Hypomedon nasutus, Assing, 2016

Assing, Volker, 2016, On some Acanthoglossa and Hypomedon species II. Two new species, a new synonymy, and additional records (Coleoptera: Staphylinidae: Paederinae), Linzer biologische Beiträge 48 (1), pp. 317-325 : 322-324

Hypomedon nasutus nov.sp.

( Figs 14-17 )

Type material: Holotype ♂: " Thailand, Satun Prov., Thale Ban N.P. , 20 km E Satun, 400 m, 1.-4.I.1996, leg. Schulz & Vock / Holotypus ♂ Hypomedon nasutus sp.n. det. V. Assing 2016" ( cAss).

Etymology: The specific epithet is an adjective derived from the Latin noun nasus (nose) and alludes to the nose-shaped ventral process of the aedeagus.

Description: Body length 2.9 mm; length of forebody 1.5 mm. Coloration: head and pronotum dark reddish-brown; elytra reddish; abdomen reddish-brown, with the posterior portion of segment VII and segments VIII-X reddish-yellow; legs reddishyellow; antennae reddish.

Head ( Fig. 14 ) 1.23 times as broad as long; punctation coarse, moderately dense, and umbilicate; interstices with pronounced microsculpture. Eyes approximately 0.7 times as long as postocular region in dorsal view. Antenna: antennomere III approximately as broad as long; antennomeres IV-X of gradually increasing width and increasingly transverse; X approximately twice as broad as long.

Pronotum ( Fig. 14 ) 1.07 times as broad as long and 0.94 times as broad as head; punctation similar to that of head, but somewhat denser; interstices with pronounced microsculpture.

Elytra ( Fig. 14 ) approximately as long as pronotum; punctation very dense and moderately fine; interstices without microsculpture. Hind wings apparently fully developed.

Abdomen narrower than elytra; punctation dense and fine on anterior, sparse and even finer on posterior tergites; interstices with shallow microsculpture; posterior margin of tergite VII with palisade fringe.

♂: sternite VII unmodified; sternite VIII ( Fig. 15 ) weakly transverse, posterior margin convex, in the middle very indistinctly concave; aedeagus ( Figs 16-17 ) 0.32 mm long, with relatively short ventral process of characteristic shape.

Comparative notes: Hypomedon nasutus is distinguished from the externally similar H. galilaeus and H. debilicornis by the completely different shape of the ventral process of the aedeagus, the different shape of the male sternite VIII, a more transverse antennomere X, and larger punctures on the pronotum. The aedeagus of the new species is most similar to that of H. niloticus (KOCH, 1934) , but the ventral process and the sclerotized dorso-apical structure are of different shapes. Moreover, H. nasutus differs from H. niloticus by coarser and denser punctation of the head and pronotum, larger eyes, and by a less transverse and posteriorly only indistinctly concave male sternite VIII. For illustrations of H. niloticus see ASSING (2009).

Distribution: The type locality is situated in Thale Ban National Park, South Thailand (close to the border with Malaysia), at an altitude of 400 m.

Figures

Figs 14-21: Hypomedon nasutus nov.sp. (14-17) and H. bicornutus nov.sp. (18-21): (1-2) forebody; (3-10) aedeagus in lateral and in ventral view; (11-13) male sternite VIII. Scale bars: 14, 18: 0.5 mm; 15-17, 19-21: 0.2 mm.