Lithobius (Ezembius) datongensis, Qiao, Penghai, Qin, Wen, Ma, Huiqin, Zhang, Tongzuo, Su, Jianping & Lin, Gonghua, 2018

Qiao, Penghai, Qin, Wen, Ma, Huiqin, Zhang, Tongzuo, Su, Jianping & Lin, Gonghua, 2018, Two new species of Lithobius on Qinghai-Tibetan plateau identified from morphology and COI sequences (Lithobiomorpha: Lithobiidae), ZooKeys 785, pp. 11-28 : 12-13

Lithobius (Ezembius) datongensis sp. n.

Type material.

Holotype: female labelled DT5 (Figure 2), body length 14.2 mm, from Datong County, Qinghai province, China, 37.12494° N 101.811611° E, 21 October 2010, 2950 meters above sea level, collected by Gonghua Lin. Paratypes: one female, one male, same data as holotype.

Habitat.

Specimens were collected under stones of slope-lands covered with grass mainly of Pedicularis chinensis and shrub mainly of Potentilla fruticosa along the riverside in coniferous forest composed mainly of Picea crassifolia .

Etymology.

The name is derived from the locality Datong County where the new species was discovered.

Diagnosis.

Body length 12.3-14.2 mm; antennae composed of 20+20 articles; 10 ocelli on each side arranged in 3 irregular rows, terminal one ocellus comparatively large; To larger than the adjoining ocelli; 2+2 coxosternite teeth and setiform porodonts posterolateral to the lateralmost tooth; posterior angles of all tergites without triangular projections; tarsal articulation well-defined on all legs; legs XII–XV with DaC, leg XV with posterior accessory claw; coxal pores 4-7, round, arranged in one row; female gonopods with 2+2 moderately large, coniform spurs; claw of the third article simple, with a small triangular protuberance on basal ventral side; male gonopods short and small.

Description.

Holotype (♀), body 14.2 mm long, cephalic plate width 1.54 mm, length 1.54 mm.

Colour red-brown, with a distinct, darker, axial stripe on cephalic plate and tergites. Legs pale yellow-brown. Sternite yellow-brown with distal part brown with reddish hue.

Antennae tapering, ca. 4.3 mm long, reaching the anterior part of T V, composed of 20 elongate articles (Figure 1A). Basal article to the seventh article wider than long, following articles elongate, distal article markedly longer than wide, up to 2.2 times as long as wide. Abundant setae on the antennal surface.

Ocelli area: ten on each side, dark, arranged in three broken rows; posterior ocellus slightly larger than posterosuperior ocellus and other seriated ocelli. To slightly larger than nearest ocellus, rounded.

Cephalic plate: breath/length ratio 1.0 (1.54 mm); smooth, longer setae scattered along the entire surface sparsely and the marginal ridge of the cephalic plate. Transverse suture distinct, lateral marginal ridge discontinuous, posterior margin continuous, slightly concave (Figure 2 A).

Coxosternite: dental margin slightly concave, with 2+2 slightly acute teeth and setiform porodonts separated from the lateral tooth laterally, median diastema U-shaped; shoulders of coxosternite strongly sloping, as in Figure 2C. Scattered short setae on the anterior ventral side of coxosternite, longer and stronger setae near the porodonts.

Tergites almost smooth. The anterior part of T I is approx. the same width as cephalic plate and T III; T I and T III approximately the same width. Posterior angles of all tergites rounded without triangular projections. Posterior margin of TI straight; posterior margin of TT III, V, VIII, X, XII, and XIV concave; posterior margin of TVII convex; posterior margin of intermediate T straight; TT VI–XIV bordered laterally only (Figure 2A). Short to long setae along the lateral margin and anterior and posterior angles of each tergite.

Sternites: posterior side of sternites narrower than anterior, generally trapezoidal, smooth; SS XIII–XV with miniscule setae scattered sparsely over the surface; genital sternite more densely setose, as in Figure 2E; four to five pairs of short to long fine setae along anterior lateral borders and posterior borders of sternites; several fine setae along posterior margins of SS I– XII.

Legs: tarsal articulation of all legs distinct. Legs XIV and XV incrassate, without visible modification. Length of legs XV: F = 0.85 mm, Ti = 1.00 mm, Ts I = 0.77 mm, Ts II = 0.54 mm. Legs XII– XV with DaC. All legs with fairly long curved claws; legs I– XIV with anterior and posterior accessory spurs, anterior accessory spur moderately long and slender, posterior accessory spur slightly more robust; the anterior accessory spines form relatively small angles with the main claw, the posterior accessory spines form relatively large angles with the main claw; posterior accessory spines on legs XIV. Numerous glandular pores scattered on the surface of prefemur, femur, tibia, tarsus of legs XIV and XIV; short to long comparatively long setae scattered very sparsely over the surface of all segments of legs I– XIII, more setae scattered on the whole surface of tarsus, slightly thick setae arranged in two rows on the ventral side of tarsus. Plectrotaxy as presented in Table 2.

Coxal pores present on legs XII–XV, rounded and separated by distance 0.2-2.5 times greater than their own diameter; inner pores smaller than neighbouring ones; formula 4655 and 5575. Coxal pores 4654 and 4554 in male. Coxal pore field set in a relatively shallow groove, the coxal pore-field fringe with prominence. Prominence with short to moderately long setae sparsely scattered over the surface.

Female posterior segment S XV generally trapeziform, straight posteromedially; sternite of genital segment wider than long with posterior margin moderately concave between condyles of gonopods, except for a small, median bulge; distal part lightly sclerotised; short to long setae scattered over the surface of genital segment and lateral margins. Basal article of gonopod bearing 22-25 setae, with two blunt spurs of approximately equal size at distal end of slender, elongate process and three long spines on dorsolateral side; second article of gonopod with 5-6 setae and five long curved spines on dorsolateral side; third article with two setae (Figure 2E). Claw undivided, bearing a small triangular protuberance on ventral side (Figure 2D).

Male posterior segment (Figure 2F) S XV subtrapeziform, long setae scattered sparsely over its surface. Sternite of genital segment obviously smaller than the female, well sclerotized; posterior margin quite deeply concave between the gonopods, no bulge medially; gonopods short, appearing as a hemispherical bulge, one segmented, with three setae. Male leg XV not modified.

Variations.

Body length 12.3-14.2 mm; 9-10 ocelli; coxal pores 4655, 5575, or 5544 in female, 4654 and 4554 in male.

Remarks.

The new species can be easily distinguished from the other species of the subgenus of Ezembius of China except Ezembius anabilineatus by the apical claw of female gonopods simple with a small subtriangular protuberance on the ventral side. It differs from E. anabilineatus in many aspects, such as a larger body, fewer antennal articles (20+20, vs. 23+23 in E. anabilineatus ), more ocelli, a DaC spine on legs XII–XV (only on legs XIV and XV in E. anabilineatus ), and a posterior accessory spur present on legs XV present. It differs from Lithobius (Ezembius) longibasitarsus sp. n. by having posterior accessory spur on XV legs, fewer ocelli (10 versus up to 14 in E. longibarsitarsus ) and different plectrotaxy (VmTr absent on legs XII and XIII vs. present).