalps and tergites slightly darker, soft parts pale. Cephalothorax (Figs 20B , 21A , 22A, C ): carapace subquadrate, 1.02-1.03 × longer than broad, gently narrowed posteriorly; surface mostly with fine reticulations, without furrows but with seven or eight lyrifissures; no traces of eyes but eye region bulging and convex in dorsal view; epistome present and with some tiny spinules; with 16 setae arranged s4s: 4: 2: 2: 2, most setae heavy, long, and gently curved. Chaetotaxy of coxae: P 3, I 6-7, II 4-5, III 4, IV 4; manducatory process with two acuminate distal setae, anterior seta less than 1/2 length of medial seta; coxal spines present on coxa I only, comprising a transverse, contiguous series of seven or eight tridentate blades, which arise from a lightly sclerotized or translucent hillock, the central ramus of each blade (except the basal two) sharply acumino-spatulate and extending beyond the lateral rami (Figs 21A , 22C ); bisetose intercoxal tubercle present between coxae III and IV, tear drop-shaped (Fig. 21A ). Chelicera (Figs 20C , 22B, E ): large, approximately as long as carapace, 2.37-2.41 × longer than broad; five setae present on hand, movable finger with a medial seta, all setae acuminate, ventrobasal seta shorter than others; exterior condylar lyrifissure and exterior lyrifissure exist, palm with one extra (between sub-basal seta and an accessory seta). Cheliceral palm with moderate hispid granulation on both ventral and dorsal sides. Both fingers well provided with teeth, fixed finger with 13-15 acute teeth, distal one largest; movable finger with 12 retrorse contiguous teeth of equal length, plus three or four round proximal teeth, 15 or 16 in total; galea represented by a very slight bump on movable finger. Serrula exterior with 21 blades and serrula interior with 17-20 blades. Rallum in two rows and composed of 11 blades with fine pinnate, of which the basal-most blade shorter than the others (Fig. 22E ). Pedipalp (Figs 20A , 22D , 23A, B ): surfaces mostly with fine reticulations; long and slender, trochanter 1.78-2.00, femur 7.24, patella 2.44-2.47, chela 6.21-6.22, hand 2.26-2.36 × longer than broad; femur 2.62-2.80 × longer than patella; movable chelal finger 1.61-1.74 × longer than hand and 0.61-0.63 × longer than chela. Setae generally long and acuminate; one distal lyrifissure present on patella and femur, respectively (Fig. 22D ). Chelal palm robust and 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, ist slightly distal to esb, esb close to ist than to eb; it slightly distal to est, situated subdistally and forming a pair; et situated subdistally, very close to chelal teeth; dx situated distal to et, near the tip of fixed finger; sb distinctly closer to b than to st (Fig. 23A ). 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 22-24 teeth, slightly retrorse and pointed; movable chelal finger with 16-19 teeth (slightly smaller than teeth on fixed chelal finger); a small tubercle between the seventh and eighth teeth present (near trichobothrium t) (Fig. 23A ). Chelal fingers straight in dorsal view (Fig. 23B ). Opisthosoma: generally typical, ovate, pleural membrane finely granulated. Tergites and sternites undivided; setae uniseriate and acuminate. Tergal chaetotaxy I-XII: 2: 4: 6: 6: 6: 7-8: 8: 7: 6: 4: TT: 0, tergites VII-IX each with an unpaired median seta, one lyrifissure present on each side of tergites IV-IX. Sternal chaetotaxy III-XII: 6-9: 10-14: 13-14: 12: 12-13: 12-13: 10-11: 8-9: 0: 2, one lyrifissure present on each side of tergite III. Anterior genital operculum with 10-12 setae, genital opening pit-like, with seven marginal setae on each side, 24-26 in total, with a pair of lyrifissures present anterolateral and posteriolateral to genital opening, respectively (Fig. 21B ). Legs (Fig. 23C, D ): generally typical, long, and slender. Fine granulation present on anterodorsal faces of femur IV and patella IV. Femur of leg I 1.74 × longer than patella and with one lyrifissure at the base of femur; tarsus 2.11-2.26 × longer than tibia. Femoropatella of leg IV 3.70-3.88 × longer than deep and with one lyrifissure at the base of femur; tibia 5.92-6.00 × longer than deep; with a long tactile seta on both tarsal segments: basitarsus 4.00 × longer than deep (TS = 0.22-0.28), telotarsus 11.13-12.43 × longer than deep and 2.42-2.47 × longer than basitarsus (TS = 0.26-0.27). Setae of leg I (trochanter to tibia) 1: 13: 12-15: 14-17, setae of leg IV (trochanter to basitarsus) 2: 2: 6: 16: 14. 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). Males: body length 2.50. Pedipalps: trochanter 0.32/0.16-0.18, femur 1.23/0.17, patella 0.44-0.47/0.18-0.19, chela 1.68-1.74/0.27-0.28, hand 0.61-0.66/0.27-0.28, movable finger length 1.06. Chelicera 0.64-0.65/0.27, movable finger length 0.34. Carapace 0.63/0.61-0.62. Leg I: trochanter 0.24-0.25/0.18, femur 0.73-0.75/0.10, patella 0.42-0.43/0.09, tibia 0.34-0.37/0.07, tarsus 0.77-0.78/0.06-0.07. Leg IV: trochanter 0.33-0.36/0.19-0.22, femoropatella 0.97-1.00/0.25-0.27, tibia 0.77-0.78/0.13, basitarsus 0.36/0.09, telotarsus 0.87-0.89/0.07-0.08.

Adult female (Figs 19B , 21C ). Mostly same as males; tergal chaetotaxy I-XII: 2: 4: 6: 6: 6: 7: 8: 9: 7: 4: TT: 0; sternal chaetotaxy IV-XII: 10: 13: 11: 12: 12: 11: 8: 0: 2; anterior genital operculum with seven setae, posterior margin with 11 marginal setae, 18 in total; leg IV with a long tactile seta on both tarsal segments: basitarsus 3.60 × longer than deep (TS = 0.25), telotarsus 11.63 × longer than deep and 2.58 × longer than basitarsus (TS = 0.24). Body length 1.93. Pedipalps: trochanter 0.32/0.19 (1.68 ×), femur 1.28/0.20 (6.40 ×), patella 0.51/0.21 (2.43 ×), chela 1.76/0.31 (5.68 ×), hand 0.66/0.31 (2.13 ×), movable chelal finger length 1.11. Chelicera 0.70/0.30 (2.33 ×), movable finger length 0.38. Carapace 0.68/0.68 (1.00 ×). Leg I: trochanter 0.24/0.19 (1.26 ×), femur 0.77/0.12 (6.42 ×), patella 0.45/0.11 (4.09 ×), tibia 0.36/0.08 (4.50 ×), tarsus 0.83/0.08 (10.38 ×). Leg IV: trochanter 0.35/0.22 (1.59 ×), femoropatella 1.05/0.27 (3.89 ×), tibia 0.80/0.14 (5.71 ×), basitarsus 0.36/0.10 (3.60 ×), telotarsus 0.93/0.08 (11.63 ×).

Remarks.

The new species shares similar characters with most species of Centrochthonius Beier, 1931, Spelaeochthonius and all species of " Pseudotyrannochthonius " Beier, 1930 from the western US by the presence of only 16 setae on the carapace. Schwarze et al. (2021) emphasized the importance of the number of carapaceal setae in Holarctic pseudotyrannochthoniids, thus, it indicates that the three " Pseudotyrannochthonius " species in the western US were misclassified in comparison with the twelve species from Australia and the three species from Chile (including the type species, the number of carapaceal setae is more than 18). It can be said that the genus Pseudotyrannochthonius is endemic to the southern hemisphere ( Harvey and Harms 2022). Thus, it is inappropriate to place this new species in Pseudotyrannochthonius , even though the shape of this new species of coxal spines is similar to that of the three " Pseudotyrannochthonius " species.

The shape and number of the coxal spines are important distinguishing features between Centrochthonius and Spelaeochthonius ( You et al. 2022). In our opinion, it is appropriate to place this new species to Spelaeochthonius rather than Centrochthonius , the reasons are as follows: for Centrochthonius , the number of carapaceal setae is not fixed (e.g., occasionally 18 are present in C. anatonus Harvey & Harms, 2022) and only four or five coxal spines blades; for Spelaeochthonius , the character of coxal spines is diverse (e.g., in S. undecimclavatus Morikawa, 1956, which is club-shaped, not distally plumose).

Spelaeochthonius wulibeiensis sp. nov. is similar to S. cheonsooi You, Yoo, Harvey & Harms, 2022, but differs by the number of setae on tergite I (2 vs. 4) and larger body size (body length 1.93 (♀) mm vs. 1.70 (♀) mm; chela 5.68 (♀) × vs. 5.32 (♀) × longer than board, length 1.76 (♀) mm vs. 1.49 (♀) mm).

Spelaeochthonius wulibeiensis sp. nov. can be distinguished from S. seungsookae You, Yoo, Harvey & Harms, 2022 by the number of setae on tergite I (2 vs. 4) and smaller body size (body length 1.93 (♀) mm vs. 2.05-2.36 (♀) mm; chela length 1.68-1.74 (♂), 1.76 (♀) mm vs. 1.90 (♂), 1.92 (♀) mm); from S. undecimclavatus and S. dorogawaensis by the number of setae on chelicera (6 vs. 7), a slender palp (palpal femur 7.24 (♂) × vs. 4.80-5.40 (♂) × longer than board; chela 6.21-6.22 (♂) × vs. 5.50-6.13 (♂) × longer than board) and lower number of blades of coxal spines (7-8 vs. 10-11); from S. akiyoshiensis Morikawa, 1956 and S. kobayashii Morikawa, 1956 by the number of setae on chelicera (6 vs. 7), lower number of movable chelal finger teeth (16-19 teeth vs. min. 26 teeth) and a slender palp (palpal femur 7.24 (♂) × vs. 5.00-5.60 (♂) × longer than board; chela 6.21-6.22 (♂) × vs. 5.13-5.74 (♂) × longer than board); from S. dentifer (Morikawa, 1970) by the number of setae on chelicera (6 vs. 7), lower number of movable chelal finger teeth (16-19 teeth vs. min. 36 teeth) and a shorter chela (chela 6.21-6.22 (♂), 5.68 (♀) × vs. 6.85 (♂), 7.12 (♀) × longer than board, length 1.68-1.74 (♂), 1.76 (♀) mm vs. 1.85 (♂♀) mm); from S. kubotai by the slightly smaller body size (body length 1.93 (♀) mm vs. 2.03 (♀) mm; chela 5.68 (♀) × vs. 5.70 (♀) × longer than board; movable chelal finger 1.68 (♀) × vs. 1.87 (♀) × longer than) and the number of setae of coxal spines (7 or 8 vs. 11); from S. kishidai (Morikawa, 1960) by a slender palp (palpal femur 7.24 × vs. 4.90 × longer than board; movable chelal finger 0.61-0.63 × vs. 0.67-0.69 × longer than board) ( Morikawa 1954, 1956, 1960, 1970; You et al. 2022).

Distribution and habitat.

This species is known only from the type locality, Wulibei Cave (Figs 1A , 18A-C ), which is located ~ 1.2 km east of Yangguan Village (Weining County). This limestone cave has an elongated entrance (~ 2.5 m high and 8 m wide) with some corn stalks scattered nearby. Entrance of the cave has a large muddy cave hall, connected to a small hall through a narrow tunnel, which is a more enclosed, completely dark space, covered with gravel, with temperatures ~ 10 °C and humidity ~ 90%. The specimen was collected under a stone in a small cave hall.

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 18. Wulibei Cave, type locality of Spelaeochthonius wulibeiensis sp. nov. A cave location (red arrow) B entrance C inside the cave entrance D live male of S. wulibeiensis sp. nov. in its natural environment.

Figure 19. Spelaeochthonius wulibeiensis sp. nov. A holotype male, habitus (minus left chelicera, pedipalp, legs I and IV, dorsal view) B paratype female, habitus (dorsal view). Scale bars: 0.50 mm.

Figure 20. Spelaeochthonius wulibeiensis 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 21. Spelaeochthonius wulibeiensis 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 22. Spelaeochthonius wulibeiensis sp. nov., holotype male A carapace (dorsal view), with a detail of anterior margin 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 23. Spelaeochthonius wulibeiensis 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.