Rhomboidederes ravidus Click here for a larger view

Diagnosis.--Key characters: Ommatidial size coarse (Fig. 39b); prosternal process widened, not planar, expanded apically (Fig. 18); mesal antennal spines present (Figs. 8b, 9b); elytral humeri without tooth at epipleural margin; pronotum with impunctate regions; femoral carinae absent; procoxal cavities widely open laterally (Fig. 17); lateral projections into mesocoxae from mesosternum absent (Fig. 20); femoral apices rounded (Fig. 26); pronotum without distinctive circular callus at base; femora clavate and pedunculate (Fig. 37a); tibial carinae present (Fig. 22); elytra without dense patterns of golden and/or silver pubescence; antennae strongly, doubly carinate dorsally (Fig. 45c); elytra with strong apicolateral spines in most specimens; pronotal punctation alveolate with small punctures in and around larger impressions; pronotum glabrous except for scattered long flying-hairs; pronotum expanded laterally to broad points. Length: 8-9 mm.

Distribution and Diversity.--Northern South America to Uruguay. Four species.

Discussion.--Rhomboidederes fell among the clade containing primarily South American genera including the Mallocera and allies clade (Fig. 59) and Sphaerion and allies clade (Fig. 60).

The distinctly multicarinate antennae (doubly carinate dorsally), pronotum with acute, broad-based lateral tubercles, pedunculate and unarmed femora, and small size make this a distinctive genus.