Hessebius ruoergaiensis, Qiao, Penghai, Qin, Wen, Ma, Huiqin, Su, Jianping & Zhang, Tongzuo, 2018

Qiao, Penghai, Qin, Wen, Ma, Huiqin, Su, Jianping & Zhang, Tongzuo, 2018, Two new species of the genus Hessebius Verhoeff, 1941 from China (Lithobiomorpha, Lithobiidae), ZooKeys 735, pp. 65-82 : 71-73

Hessebius ruoergaiensis sp. n.

Etymology.

The name of the species is from the type locality.

Holotype.

♀, numbered REG 11, China, North of Sichuan province, Ruoergai County, 33.397°N, 103.201°E, 14. V. 2012, under stones on steppe, at 3588 m above sea level, leg. Gonghua Lin, Weiping Li. Paratypes: 6 ♂, 3 ♀, same data as holotype.

Diagnosis.

Body length 9.2-10.0 mm; antennae composed of 19-20 antennomeres; 7-10 dark ocelli on each side; Tömösváry’s organ ovate to round, larger to the adjoining ocelli; 2+2 triangular sharp prosternal teeth; porodonts long and strong, lateral to lateral tooth; posterior angles of all tergites round; legs 14 and 15 thicker than anterior ones; coxal pores 3-5, ovate to round, arranged in one row; female gonopods with 2 bullet-shaped spurs, the second article of the female gonopods extend ing backwards bearing 5 lateral spines; terminal claw of the third article simple, with inconspicuous triangular ventral accessory denticles; male gonopods short and small with 2 long setae.

Description.

Holotype (female). Body 9.2 mm length. Cephalic plate 1.0 mm length, 1.2 mm width.

Colour: body pale yellow; antennae and distal part of forcipules brown; cephalic plate, TT 1, 2 dark and median and posterior parts of TT 3-14 dark forming a line; pleural region and SS pale yellow with dark hue; legs pale yellow with dark hue excluding tarsus yellow.

Antennae: 41.6% of body-length with 20 moderately elongate articles; the basal one wider than long; the 8, 9, 10, 11 elongate; the ultimate one is three times longer than wide. Abundance setae scattered on the surfaces of from the first to the last.

Cephalic plate wider than long, with clear transverse suture; median furrow on cephalic plate absent; lateral margin discontinuous, posterior margin slightly concave; moderately long setae scattered along marginal ridge and cephalic plate (Fig. 3A).

Two posterior large ocelli and eight smaller ocelli arranged in three rows (Fig. 3B). Tömösváry’s organ ovate, larger than the adjoining ocelli, some distance from the adjoining ocelli, situated on ventral side of cephalic pleurite.

Prosternum: subtrapezoidal coxosternite with narrow, straight dental margin; 2+2 subtriangular teeth as extensions of the coxosternite teeth; median incision “U” shaped; long and strong setiform porodonts; lateral borders without shoulders; pretarsal section of forcipules slightly longer than tarsal section; 3 lines of short setae and 1 moderately long setae arrange on ventral side of coxosternite (Fig. 3D).

Tergites smooth, angulation of posterolateral corners of tergites all rounded without triangular projections; T1 narrower than head and T3, concave transverse; all tergites with lateral margins; TT 1, 3 and 5 with complete posterior margins, TT 7, 8, 10, 12, and 14 incomplete; posterior margins of TT 3, 5, 8, 10, and 12 a little concave (Fig. 3A), T14 gently concave, TT1, 7, and 9 transverse, tergite of intermediate segment weakly convex. Short to long setae sparsely dispersed along lateral borders and posterior corners, a band of setae on TT 10, 12 (Fig. 3A).

Sternites smooth, S1 subsquare, SS 2-14 trapeziform, posterolateral narrower than anterolateral. One to three pairs of setae symmetrical on anterior corners; one pair of setae on posterolateral margins; a few setae distributed along posterior margins; a band of setae on anterior margins of SS 2-7.

Legs: tarsal articulation on anterior pairs of legs fused on dorsal side of leg, distinct ventrally from 1st to 13th, on 14th and 15th leg divided into basitarsus and distitarsus; pretarsus claws moderately long, curved ventrally on all legs; anterior and posterior accessory spines present from the 1st to the 14th leg, only posterior accessory spines on the 15th leg; anterior accessory spines long and straight, nearly half of length of the main claw, posterior accessory claws strong and curved, nearly a third length of the main claw; Legs 14-15 (Fig. 3A) thickened. Numerous short to long setae fairly evenly distributed on all sections along legs. Legs’ plectrotaxy as in Table 2. In male, one comparatively obvious furrow on the dorsal side of the tibia of legs 14 and 15 (Fig. 3G).

15 th legs: approx. one third of body-length. Leg 15 basitarsus 129% length of distitarsus; basitarsus 84% length of tibia; tibia 2.6 times longer than maximal width, basitarsus 3.6 times, distitarsus 3.2 times. Basitarsus nearly the same length of distitarsus on leg 14.

Glandular pores: on the ventral side of femur tibia and tarsus of 14th and 15th legs only.

Coxal pores: on legs 12-15; set in shallow groove; the inner one smaller, circular, separated from one another by their own diameter or less; 5,5,5,5/5,5,5,4 (holotype) or 4444 in females; 4443, 3444 or 3333 in males.

Female: S15 subtrapeziform with short to long setae covered. The first genital sternite bears approx. 48 setae, posterior margin of which moderately embayed between gonopod articulations. Two long conical spurs on the female gonopod, the proximal ones smaller (Fig. 3E); Claw of female gonopod with small triangular ventral accessory denticles (Fig. 3F); five stronger and curved spines like thorn on distinct dorsodistal projection (Fig. 3F); 15 or 16 setae arranged in three rows on basal article of gonopod, six long setae on second article, 3 long setae on third (Fig. 3E).

Comparatively long setae distribute on male first genital sternite with fewer setae near S 15; posterior median margin of the first genital sternite deeply concave between gonopods; male gonopod short with two setae sometimes retracted from tergite of first genital sternite (Fig. 3H).

Variations.

body 9.2-10.0 mm long, cephalic plate 0.9-1.2 mm wide, 0.9-1.2 mm long; 1+3, 2, 1-1+4, 3, 2 ocelli (Fig. 3B, C); Leg 15: basitarsus 129-138% length of distitarsus, basitarsus 84-94% length of tibia; tibia 2.6-2.8 times longer than maximal width, basitarsus 3.6-3.9 times, distitarsus 3-3.2 times.

Remarks.

Hessebius ruoergaiensis sp. n. is very similar to Hessebius jangseanus : the number of ocelli of both species are overlapped, but H. ruoergaiensis has fewer ocelli, no more than ten; fewer coxal pores in H. ruoergaiensis , no more than five; the distribution of accessory claw on the legs is the same in both species; however, the tibia of the 14th and 15th leg of H. ruoergaiensis have dorsal sulcus which is absent in H. jangseanus ; the plectrotaxy of legs also similar but different.