Protosphaerion signatipenne Click here for a larger view

Diagnosis.--Key characters: Ommatidial size coarse (Fig. 39b); prosternal process between procoxae slightly expanded at apex (Figs. 18, 27); mesal antennal spines present (Figs. 8b, 9b); pronotum with impunctate regions but without rugosities or large confluent punctures; procoxal cavities closed laterally (Fig. 24); femoral apices rounded (Fig. 26); procoxal cavities open posteriorly (Fig. 18); tibial carinae absent; spine of antennomere three acute (Fig. 45a, b); femora clavate or clavate-pedunculate (Fig. 37a, b); pronotum without obvious constrictions; without patches of dense yellow or white pubescence on elytra; antennae carinate (not sulcate) dorsally (Fig. 45b); elytra weakly to strongly spined apicolaterally, slightly so suturally. Length: 9-16 mm.

Distribution and Diversity.--Brazil, Guyanas. Three species.

Discussion.--Protosphaerion was one of the traditional elaphidionine taxa that fell within the outgroup after the implied weighting phylogenetic analysis (Figs. 50, 62). As discussed earlier, further character analysis and further taxon representation is needed for Protosphaerion before its relationships can be firmly demonstrated. I choose to retain its position in Elaphidionini.

The key characters place Protosphaerion near Ambonus, and the taxa differ by the presence of dense patches of yellow or white pubescence in Ambonus (Protosphaerion nearly glabrous except for numerous, long flying hairs) and antennomere three strongly sulcate in Ambonus (carinate in Protosphaerion).