Micrillus indicus (EPPELSHEIM 1890)

Assing, V., 2013, On the Palaearctic and Oriental species of Scymbalium and Micrillus (Coleoptera: Staphylinidae: Paederinae), Linzer biologische Beiträge 45 (2), pp. 1479-1520 : 1495-1496

Micrillus indicus (EPPELSHEIM 1890)

( Map 3 )

Scymbalium indicum EPPELSHEIM 1890: 277 f.

Type material examined Lectotype, present designation: " indicum Epp. , Nagpore, India centr., D. Bomford. / c. Epplsh. Steind. d. / Typus / Lectotypus Scymbalium indicum Eppelsheim , desig. V. Assing 2012 / Micrillus indicus (Eppelsheim) , det. V. Assing 2012" (NHMW) . Paralectotypes: 1, 1: same data as lectotype (NHMW) .

Additional material examined: India:1, Uttaranchal, Haldwani Division, Kumaon, at light, VI.1923, leg. Champion (BMNH).

Comment: The original description of S. indicum is based on several syntypes ("pluries captum") from " India centrali, a D. Dr. Bomford prope Nagpore [= Nagpur]" (EPPELSHEIM 1890). Three type specimens, two males and one female, were located in the collections of the NHMW. The male in better condition is designated as the lectotype. Three specimens of uncertain type status from the type locality in the collections of the MNHUB were studied earlier ( ASSING 2008).

Redescription: Body length 4.7-5.5 mm; length of forebody 2.5-3.0 mm. Coloration: whole body including appendages pale reddish, with the abdomen sometimes slightly darker and the elytra often somewhat paler.

Head weakly oblong at most, 1.00-1.07 times as long as broad; punctation sparse, composed of some larger punctures and interspersed micropunctures on frons, as well as in posterior and lateral portions; median dorsal surface impunctate; integument with fine and shallow microsculpture. Eyes small, but of somewhat variable size, and weakly convex, one-third to one-half as long as postocular region in dorsal view. Antennae slender, 2.0- 2.4 mm long; antennomeres III-VI approximately three times as long as broad or nearly so; VII approximately twice as long as broad; VIII-X at least 1.5 times as long as broad. Apical joint of maxillary palpus of conical shape and less than half the length of preapical joint.

Pronotum approximately 1.15 times as long as broad and 1.05 times as broad as head, widest a short distance behind anterior angles; posterior margin distinctly concave; dorsal surface with rather dense micropunctation, on either side of midline with a series of five not very evident macropunctures; interstices with or without very shallow traces of microsculpture.

Elytra approximately 0.9 times as long as pronotum; punctation fine, very dense, and somewhat asperate. Hind wings fully developed. Metatarsomere long, slightly longer than the combined length of II and III.

Abdomen approximately as broad as, or slightly narrower than elytra; punctation moderately fine and moderately dense; microsculpture mostly distinct, occasionally almost obsolete on tergite VII; posterior margin of tergite VII with palisade fringe.

: sternite VIII distinctly oblong, posterior excision narrow and rather deep; aedeagus small, nearly 0.4 mm long, strongly asymmetric, and of distinctive shape.

Comparative notes: As regards the habitus and coloration, M. indicus somewhat resembles small specimens of the pale-coloured morph of M. testaceus , but the head is smaller, the antennae are more slender, the elytra are longer, the pronotal punctation is denser, and the hind margin of the pronotum is more distinctly concave. Based on the morphology of the maxillary palpus, the structure of the abdominal segments IX-X, the shape of the male sternite VII (narrow and deep posterior excision), as well as on the morphology of the aedeagus (asymmetric; presence of distinctly sclerotised internal structures), M. indicus undoubtedly belongs to the M. aegyptiacus group. It is readily distinguished from M. distortus (see below) by larger body size, the much longer and more slender antennae, the much longer and more slender tibiae and tarsi, the more slender pronotum, the broader and deeper posterior excision of the male sternite VIII, as well as by the completely different morphology of the aedeagus. The external and male sexual characters of M. indicus are illustrated in ASSING (2008). For characters distinguishing M. indicus from M. nigriceps , its closest relative, see the comparative notes in the following section.

Distribution and natural history: The known distribution is confined to two localities in North and Central India ( Map 3 ). The additional specimen was collected at a light source.

Figures

Map 3: Distributions of Micrillus indicus (EPPELSHEIM) (triangles), M. nigriceps (CAMERON) (diamonds), M. intermedius (CAMERON) (open and filled circles), and M. siamensis nov.sp. (filled circle) in the Oriental region, based on examined records.