Species examined.--P. intricatum Galileo & Martins, 1992 (holotype)

Diagnosis.--Key characters: Ommatidial size coarse (Fig. 39b); prosternal process not planar, expanded at apex (Fig. 18); mesal antennal spines absent (third antennomere minutely dentiform); lateral projections from mesosternum into mesocoxae present (Fig. 21); procoxal cavities open laterally (Fig. 17); pronotum at middle slightly wider than elytra (Fig. 41e); third antennomere approximately half length of pronotum (Fig. 46a); terminal maxillary palpomeres greatly expanded apically and very short (as in Fig. 5b); femoral apices rounded (Fig. 26); femora clavate (Fig. 37b); elytral apices without spines. Length: 8 mm.

Distribution and Diversity.--Brazil (Mato Grosso do Sul), Paraguay. Monotypic.

Discussion.--Because no specimens of this rare taxon were available for inclusion in the phylogenetic analysis, its relationships are 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 unspined antennae, very broad pronotum, greatly expanded terminal maxillary palpomeres, unspined femoral and elytral apices, and strongly clavate femora readily identify Piezophidion.