Metachelifer cheni, 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 cheni sp. nov.

Figs 1 , 5A, B

Type material.

Holotype male: Thailand, Nakhon Ratchasima Province, Pak Chong district, Musee Village, Wat Dewaroop Song Cave 3, 14°33.714'N, 101°24.049'E, 402 m a.s.l., 24 Oct. 2014, Yun-Chun Li and Zhi-Gang Chen leg., in MCWNU (Ms20141014-01). Paratypes: 3 males, 7 females, 7 tritonymphs, collected with the holotype, in MCWNU (Ms20141014-01); 1 male, 2 females, 1 tritonymph, 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: carapace with 100-101 setae; coxal sac occupying 1/2 of coxal length; male anterior genital operculum without tubular setae; female anterior genital operculum with 31 setae (24 of them tubular) and two lyrifissures; posterior operculum with 12 setae, without lyrifissures.

Etymology.

Latinized adjective, derived from the last name of the collector, Zhi-Gang Chen.

Description.

Adult male (Fig. 5A ). Carapace, pedipalps and tergites I-III brown, remaining parts yellowish brown (Fig. 5A ).

Carapace (Fig. 1A ): 1.14-1.16 × longer than broad, with a pair of well-developed eyes, length of eyes 0.09 mm, breadth 0.03 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 100-101 denticuloclavate setae, including 8 on anterior margin and 11-12 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 10 (non-denticulate) + 7-8 (denticulate) setae, coxa I 14-16, II 15, III 18-19, IV with an anterolateral process and 30-36 setae. Coxal sac occupying only 1/2 of coxal length, atrium well developed (Fig. 1E ). Chelicera (Fig. 1B ): 1.85-1.91 × longer than broad, hand with 5 setae and 1 lyrifissure dorsally, movable finger with 1 submedial seta (1 specimen with 2 submedial setae) and 2-3 teeth (Fig. 1B ). Galea with a short, broad stump on left chelicera (clearly broken). Serrula exterior with about 21-22 blades. Rallum with 3 blades, anterior 1 weakly denticulate distally. Pedipalp (Fig. 1F-H ): all segments with well-developed granulations, except for chelal fingers, which are smooth; dorsal setae short and prominently denticuloclavate. Trochanter 1.92-1.95 ×, femur 6.55-6.57 ×, patella 5.29-5.33 × longer than broad. Femur 1.13-1.14 × longer than patella. Chela with pedicel 6.10-6.12 ×, hand with pedicel 3.06-3.08 × longer than broad; movable chelal finger 1.03-1.04 × longer than hand with pedicel length. Fixed finger with 64-66 small cusped teeth, movable finger with 63-65 teeth; venom apparatus present in both chelal fingers very short (Fig. 1G ). 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): 10: 12: 13: 14: 16: 16: 14: 19: 19: 15: 12; sternal chaetotaxy (IV-XI): 2 × 2 + 9: 11: 12: 12: 10: 14: 10: 9; anal cone with 2 dorsal and 2 ventral setae. Tergite XI with 2 tactile setae. Anterior genital operculum with 73-74 setae and 2 lyrifissures; posterior operculum with 16-17 setae, 7-8 lyrifissures (Fig. 1I ). Structure of male genitalia as illustrated (Fig. 1J ); eversible sacs large; apodeme of eversible sac and lateral apodeme well developed. Legs (Figs 1C-D ): Leg I: surface with weak scale-like sculpture, trochanter 1.24-1.25 ×, femur 1.76-1.78 × longer than deep and 0.51-0.53 × longer than patella; patella 4.21-4.24 ×, tibia 5.90-5.93 ×, tarsus 5.11-5.16 × longer than deep, subterminal seta simple, claws modified and asymmetrical, lateral claw shorter than mesal one (Fig. 1C ). Leg IV: trochanter 1.94-1.95 ×, femoropatella 4.91-4.95 ×, tibia 9.20-9.23 × longer than deep and tarsus 8.00-8.05 × longer than deep. Arolia on legs I and IV shorter than claws (Fig. 1C, D ).

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

Carapace: slightly longer than broad (1.12-1.13 ×), anterior margin with 6 setae, posterior margin with 12-13 setae. Well-developed paramedian impressions behind eyes as in male. Coxae: pedipalpal coxa with 14 setae, coxa I 12-15, II 19-21, III 22-25, IV 33-38. Chelicera: 1.98-2.01 × longer than broad, movable finger with 3 teeth. Pedipalp: trochanter 2.07-2.09 × longer than broad, femur 6.46-6.48 × longer than broad, patella 5.11-5.15 × longer than broad, femur 1.12-1.13 × longer than patella. Chela with pedicel 5.53-5.56 × longer than broad, hand with pedicel 2.82-2.84 × longer than broad; movable finger 1.02-1.03 × longer than hand with pedicel length. Opisthosoma: tergal chaetotaxy (I-XI): 11: 14: 13: 14: 16: 18: 18: 18: 18: 16: 9; sternal chaetotaxy (IV-XI): 2 × 1 + 9: 15: 12: 13: 11: 14: 14: 7; anal cone with 2 dorsal and 2 ventral setae. Anterior genital operculum with 31 setae (24 of them tubular) and 2 lyrifissures; posterior operculum with 12 setae, without lyrifissures (Fig. 1K ). 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 2.52-2.74 (3.70-3.92). Carapace 0.96-0.98/0.84-0.86 (1.05-1.09/0.94-0.96). Pedipalp: trochanter 0.50-0.52/0.26-0.27 (0.58-0.60/0.28-0.29), femur 1.44-1.46/0.22-0.23 (1.55-1.58/0.24-0.25), patella 1.27-1.29/0.24-0.25 (1.38-1.41/0.27-0.28), hand with pedicel 0.95-0.97/0.31-0.32 (1.07-1.10/0.38-0.39), length of movable chelal finger 0.98-0.99 (1.09-1.11), chela 1.89-1.93/0.31-0.32 (2.10-2.13/0.38-0.39). Chelicera: 0.24-0.26/0.13-0.14 (0.26-0.28/0.14-0.15). Leg I: trochanter 0.21-0.22/0.17-0.18 (0.25-0.26/0.18-0.19), femur 0.30-0.32/0.17-0.18 (0.35-0.37/0.17-0.18), patella 0.59-0.61/0.14-0.15 (0.61-0.65/0.15-0.16), tibia 0.59-0.60/0.10-0.11 (0.65-0.66/0.10-0.11), tarsus 0.46-0.49/0.09-0.10 (0.65-0.67/0.10-0.11). Leg IV: trochanter 0.33-0.34/0.17-0.18 (0.35-0.37/0.23-0.24), femoropatella 1.08-1.10/0.22-0.23 (1.06-1.09/0.25-0.26), tibia 0.92-0.95/0.10-0.11 (0.98-0.99/0.12-0.13), tarsus 0.64-0.65/0.08-0.09 (0.65-0.68/0.09-0.10).

Distribution.

Thailand (Nakhon Ratchasima).

Figures

Figure 1. Metachelifer cheni sp. nov., holotype male (A-J) and paratype female (K) A carapace B left chelicera C right leg I, lateral view D right leg IV, lateral view E coxa IV, ventral view F palp (minus chela) G chela, retrolateral view H chela, dorsal view I male genital area J male genitalia, dorsal view K 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).