This species is closely related to Triaspis (T.) halidayi Martin, from South Dakota, and Triaspis (T.) kurtogaster Martin, from eastern North America. In all three species the abdominal carapace is relatively strongly longitudinally rugoso-punctate and apically emarginate, and the clypeus is transverse. The new species may be readily distinguished from kurtogaster by its non-reflexed margin of the clypeus and by its less strongly developed marginal lamella of the third abdominal tergite, and may be separated from halidayi by its stronger, coarser, general rugoseness and darker colour.