Pantomorus obrieni belongs to P. viridisquamosus species group, that was described by Lanteri & Loiácono (1990). It differentiates from the latter species because is smaller, with strongly conical rostrum, flanks of pronotum slightly curved and shorter elytra. Vestiture is mostly green as in P. viridisquamosus, but slightly paler, and pinkish or copper-colored on head, legs, venter and suture of elytra.

Unknown.

Associated with native vegetation of the Chacoan and Paranaense biogeographic provinces.