Naupactus purpureoviolaceus is similar to N. tremolerasi in size and general body shape. It mainly differentiates from the latter because the scaly vestiture is usually purple-violet and sparse; the antennae are more slender, the pronotum less rugose, the humeri indistinct, the elytral intervals less flat, and the scales usually do not concentrate near the punctures of striae. The scutellum is white; the elytra setae are short and recumbent; and the corbels of the hind tibiae are absent, same as in N. tremolerasi.

The synonym Asynonychus persimilis corresponds to a whitish variety of N. purpureoviolaceus, with dark stripes along the uneven intervals (sparse scaly vestiture that leaves the integument exposed) and light stripes along the even intervals of the elytra (dense scaly vestiture).

Males are scarce in populations of this species, which it is infected with the bacterium Wolbachia, that induces parthenogenesis in several species of Naupactini (Rodriguero et al. 2010a).

Phaseolus sp and Glycine max L. (Merr.) (Fabaceae) in southern Brazil and northeastern Argentina (Link & Busanello 1982, Lanteri et al. 2013a), and cotton, Gossypium hirsutum L. (Malvaceae), in Paraguay.

It is mainly associated with native vegetation of the Chacoan and Paranaense biogeographic provinces, inhabiting in areas close to rivers and streams.