Echiaster bivirgatus, Assing & I, 2014

Assing, V. & I, North, 2014, Three new species and additional records of Echiaster from Asia (Coleoptera: Staphylinidae: Paederinae), Linzer biologische Beiträge 46 (2), pp. 1087-1096 : 1089-1092

Echiaster bivirgatus nov.sp.

( Figs 1-8 , Map 1 )

Type material: Holotype: "NW THAILAND, W Pai, above waterfall, 800 m, 19.IV.2004, leg. W. Schawaller / Holotypus Echiaster bivirgatus sp.n. det. V. Assing 2013 " ( SMNS) . Paratypes: 1: " THAILAND, C. Rai: Mae Yao , 13:III:1982, G. de Rougemont " (cRou) ; 1: " THAILAND Doi Inthanon , 15:III:1982, G. de Rougemont " (cAss) ; 2: " Thailand, Ban Maeo Microwave , Mae Hong Son Dist., 1250 m, 15.12.1990, P. Schwendinger" ( MHNG, cAss) ; 1 [dissected prior to present study, aedeagus slightly damaged, sternite VIII completely destroyed], 2: " INDIA W. Bengal, Darjeeling distr., Mahanadi 1200 m 6.X.78, Besuchet-Löbl / Echiaster n. sp., G. de Rougemont 1999" ( MHNG, cAss) .

Etymology: The specific epithet is an adjective composed of the Latin prefix bi- (two) and the Latin adjective virgatus (striped). It alludes to the pair of reddish bands on the elytra.

Description: Body length 5.4-6.0 mm; length of forebody 2.8-3.1 mm. Species of slender habitus ( Fig. 1 ). Coloration: forebody dark-brown to blackish-brown, elytra each with a long, often slightly curved reddish band of variable width extending from the humeral angles to the posterior margin, or nearly so; abdomen blackish; legs yellowish; antennae yellowish-red to reddish with brown antennomere I.

Head ( Figs 2-3 ) approximately as broad as long, widest across eyes, behind eyes convexly narrowed towards neck in dorsal view; posterior angles obsolete; punctation coarse, areolate, and extremely dense; interstices reduced to narrow ridges; dorsal surface matt. Eyes conspicuously large, nearly as long as distance from posterior margin of eye to posterior constriction of head in dorsal view. Antenna short, 1.0- 1.1 mm long.

Pronotum ( Figs 2-3 ) slender, approximately 1.4 times as long as broad and 0.71-0.75 times as broad as head; median portion shallowly impressed in posterior two thirds, this impression with median elevation in posterior third of pronotum; punctation similar to that of head, but slightly coarser.

Elytra ( Figs 2-3 ) dimorphic, approximately 0.85 times as long and 1.4 times as broad as pronotum in macropterous morph, approximately 0.65 times as long and 1.3 times as broad as pronotum in brachypterous morph; humeral angles pronounced in macropterous morph, less pronounced in brachypterous morph; punctation very dense and granulose.

Abdomen little more than 0.9 times as broad as elytra (macropterous morph) or broader than elytra (brachypterous morph), broadest at base, gradually tapering posteriad ( Fig. 1 ); tergites III-V with very coarse and dense punctation; tergites VI-VIII with dense and fine punctation; posterior margin of tergite VII strongly convex, with palisade fringe both in macropterous and in brachypterous morph; tergite VIII distinctly oblong and with strongly convex posterior margin.

: sternite VII ( Fig. 8 ) slender, as long as broad and with very dense dark pubescence, posterior margin weakly concave; sternite VIII ( Fig. 9 ) distinctly oblong, nearly 1.3 times as long as broad, posterior margin convex and in the middle weakly concave; aedeagus 0.67 mm long and shaped as in Figs 4-7.

Intraspecific variation: The specimens from North India are all brachypterous and have elytra with a broad, nearly straight longitudinal reddish band on both elytra, whereas those from Thailand are all macropterous and have elytra with a very narrow and somewhat curved longitudinal reddish band ( Figs 2-3 ). The aedeagus ( Figs 4-7 ), however, is very similar, so that the observed differences are attributed to intra- rather than interspecific variation. Unfortunately, the abdominal sternite VIII of the sole male from India had been completely destroyed and was thus not available for examination.

Comparative notes: The new species is easily distinguished from E. unicolor and E. maior by numerous characters, particularly the larger eyes, the longer and differently coloured elytra, the more distinctly conical abdomen, the presence of a palisade fringe at the posterior margin of the male tergite VII, the more slender male sternite VII, the much shallower posterior excision of the male sternite VIII, and by the completely different morphology of the aedeagus. For illustrations of E. unicolor and E. maior see ASSING (2013).

Distribution and natural history: The specimens were collected in four localities in Thailand and one in North India ( Map 1 ), the holotype at an altitude of 800 m, two of the paratypes from Thailand at 1250 m, and the specimens from India at 1200 m. Additional data are not available.

Figures

Map 1: Distribution of Echiaster species in Asia. Echiaster discrepans (white circles); E. bivirgatus (white diamonds); E. maior (white triangles); E. paulexcisus (black diamond); E. unicolor (black circles).

Figs 1-7: Echiaster bivirgatus nov.sp. (1-2, 4-5: holotype; 3, 6-7: paratype from North India): (1) habitus; (2-3) forebody; (4-7) aedeagus in lateral and in ventral view. Scale bars: 1-3: 1.0 mm; 4-7: 0.2 mm.

Figs 8-13: Echiaster bivirgatus nov.sp., holotype (8-9) and E. paulexcisus nov.sp. (10-13): (8) male sternite VII; (9, 11) male sternite VIII; (10) forebody; (12) aedeagus in lateral view; (13) apical portion of aedeagus in ventral view. Scale bars: 10: 1.0 mm; 8-9, 11-13: 0.2 mm.