Stenus mendaensis, Shuai & Tang & Luo, 2020

Shuai, Qi, Tang, Liang & Luo, Yong-Ting, 2020, A review of the Stenus aureolus group of China (Coleoptera: Staphylinidae), Acta Entomologica Musei Nationalis Pragae (Acta. Ent. Mus. Natl. Pragae) 60 (2), pp. 615-627 : 620-623

Stenus mendaensis sp. nov.

( Figs 5 , 23–26 )

Type material. Hඈඅඈඍඒඉൾ: CHINA: QංඇǤΗൺං: J, glued on a card with labels as follows: “Menda N. R., alt. 2200–2500 m, 24.vii.2004, Hu, Tang & Zhu leg.”, “ Holotype / Stenus mendaensis / Shuai, Tang & Luo” [red handwritten label] ( SHNU). Pൺඋൺඍඒඉൾඌ: CHINA: QංඇǤΗൺං: 2 ♀♀, same label data as for the holotype ( SHNU).

Differential diagnosis. The new species can be distinguished from other species of the Stenus aureolus group by the combination of the following characters: smaller in body size, head and pronotum with interstices partially and indistinctly reticulated, elytra short (brachypterous), hind tarsomeres IV relatively simple; aedeagus with apical sclerotized area of median lobe medium in length ( Fig. 24 ); spermatheca with spermatheca duct complicated coiled at the first bend ( Fig. 26 ).

Description. Brachypterous. Body entirely black, antennae reddish brown with club darker, maxillary palpi with first and basal half of second segments yellowish brown, remaining parts reddish brown, legs reddish brown with knees darker.

Measurements. BL: 3.5–3.7 mm, FL: 1.6–1.7 mm. HW: 0.72–0.76 mm, PL: 0.52–0.56 mm, PW: 0.56–0.59 mm, EL: 0.59–0.64 mm, EW: 0.73–0.78 mm, SL: 0.43–0.46 mm.

Head 0.98–1.00 times as wide as elytra; interocular area with two deep longitudinal furrows, median portion convex, extending a little beneath level of inner eye margins; punctures mostly round and more or less confluent, varied in size, diameter of large punctures slightly narrower than apical cross section of antennal segment II; interstices partially and indistinctly microsculptured, distinctly narrower than half the diameter of punctures. Paraglossa oval.

Pronotum 0.93–0.97 times as long as wide; disk uneven, with median longitudinal furrow broad and deep, which is about 4/5 as long as pronotum, a transverse impression near anterior margin and two impressions near posterior margin; punctures confluent and somewhat irregular, similar size to those of head; interstices indistinctly microsculptured and rugae-like, narrower than half the diameter of punctures except for those in actual middle of longitudinal furrow, which could be slightly wider than diameter of punctures and distinctly reticulated.

Elytra 0.80–0.85 times as long as wide; disk relatively even, with indistinct humeral impression, indistinct postero-lateral impression and shallow sutural impression; punctures and interstices similar to those of pronotum but a little larger in size. Hind wings very short and nonfunctional, a little shorter than half the elytra.

Legs. Hind legs with tarsomeres IV shallowly emarginated on apical margin.

Abdomen subcylindrical; segments III–VI with broad paratergites, those of tergite 4 as broad as metatibiae at apex, tergite VII without apical membranous fringe; punctures elliptic, becoming slightly smaller posteriad; interstices indistinctly reticulated in tergite III, gradually becoming distinct in following tergites, interstices narrower than half the diameter of punctures on basal four tergites.

Male. Mesotibiae and metatibiae each with tooth on inner side of apex; sternite VIII with triangular emargination in middle of posterior margin; sternite IX ( Fig. 25 ) with long apicolateral projections, posterior margin serrate. Aedeagus ( Figs 23, 24 ) slender; apical sclerotized area of median lobe subtriangular with pointed tip; expulsion clasps large, strongly sclerotized; copulatory tube long and broad; parameres much longer than median lobe, swollen in apical parts, each with two groups of setae on apico-internal margins: 11–12 setae in distal and 5–6 setae in basal group.

Female. Sternite VIII prominent in middle of posterior margin; spermatheca ( Fig. 26 ) with basal porch scleroti- zed, spermathecal duct strongly sclerotized and coiled, capsule small.

Etymology. The specific name is derived from the type locality of this species; adjective.

Distribution. China (Qinghai), only known from the type locality.

Figures

Figs 1–5. Habitus. 1 – Stenus aureolus Fauvel, 1875; 2 – S. trigonuroides Zheng, 1993; 3 – S. musicola Cameron, 1930; 4 – S. nigraureolus Ryvkin, 2003; 5 – S. mendaensis sp. nov. Scale bars = 1 mm.

Figs 19–26. Sexual characters. 19–21 – Stenus musicola Cameron, 1930; 22 – S. nigraureolus Ryvkin, 2003; 23–26 – S. mendaensis sp. nov. 19, 20, 23, 24 – aedeagus; 21, 25 – male sternite IX; 22, 26 – spermatheca. Scale bars = 0.25 mm.