Agathidium oniscoides, Palisot de Beauvois, 1817

MILLER, KELLY B. & WHEELER, QUENTIN D., 2005, Slime-Mold Beetles Of The Genus Agathidium Panzer In North And Central America, Part Ii. Coleoptera: Leiodidae, Bulletin of the American Museum of Natural History 2005 (291), pp. 1-167 : 70-72

AGATHIDIUM ONISCOIDES SPECIES GROUP

DIAGNOSIS: This group is characterized by the relatively horizontal ventral surface of the mesosternum, which is in approximately the same plane as the metasternum (with the posterior portion not concave), the broad anterior portion of the mesosternum which generally has a prominent medial carina, highly contractile body form, very broad pronotum, and broadly rounded posterolateral angles of the pronotum (fig. 105), broadly rounded humeral angles of the elytra, relatively impunctate dorsal surface and presence of distinct, oblique femoral lines on the metasternum which often meet medially in a prominent, posteriorly directed flange. The species range from minute to large, are usually dark redbrown to piceous dorsally, and males often have a distinctive tooth on the posterior margin of the metafemur.

DISCUSSION: This species group corresponds to the subgenus Agathidium sensu stricto auctorum . The group includes a fantastic diversity of relatively similar species. Although a large number of species are described here, it is certainly likely that the true species diversity remains yet to be described. The species are particularly numerous in the eastern United States, particularly the southern Appalachians, and in the mountains of Mexico, where we especially expect the number of species to increase with additional collection of specimens. Many of the species in this group are apparently cryptic in habitat and are often collected from forest litter samples and Berlese extraction. Often these species have the eyes reduced and are apterous. The strongly contractile nature and ball­ shaped habitus make these species distinctive.

To facilitate management of this large group, the species were arranged into subgroups. Unfortunately, a great many of the species and groups of species are identifiable only from males, and many of these only by dissection of genitalia. The key relies on dissection and critical examination of male genitalia, an unavoidable problem because of the state of our knowledge of the group at this time. Other characters of importance are the shape of the male metafemoral tooth, the presence of modifications such as lobes or tubercles on the surface of the gula, the development of the eyes and the nature of the oblique metasternal carinae and male metasternal fovea.

KEY TO A. ONISCOIDES SPECIES