Diagnosis.--Key characters: Ommatidial size coarse (Fig. 39b); prosternal process not planar, apex expanded (Fig. 18); mesal antennal spines present (Figs. 8b, 9b); antennomeres 3-5 strongly bicarinate dorsally, 7-10 unicarinate dorsally; pronotal impunctate regions present; pronotum without longitudinal rugosities or large, regularly-sized punctures; pronotum with broad-based acute lateral tubercles; femoral carinae absent; procoxal cavities widely open laterally (Fig. 17); lateral projections into mesocoxae from mesosternum absent (Fig. 20); femoral apices rounded (Fig. 26); tibial carinae present (Fig. 22); femora clavate (Fig. 37b); apicosutural spines of elytra weak; apicolateral spines of elytra pronounced and in normal lateral position; basal sixth of elytra covered with short sericeous pubescence (Martins & Napp, 1992); pronotum with three large, mirror-like glabrous calli (two anterolateral, one median), otherwise covered with very short recumbent pubescence and finely punctate. Length: 9 mm.

Distribution and Diversity.--Brazil (Pará). Monotypic.

Discussion.--No specimens of this monotypic taxon were available for inclusion in the phylogenetic analysis and its relationships remain unclear. It may belong within the polytomy of South American genera including the Sphaerion and allies clade (Fig. 60) and the Mallocera and allies clade (Fig. 59).

The distinctive pronotal calli and lateral pronotal tubercles, strongly clavate and unspined femora, bicarinate basal antennomeres, and sericeous pubescence of the basal sixth of the elytra, separate Pilisphaerion from other genera.