Atheta (Microdota) dimorpha ASSING 2006

Assing, V., 2009, New species and additional records of Homalotini, Athetini, Pygostenini, and Lomechusini from Yunnan, China (Coleoptera: Staphylinidae: Aleocharinae), Linzer biologische Beiträge 41 (1), pp. 485-507 : 491-492

Atheta (Microdota) dimorpha ASSING 2006

R e m a r k s: While comparing the new species described in the following sections with the descriptions of Microdota species in ASSING (2006a), I became aware of the fact that a significant part of the description of A. dimorpha in the original manuscript had mysteriously disappeared during the publishing process; this omission evidently escaped my attention when correcting the proofs. Therefore, a full redescription is here provided; the figure references refer to illustrations in ASSING (2006a).

R e d e s c r i p t i o n: 2.1-2.6 mm. Habitus as in figure 27. Coloration: head and pronotum brown to blackish-brown, with the head usually slightly darker than pronotum; elytra brown; abdomen blackish-brown, with the apex (posterior margin of segment VII, segments VIII-X) distinctly paler, yellowish; legs yellowish-brown; antennae darkbrown, with the basal 3-4 antennomeres yellowish to yellowish-brown.

Head with sexual dimorphism, of suborbicular shape (figures 28-29); eyes very small, composed only of approximately 10 ommatidia (figure 30), not protruding from lateral outline of head, less than 1/4 the length of postocular region in dorsal view; integument with distinct microreticulation; punctation sparse, fine, and very shallow, barely noticeable. Antenna distinctly incrassate apically (figure 31); antennomere III distinctly shorter than II; IV moderately transverse; V-X of increasing width and increasingly transverse; X approximately twice as wide as long.

Pronotum, with conspicuous sexual dimorphism, small, approximately 1.1 times as wide as long and 1.05-1.10 times as wide as head (figures 28-29); maximal width in anterior half; pubescence of midline directed cephalad; microsculpture distinct.

Elytra slightly wider than and at suture approximately 0.6 times as long as pronotum (figures 28-29); microreticulation less distinct than that of head and pronotum; punctation very fine and relatively sparse. Hind wings reduced.

Abdomen approximately 1.2 times as wide as elytra, maximal width at segment V (figure 27); punctation fine and relatively sparse; microreticulation distinct; posterior margin of tergite VII without palisade fringe.

Ƌ: head more or less depressed dorsally; pronotum with very pronounced microsculpture, matt, and with conspicuously granulose punctation (figure 28); tergite VII broadly concave posteriorly; posterior margin of tergite VIII weakly concave in the middle (figure 45); sternite VIII much longer than tergite VIII, its posterior margin strongly convex (figure 46); median lobe of aedeagus of very distinctive shape (figures 32-34); apical lobe of paramere shaped as in figure 35, with three relatively short setae.

♀: head not depressed; pronotum with weaker microsculpture and with very fine punctation (figure 29); posterior margin of tergite VII more weakly concave; tergite VIII with almost truncate posterior margin (figure 47); sternite VIII slightly longer than tergite VIII, its posterior margin in the middle weakly concave and with long modified marginal setae (figure 48); spermatheca as in figure 36.