Agathidium compressidens, Fall, 1934

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 : 63-64

AGATHIDIUM COMPRESSIDENS SPECIES GROUP

DIAGNOSIS: This group differs from others by the combination of moderately strong contractility, impunctate dorsal surfaces, broad anterior and posterior portions of the mesosternum, posterior portion of the mesosternum moderately strongly concave, and metasternum relatively narrow medially and with very weakly developed oblique carinae.

DISCUSSION: Fall (1934b) and Hatch (1936) allied the species A. compressidens with members of the A. oniscoides group while pointing out some of the differences. The species exhibit the contractility and lack of dorsal punctation similar to members of the A. oniscoides group. They also have the humeral angles of the elytron obsolete. However, the mesosternum has a relatively broad posterior portion that is distinctly concave. Also, the oblique metasternal carinae are only weakly developed. The species are also similar to certain members of the A. revolvens group, such as A. virile , which have a somewhat convex posterior portion of the mesosternum. Thus, the members of the A. compressidens group appear intermediate between these groups and others, and they do not clearly fit into any. Therefore, we have elected to place them in their own group. Two of the three species, one eastern and one western, possess a prominent medial lobe on the first visible abdominal sternite, but the third species, the western A. fenderi , does not. The abdominal lobe is a seemingly clear synapomorphy, but the similarities between A. fenderi and the lobed species are not strong, and this grouping may be artificial.

KEY TO A. COMPRESSIDENS