Metachelifer mahnerti, Li & Shi, 2022

Li, Yun-Chun & Shi, Ai-Min, 2022, Cave-inhabiting Cheliferidae (Arachnida, Pseudoscorpiones) from Thailand, with description of four new species of Metachelifer Redikorzev, ZooKeys 1103, pp. 171-188 : 171

Metachelifer mahnerti sp. nov.

Figs 2 , 5C, D

Type material.

Holotype male: Thailand, Chiangmai Province, Chom Thong district, Ban Luang Village, Tham Borichinda Cave, 18°29'53.01"N, 98°40'49.97"E, 379 m a.s.l., 15 Oct. 2014, Yun-Chun Li and Zhi-Gang Chen leg., in MCWNU (Ms20141015-01). Paratypes: 1 male, 7 females, 1 tritonymph, collected with the holotype in MCWNU (Ms20141015-01); 1 male, 1 female, collected with the holotype, in MNHN.

Diagnosis.

Troglobiont habitus. This new species is distinguished from other members of the genus Metachelifer by the following combination of characters: anterior margin of carapace with 4 denticuloclavate setae and 91-93 setae; tergite XI without tactile setae; male anterior genital operculum with 68-70 setae (11-16 of them tubular); female anterior genital operculum without tubular setae, posterior operculum with 8 lyrifissures; and female body very large, 4.76-4.85 mm.

Etymology.

The new species is named in honour of the late Volker Mahnert ( Muséum d’histoire naturelle, Genève, Switzerland).

Description.

Adult male (Fig. 5C ). Carapace, pedipalps and tergites I-V dark brown, remaining parts yellowish brown (Fig. 5C ).

Carapace (Fig. 2A ): 1.05-1.06 × longer than broad, with a pair of well-developed eyes, length of eyes 0.10 mm, breadth 0.04 mm, carapace surface evenly and strongly granular. Median and posterior furrows prominent, regularly granular. Dorsal setae of carapace, borne on larger but relatively inconspicuous tubercles. With 91-93 denticuloclavate setae, including 4 on anterior margin and 13-14 on posterior margin. Coxae: manducatory process with 4 setae (1 long apical, 2 rather short subapical setae, and 1 suboral seta at base of medial margin). Pedipalpal coxa with 11-12 (non-denticulate) + 4-5 (denticulate) setae, coxa I 20-22, II 19-21, III 21-23, IV with an anterolateral process and 43-47 setae. Coxal sac occupying only 2/5 of coxal length, atrium well developed (Fig. 2E ). Chelicera (Fig. 2B, C ): 1.66-1.69 × longer than broad, hand with 5 setae and 1 lyrifissure dorsally, movable finger with 1 submedial seta and 3 teeth (Fig. 2B ). Galea with 3 short branches. Serrula exterior with about 19-20 blades. Rallum with 3 blades, anterior 1 weakly denticulate distally (Fig. 2C ). Pedipalp (Fig. 2F-H ): all segments with well-developed granulations, except for chelal fingers, which are smooth; dorsal setae short and prominently denticuloclavate. Trochanter 1.97-1.99 × longer than broad, femur 6.86-6.90 × longer than broad, patella 4.89-4.91 × longer than broad, femur 1.14-1.15 × longer than patella. Chela with pedicel 6.11-6.14 × longer than broad, hand with pedicel 2.97-2.99 × longer than broad; movable finger 1.06-1.07 × longer than hand with pedicel length. Fixed finger with 58-60 small cusped teeth, movable finger with 57-60 teeth; venom apparatus present in both chelal fingers, very short (Fig. 2H ). Fixed chelal finger with 8 trichobothria and movable finger with 4, eb - esb (retrolateral view) and ib-isb (dorsal view) at the base of the fixed finger; est in finger middle, et distinctly closer to fingertip than to it; on movable finger, st nearer to sb than to t. Opisthosoma: tergal chaetotaxy (I-XI): 14: 16: 16: 18: 20: 24: 23: 20: 20: 13: 14; sternal chaetotaxy (IV-XI): 2 × 1 + 10: 12: 14: 12: 14: 13: 15: 13; anal cone with 2 dorsal and 2 ventral setae. Tergite XI without tactile setae. Because only two specimens were available for the study, the structure of the genitalia could not be examined in detail. Anterior genital operculum with 68-70 setae (11-16 of them tubular) and 2 lyrifissures; posterior operculum with 17-19 setae, 8 lyrifissures (Fig. 2I ). Legs: Leg I: surface with weak scale-like sculpture, trochanter 1.35-1.36 ×, femur 1.84-1.86 × longer than deep and 0.58-0.60 × longer than patella; patella 4.00-4.02 ×, tibia 5.00-5.03 ×, tarsus 6.11-6.14 × longer than deep, subterminal seta simple, claws modified and asymmetrical, lateral claw shorter than mesal one (Fig. 2D ). Leg IV: trochanter 1.63-1. 64 × longer than deep, femoropatella 3.93-3.96 ×, tibia 7.38-7.40 × longer than deep and tarsus 7.22-7.26 × longer than deep. Arolia on legs I and IV shorter than claws.

Adult female (Fig. 5 D ). Mostly the same as the holotype.

Carapace: slightly longer than broad (1.00-1.01 ×), anterior margin with 4 setae, posterior margin with 12-13 setae. Well-developed paramedian impressions behind eyes like in male. Coxae: pedipalpal coxa with 9 (non-denticulate) + 4-6 (denticulate) setae, coxa I 20-21, II 18, III 17-19, IV 52-55. Chelicera: 1.94-1.97 × longer than broad, movable finger with 2-3 teeth. Pedipalp: trochanter 2.03-2.05 × longer than broad, femur 6.18-6.21 × longer than broad, patella 4.81-4.86 × longer than broad, femur 1.16-1.17 × longer than patella. Chela with pedicel 5.10-5.11 × longer than broad, hand with pedicel 2.51-2.53 × longer than broad; movable finger 1.01-1.02 × longer than hand with pedicel length. Opisthosoma: tergal chaetotaxy (I-XI): 15: 18: 20: 24: 23: 25: 25: 26: 23: 16: 15; sternal chaetotaxy (IV-XI): 2 × 1 + 11: 15: 15: 15: 13: 14: 13: 10; anal cone with 2 dorsal and 2 ventral setae. Anterior genital operculum with 28 setae (without tubular setae) and 2 lyrifissures; posterior operculum with 13 setae, 8 lyrifissures (Fig. 2J ). Sternites with 2 lateral cribriform plates.

Dimensions

(length/width or, in the case of the legs, length/depth in mm). Males (females in parentheses): body length 3.23-3.35 (4.76-4.85). Carapace 1.05-1.06/1.00-1.01 (1.21-1.23/1.21-1.22). Pedipalp: trochanter 0.59-0.61/0.30-0.31 (0.67-0.69/0.33-0.35), femur 1.51-1.53/0.22-0.24 (1.73-1.75/0.28-0.29), patella 1.32-1.34/0.27-0.29 (1.49-1.51/0.31-0.33), hand with pedicel 1.04-1.05/0.35-0.37 (1.23-1.25/0.49-0.51), length of movable chelal finger 1.10-1.11 (1.24-1.26), length of chela 2.14-2.15/0.35-0.37 (2.50-2.53/0.49-0.51). Chelicera: 0.26-0.27/0.14-0.15 (0.28-0.30/0.14-0.15). Leg I: trochanter 0.23-0.25/0.17-0.18 (0.31-0.33/0.22-0.23), femur 0.35-0.37/0.19-0.20 (0.30-0.32/0.21-0.23), patella 0.60-0.61/0.15-0.16 (0.76-0.79/0.16-0.17), tibia 0.60-0.62/0.12-0.13 (0.73-0.75/0.11-0.12), tarsus 0.55-0.56/0.09-0.10 (0.70-0.71/0.10-0.11). Leg IV: trochanter 0.31-0.33/0.19-0.21 (0.39-0.41/0.25-0.26), femoropatella 1.06-1.08/0.27-0.28 (1.18-1.20/0.32-0.33), tibia 0.96-0.97/0.13-0.14 (1.15-1.16/0.14-0.15), tarsus 0.65-0.67/0.09-0.10 (0.78-0.80/0.10-0.11).

Distribution.

Thailand (Chiangmai).

Figures

Figure 2. Metachelifer mahnerti sp. nov., holotype male (A-I) and paratype female (J) A carapace B left chelicera C rallum of left chelicera D detail on tarsus I, lateral view E coxa IV, ventral view F palp (minus chela) G chela, retrolateral view H chela, dorsal view I male genital area J female genital area. Scale bars: 0.50 mm.

Figure 5. A, B Metachelifer cheni sp. nov., dorsal views A holotype male B paratype female C, D M. mahnerti sp. nov., dorsal views C holotype male D paratype female. Scale bar: 1.00 mm (A-D).