Agathidium concinnum, Mannerheim, 1852

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 : 5-8

AGATHIDIUM CONCINNUM SPECIES GROUP

DIAGNOSIS: The group is characterized by the well­developed postocular temporum which extends the lateral margin of the head posteriorly beyond the eye between 0.5 and 1.0 times the eye length (figs. 1–5). The anterior portion of the mesosternum is relatively short, much shorter than the posterior portion which is moderately to strongly concave. The humeral angles of the elytra are relatively angulate.

DISCUSSION: This species group appears to correspond to the subgenus A. (Cyphoceble) Thomson based on the long temporum. In North America the group contains five species that fall into two subgroups. The first includes A. akallebregma , A. angulare , and A. mollinum which share the presence of a male mandibular horn (e.g., figs. 17–20), moderately elongate body shape, and strongly concave posterior portion of the mesosternum. The second group includes A. hatchi and A. concinnum which are large species (very large in the case of A. hat­ chi) and are characterized by the lack of a male mandibular horn, a broad, depressed body form (e.g., fig. 2), and weakly concave posterior portion of the mesosternum. Of course, given the lack of a cladistic analysis it is impossible to say which of these states is derived. However, given the presence of a prominent left mandibular horn in at least some of these species (certainly an apomorphy within the Agathidiini ), they may be related to the members of the A. brevisternum and A. pulchrum species groups (= subgenus A. (Neoceble) auctorum ). Some species of the A. pulchrum group have a relatively long temporum, even approaching half the length of the eye. The gradational nature of this feature in Nearctic Agathidium further suggests that these species groups may not each be monophyletic.

These species occur in far western and northern North America east to the northeastern part of the continent.

KEY TO A. CONCINNUM SPECIES