Hessebius luquensis, 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 : 68-71

Hessebius luquensis sp. n.

Type data.

Holotype: female numbered LQ 8 (Fig. 2 A–F), body length 10.4 mm, from Luqu County, the Gannan Prefecture, Gansu province, China, 34.75647°N, 102.57245°E, 13 May 2012, 3192 meters above sea level, leg. Gonghua Lin, Weiping Li. Paratypes: 8 females, 2 males, same data as holotype.

Habitat.

Speciemens were collected under stones along roadside on steppes from Luqu.

Etymology.

The name is derived from the locality Luqu where the species is discovered. Luqu country is situated in the eastern edge of the Tibetan Plateau standing on the junction of Gansu, Qinghai and Sichuan Provinces.

Diagnosis.

Body length 8.5-12.3 mm; head slightly widened; antennae of 20 antennomeres; 7-10 ocelli arranged in three rows; Tömösváry’s organ oval, almost equal in size to neighboring ocelli (Fig. 2B); lateral margins of forcipular coxosternite slanting; anterior margin with 2 + 2 sharp teeth and with setiform porodonts; tergites without triangular posterolateral process, a line of setae along posterior border of TT 8 and 10; legs 14 and 15 thicker than anterior ones in both sexes; a dorsal furrow on the tibia of legs 14-15 on male; coxal pores 3-6, round, arranged in one row; female gonopods with two moderately long, bullet-shaped spurs, the second article of the female gonopods having a massive process; terminal claw of the third article simple, with a small triangular protuberance on basal ventral side; male gonopods short and small.

Description.

Holotype (female), body 10.4 mm long, cephalic plate 1.3 mm width, 1.2 mm length.

Colour (based on specimens in 95 % ethanol): antennomeres yellow; tergites pale yellow, with brown margin; cephalic plate and T 1 brown; pleural region and sternites pale yellow; distal part of forcipules dark brown, maxillipede coxosternum and S 15 yellow; legs pale yellow with gray hue, pretarsal claw dark brown.

Cephalic plate smooth, convex, slightly longer than wide; short to long setae scattered along the marginal ridge of the cephalic plate; setae on head shield symmetrically arranged, three pairs between antennocellar and transverse suture, two pairs behind these sutures; frontal marginal ridge with clear transverse suture; projection of lateral marginal conspicuously discontinuous; posterior marginal ridge slightly concave without median thickening.

Ocelli (Fig. 2B): translucent with dark pigment, 1 + 4, 3, 2 ocelli on each cephalic plateau, arranged in three rows. The posterior ocellus is the biggest, seriate ocelli smaller. Tömösváry’s organ oval, nearly the same size as the adjacent ocelli, not remote, situated ventraly on anterolateral margin of cephalic pleurite.

Antennae length 3.46 mm, extending back to anterior margin of T 5, consisting of 20 elongate antennomeres covered with dense pale setae. The basal two articles enlarged, then elongate and tapering. The first article wider than long, the second article has the equal width to length, terminal article approximately 2.5 times length to width. Setation: the first two articles has fewer setae than succeeding articles especially on anterior side, then increasing, till 6 or 7, the density become constant.

Forcipular coxosternites subtrapezoidal, coxosternite with narrow, straight or slightly recurved dental margin; 2+2 teeth on dental margin, small, blunt knobs with independent sclerotization from coxosternite; porodont setiform towards its apex, much stouter than a seta at its base; no shoulders lateral to the porodont; 3 to 4 long setae along the slope, some setae scattered on ventral side of coxosternite.

Tergites smooth, T1 narrower than head and T3, subrectangular; on TT 8 and 10 there is a line of setae along posterior borders; posterior margin of TT. 1, 3, 5, 8, 10, 12, 14 a little concave, of TT. 6, 7 straight; posterior angles of all tergites rounded without triangular projections; marginal ridge narrow, entire on TT 1, 3 and 5, interrupted posteriorly on TT 7, 8, 10, 12, and 14 (Fig. 2A); tiny setae inserted in pores scattered very sparsely over the surface, more setae on anterior and posterior angles of each tergite.

Sternites trapeziform, setae scattered very sparsely on the surface; four pairs of long bristles approximately symmetrical on the anterior corner and margin, one pair on the posterior corner; among long bristles there’s small pairs of short bristles; short to long setae along posterior border, in some individuals SS 13, 14, 15 more dense.

Legs: tarsal articulations only visible with shallow ventral suture on 1st to 11th, distinct on 12th and 13th, well-defined on legs 14 and 15; leg pairs 14 and 15 thicker and longer with sparse setae in contrast to legs 1-13; pretarsus of legs 1-13 with a slightly curved, long, principal claw and smaller and thinner anterior and posterior accessory spines, anterior accessory spines long and slender, 0.33-0.5 the length of principal claw, posterior one stouter, 0.25 the length of principal claw, forming slightly larger angles with tarsal claws; accessory apical spines on the 14th vestigial, absent on the 15th; abundant glandular pores on surfaces of femur, tibia and tarsus of legs 14 and 15; short to moderately long setae scattered over the surface of legs 1-13, latter half of tarsi generally more setose with two rows of setae along ventral side, fewer setae on legs 14-15.

14th and 15th legs: swollen, 15th leg 30% of body-length, tarsus 1 4.3 times longer than wide, tarsus 2 48% length of tarsus on leg 15. Data on the leg plectrotaxy are compiled in Table 1. In the male the 14th and 15th tibia has a dorsal sulcus extending along its whole length.

Coxal pores on legs 12-15, circular; inner pores smaller. Distance between pores 2-3 times bigger than diameter of pore; formula 4, 4, 4, 4. Coxal pores set in a shallow groove arranged in a row with short to long setae scattered over the surface of apophysis.

Female S15 generally trapeziform, straight posteromedially; sternite of genital segment well sclerotised, wider than long; sternite of genital segment with posterior margin moderately concave between condyles of gonopods, except for a small, median approximately circular bulge, distal lightly sclerotised; short to long setae scattered over the surface of genital segment and lateral margins.

Female gonopods divided into three articles, the first article moderately broad, bearing 11-17 short to moderately long setae, arranged in three rows; the first article also bearing 2+2 moderately long, bullet-shaped spurs, inner spur slightly smaller and more anterior than the outer (Fig. 2D); the second article with 6 setae arranged in one rows(Fig. 2F); dorsolateral ridge of second article with a massive expansion projecting distally over the base of the third article (Fig. 2F), six short blunt spines along the dorsolateral ridge, one on the ventral side of dorsodistal projection (Fig. 2F); three moderately long setae on third article; dorsolateral setae one on the first article, eight on the second article four of which short and blunt and four on the third (Fig. 2E); one long dorsomedial setae on each article (Fig. 2E); terminal claw simple, slender and sharp, having small triangular protuberance on ventral side (Fig. 2D).

Male S15: subsemicircular, well chitinized, long setae scattered sparsely over its surface and posterior margins. Male genitalia: first genital sternite wider than long, well chitinized; posterior margin quite deeply concave between the gonopods, no bulge medially; 24 short to medium setae scattered sparsely over its surface and at lateral margins, second genital sternite with abundance seta; gonopod of a single small article with 2 seta on its surface, apically slightly chitinized, flat (Fig. 2H).

Variations.

The length of the body (from anterior to posterior) range from 8.5 mm (LQ 9) to (LQ 12) 12.3 mm. Colour of body from pale yellow to yellow brown to ferruginous. Ocelli 1 + 4, 3, 2 or 1 + 4, 2, 1 or 1 + 3, 2, 1 on the cephalic plateau. Coxal pores 4444, 4443, 5466, 6466, 5555, 4555 in female; 4444 in male. 15th legs of LQ 9 (♂): length of each of the three distal articles of the 15th legs in comparison with their own diameter, 15th tibiae: 0.76 mm/0.31 mm = 2.45x; 15th tarsus 1: 0.69 mm/0.22 mm =3.14x; 15th tarsus 2: 0.62-0.13 mm/0.06 mm = 4.77x.

Remarks.

The female of H. luquensis sp. n. is mostly similar to Hessebius longispinipes Ma, Pei and Zhu, 2009, but can be readily distinguished by the following characters: more antennomeres (20 + 20, vs. 18 + 18 in Hessebius longispinipes ), more ocelli in three rows, a bulge exists near the base of the porodont; 14th accessory spines present, apical claw of female gonopods with triangular protuberance only on the ventral side and the apex of the male gonopod flat versus hemisphere in H. longispinipes .