Allochthonius bainiensis, 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 bainiensis sp. nov.

Figs 1B , 2 , 3 , 4 , 5 , 6 Chinese name 白坭异伪蝎

Type material.

Holotype: China • ♀; Guizhou Province, Xishui County, Donghuang Town, Baini Village, Liangfeng Cave; 28°17.72'N, 106°16.80'E; 1308 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#2022-478 (Figs 1B , 2 ).

Diagnosis

(♀). The new species can be recognized by the following combination of characters: carapace without eyes or eyespots, posterior margin with two setae, chaetotaxy of carapace: 4-4-2-2-2, 14; cheliceral palm with four setae only; rallum with nine blades (each with fine pinnate, the basal-most blade shorter than the others); coxa I with six coxal spines (tridentate blades, each blade with a central fan-shaped spine terminally) on a tubercle; pedipalps slender, femur 9.07, chela 5.41 × longer than broad, both chelal fingers with a row of teeth (fixed chelal finger with 19 teeth; movable chelal finger with 17 teeth), slightly retrorse and pointed.

Etymology.

Named after the village of Baini, near the type locality.

Description.

Adult female (male unknown) (Figs 3 - 6 ). Color (Figs 3 , 4 ): generally pale yellow, chelicerae, pedipalps and tergites slightly darker, soft parts pale. Cephalothorax (Figs 4B, D , 5A, C ): carapace subquadrate, 0.87 × 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 5, III 5, IV 5-6; manducatory process with two acuminate distal setae, anterior seta less than 1/2 length of medial seta; coxal spines present on coxa I only, consisting of a tubercle expanded terminally into a characteristic “spray” or “fan” of six elevated processes which extend apically, subequal in length (Figs 4D , 5C ); bisetose intercoxal tubercle present between coxae III and IV (Fig. 4D ). Chelicera (Figs 4C , 5B, E ): large, approximately as long as carapace, 2.37 × longer than broad; four setae present on hand, all setae acuminate, ventrobasal seta shorter than others; movable finger with a medial seta; exterior condylar lyrifissure and exterior lyrifissure exist, palm with two extra setae (close to sub-basal seta). Cheliceral palm with moderate hispid granulation on both ventral and dorsal sides. Both fingers well provided with teeth, fixed finger with 14 acute teeth, distal one largest, plus five small basal teeth, 19 in total; movable finger with 21 retrorse contiguous teeth of equal length; galea absent. Serrula exterior with 18 blades and serrula interior with 12 blades. Rallum in two rows and composed of nine blades with fine pinnate, of which the basal-most blade shorter than the others (Fig. 5E ). Pedipalp (Figs 4A , 5D , 6A, B ): long and slender, trochanter 1.68, femur 9.07, patella 3.06, chela 5.41, hand 2.29 × longer than broad; femur 2.62 × longer than patella; movable chelal finger 1.44 × longer than hand and 0.61 × longer than chela. Setae generally long and acuminate; two distal lyrifissures present on patella (Fig. 5D ). 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; 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. 6A ). 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 19 teeth, slightly retrorse and pointed; movable chelal finger with 17 teeth (slightly smaller than teeth on fixed chelal finger) and a tubercle between the ninth and tenth teeth (Fig. 6A ). Chelal fingers slightly curved in dorsal view (Fig. 6B ). Opisthosoma: generally typical, pleural membrane finely granulated. Tergites and sternites undivided; setae uniseriate and acuminate. Tergal chaetotaxy I-XII: 2: 4: 4: 6: 6: 7: 7: 6: 7: 5: TT: 0; tergites IX and X each with an unpaired median seta. Sternal chaetotaxy IV-XII: 10: 11: 11: 11: 11: 9: 8: 0: 2. Anterior genital operculum with eight setae plus 14 setae on posterior margin, with a pair of lyrifissures present anterolateral and posteriolateral to genital opening, respectively (Fig. 4E ). Legs (Fig. 6C, D ): generally typical, long, and slender. Fine granulation present on anterodorsal faces of femur IV and patella IV. Femur of leg I 1.77 × longer than patella and with one lyrifissure at the base of femur; tarsus 2.55 × longer than tibia. Femoropatella of leg IV 4.86 × longer than deep and with one lyrifissure at the base of femur; tibia 6.17 × longer than deep; with basal tactile setae on both tarsal segments: basitarsus 4.22 × longer than deep (TS = 0.24), telotarsus 12.43 × longer than deep and 2.29 × longer than basitarsus (TS = 0.31). Setae of leg I (trochanter to tibia) 2: 10: 9: 12, setae of leg IV (trochanter to basitarsus) 3: 3: 7: 15: 17. Arolium slightly shorter than the claws, not divided; claws simple. Dimensions of female holotype (length/breadth or, in the case of the legs, length/depth in mm): body length 2.72. Pedipalps: trochanter 0.32/0.19, femur 1.36/0.15, patella 0.52/0.17, chela 1.84/0.34, hand 0.78/0.34, movable finger length 1.12. Chelicera 0.64/0.27, movable finger length 0.34. Carapace 0.55/0.63. Leg I: trochanter 0.24/0.18, femur 0.76/0.11, patella 0.43/0.10, tibia 0.33/0.07, tarsus 0.84/0.07. Leg IV: trochanter 0.34/0.18, femoropatella 1.02/0.21, tibia 0.74/0.12, basitarsus 0.38/0.09, telotarsus 0.87/0.07.

Remarks.

Allochthonius bainiensis sp. nov. is similar to A. pandus sp. nov. and A. xinqiaoensis sp. nov. in having the same number of setae on the carapace (14) and chelicera (6), while differs in the absence of a pair of curved chelal fingers (dorsal view) and the presence of lower number of teeth on chelal fingers (19 vs. 31-33 or 23 teeth on the fixed chelal finger and 17 vs. 26-28 or 23 teeth on the movable chelal finger).

Allochthonius bainiensis sp. nov. differs from A. brevitus and A. yoshizawai Viana & Ferreira, 2021 in the number of setae on the anterior of the carapace (4 vs. 6) and the cheliceral hand (5 vs. 6), and the number of rallum blades (9 vs. 11).

Allochthonius bainiensis sp. nov. can be distinguished from A. ishikawai Morikawa, 1954 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 larger body size (2.72 vs. 2.38 mm, which is the longest body length of all A. ishikawai subspecies, for example, female of A. ishikawai uyamadensis , Morikawa, 1954).

Allochthonius bainiensis 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, Liangfeng Cave (Figs 1B , 2 ), which is located near a road, 0.6 km southeast of Baini Village (Xishui County). This limestone cave has a medium-sized rectangular entrance (~ 3 m high and 5 m wide) with a large horizontally extending interior space. The interior of the cave is mainly divided into three tunnels, the left tunnel extends ~ 200 m, the middle tunnel extends ~ 500 m, and the right tunnel communicates with the middle tunnel, ~ 100 m in length. Human disturbance in the entrance zone is serious, but the deep zone remains pristine. The specimen was collected under a stone near the wall in the deepest part of the middle tunnel. This space is completely dark, with constant temperature and humidity (temperature ~ 9 °C, humidity ~ 90%).

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 2. Liangfeng Cave, type locality of Allochthonius bainiensis sp. nov. A entrance B inside the cave entrance C, D area where A. bainiensis sp. nov. specimen was collected (red arrow).

Figure 3. Allochthonius bainiensis sp. nov., holotype female, habitus (dorsal view). Scale bar: 0.50 mm.

Figure 4. Allochthonius bainiensis sp. nov., holotype female A left chela (lateral view) B carapace (dorsal view) C left chelicera (dorsal view) D coxae (ventral view) E female genital area (ventral view). Scale bars: 0.20 mm (A, D); 0.10 mm (B, C, E).

Figure 5. Allochthonius bainiensis sp. nov., holotype female 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 6. Allochthonius bainiensis sp. nov., holotype female 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.