Agathidium revolvens

WHEELER, QUENTIN D. & MILLER, KELLY B., 2005, Slime-Mold Beetles Of The Genus Agathidium Panzer In North And Central America, Part I. Coleoptera: Leiodidae, Bulletin of the American Museum of Natural History 2005 (290), pp. 1-95 : 58

AGATHIDIUM REVOLVENS SPECIES GROUP

DIAGNOSIS: Body convex, somewhat elongate, elytra sometimes distinctly dorsoventrally compressed; pronotum more or less convex; body partially contractile; color nearly uniform, pale to dark reddish­brown, rarely nearly black; head with postocular temporum more or less prominent, always much shorter than eye; tarsal formula male: female 5–5–4:5–4–4; mesosternum nearly horizontal between mesocoxae, divided into anterior and posterior parts, anterior part with distinct median carina; metasternum without paired oblique lines or, if present, no more than very short, indistinct traces; elytra usually distinctly punctate, punctures sometimes in more­or­less evident serial rows.

DISCUSSION: Our A. revolvens species group appears to be related to certain Palearctic members of the subgenus A. ( Neoceble ) centered around A. nigripenne Fabricius. The group, as interpreted here, includes seven species recognized by Fall (1934) plus several species described as new. Fall (1934) separated these species into two informal groups. One group included species that, like A. revolvens , are relatively broadly oval. The other group included putatively related species that are comparatively dorsoventrally compressed and elongate, a form most fully expressed in A. depressum . The distinction between the comparatively broader, more convex forms and the elongate, more depressed forms is not consistent, however, and this supposed contrast is useful only in comparative descriptions of pairs of species.

In general, the species in this group possess easily discerned differences in shape of the aedeagus, and dissection of males presents the best avenue for species identification. However, there are a number of external differences, including subtle variation in the type and degree of punctation on head, pronotum and elytron, body shape, and the male metasternal foveae. These characters are less consistent and require critical examination of specimens. The following key relies heavily on external characters. However, most certain species identification is best done by dissection of male specimens and comparison of aedeagi with the illustrations.

KEY TO A. REVOLVENS SPECIES