Tyrannochthonius yamuhensis, Li, 2022

Li, Yun-Chun, 2022, Five new troglobitic species of Tyrannochthonius (Arachnida, Pseudoscorpiones, Chthoniidae) from the Yunnan, Guizhou and Sichuan Provinces, China, ZooKeys 1131, pp. 173-195 : 173

Tyrannochthonius yamuhensis sp. nov.

Figs 5 , 8A

Type material.

Holotype male: China, Yunnan Province, Lushui City, Fugong County, Shiyueliang Town, Lishadi Village, Yamu River, Nameless Cave, 27°07.69'N, 98°51.61'E, 1500 m a.s.l., 18 August 2018, Yun-Chun Li leg., in MCWNU (Ar-Ps-YN-0078). Paratypes: 1 male, collected with the holotype, in MCWNU (Ar-Ps-YN-0014).

Diagnosis

(male, female unknown). Troglobiont habitus. This new species is distinguished from other members of the genus Tyrannochthonius by the following combination of characters: carapace without eyes or eyespots, anterior margin with four setae; epistome present; tergites II-VI with four setae; coxae II with ten terminally indented coxal spines on each side; apex of coxa I with long and rounded anteromedial process, near the apex with a seta; chelal hand dorsal surface with chemosensory setae. Fixed chelal finger with 25 teeth and 20 intercalary teeth, movable chelal finger with 22-24 teeth and three or four intercalary teeth. Pedipalpal femur 6.06-6.07 × longer than broad, length 0.97-0.99 mm; chela 7.63-7.66 × longer than deep, length 1.45-1.46 mm; ratio movable chelal finger/chelal hand 1.91-1.92 ×.

Etymology.

Latinized adjective, derived from the river of Yamuhe, which is near the type locality.

Description.

Adult male (Fig. 8 ).

Chelicera reddish brown, carapace and opisthosoma brown, remaining parts yellowish brown (Fig. 8 ).

Carapace (Fig. 5A ): 1.06-1.08 × longer than broad, no eyes or eyespots; epistome very pointed and small, triangular; carapace surface smooth, lateral margins weakly constricted posteriorly. With 18 setae, including four on anterior margin and two on posterior margin, anterolateral setae much shorter than others. Coxae: manducatory process pointed, with two distal setae, one long and the other slightly shorter. Pedipalpal coxa with three setae, coxa I 3, II 4, III 5, IV 5; intercoxal tubercle absent. Apex of coxa I with long and rounded anteromedial process, near the apex with a seta; coxae II with ten terminally indented coxal spines on each side, set as an oblique row, longer spines present in the middle of the row, becoming shorter distally and proximally and incised for ~ ½ their length (Fig. 5D ). Chelicera (Fig. 5B ): 2.31-2.33 × longer than broad, hand with five setae and two lyrifissures dorsally, movable finger with one submedial seta. Cheliceral hand with moderate hispid granulation dorsally. Fixed finger with eight or nine teeth, distal one largest, decreasing in size proximally; movable finger with 12 or 13 teeth; galea absent. Serrula exterior with 20 or 21 blades. Rallum composed of eight blades (Fig. 5C ), distal blade weakly recumbent basally, with fine barbules and set apart from the other blades, the latter tightly grouped and with long pinnae. Pedipalp (Fig. 5F-H ): all setae acuminate. Trochanter 1.01-1.04 ×, femur 6.06-6.07 ×, patella 2.38-2.40 × longer than broad. Femur 2.55-2.56 × longer than patella. Chela 7.63-7.66 ×, hand 2.47-2.50 × longer than deep; movable chelal finger 1.91-1.92 × longer than hand. Chelal hand dorsal surface with a single row of five chemosensory setae between esb and ib / isb trichobothria; distal paraxial seta of hand not enlarged. Fingers straight in dorsal view (Fig. 5H ). Fixed finger with 25 teeth and 20 intercalary teeth, middle ones larger than those at both ends; movable finger with 22-24 teeth and three or four intercalary teeth (Fig. 5G ). Venom apparatus absent. Fixed chelal finger with eight trichobothria and movable finger with four, ib and isb situated close together, submedially on dorsum of chelal hand; eb, esb, and ist forming a straight oblique row at base of fixed chelal finger; it slightly distal to est, situated subdistally; et slightly nearer to tip of fixed finger; dx situated distal to et; sb near to st; b and t situated subdistally, t situated at same level as est. Opisthosoma: tergites and sternites undivided; setae uniseriate and acuminate. Tergal chaetotaxy (I-XII): 3: 4: 4: 4: 4: 4: 6: 5: 5: 5: 2: 0; sternal chaetotaxy (IV-XII): 12: 10: 7: 7: 7: 7: 6: 0: 2. Anterior genital operculum with ten, genital opening slit-like, with 15 or 16 marginal setae on each side (Fig. 5I ). Legs: leg I: trochanter 1.38-1.40 ×, femur 6.63-6.65 × longer than deep and 1.77-1.79 × longer than patella; patella 4.29-4.30 ×, tibia 5.20-5.22 ×, tarsus 11.80-11.81 × longer than deep. Leg IV: trochanter 1.06-1.07 ×, femoropatella 3.00-3.02 ×, tibia 5.70-5.71 × longer than deep, basitarsus 3.00-3.01 × longer than deep, with a basal tactile seta (TS = 0.20-0.21), telotarsus 12.80-12.81 × longer than deep and 2.67-2.69 × longer than basitarsus, with a tactile seta near base (TS = 0.19-0.20). Arolia on legs I and IV shorter than claws.

Dimensions (mm, length/width or, in the case of the legs, chela, and chelal hand, length/depth).

Males: body length 2.25-2.30. Carapace 0.56-0.57/0.53-0.54. Pedipalp: trochanter 0.14-0.15/0.14-0.15, femur 0.97-0.99/0.16-0.18, patella 0.38-0.39/0.16-0.17, hand 0.47-0.49/0.19-0.20, length of movable chelal finger 0.90-0.92, chela 1.45-1.46/0.19-0.20. Leg I: trochanter 0.18-0.19/0.13-0.15, femur 0.53-0.55/0.08-0.09, patella 0.30-0.31/0.07-0.08, tibia 0.26-0.28/0.05-0.06, tarsus 0.59-0.60/0.05-0.06. Leg IV: trochanter 0.18-0.20/0.17-0.18, femoropatella 0.75-0.77/0.25-0.26, tibia 0.57-0.59/0.10-0.11, metatarsus 0.24-0.25/0.08-0.09, tarsus 0.64-0.66/0.05-0.06.

Distribution.

China (Yunnan).

Figures

Figure 5. Tyrannochthonius yamuhensis sp. nov., holotype male (A-I) A carapace B right chelicera C rallum of left chelicera D coxal spines E process of right coxa I, ventral view F palp (minus chela) G chela, retrolateral view H chela, dorsal view I male genital area. Scale bars: 0.20 mm.

Figure 8. Tyrannochthonius yamuhensis sp. nov., dorsal view, holotype male. Scale bar: 1.00 mm.