Morphologically, the animals resemble the representatives of the genus Tisamenus, but differ among other things by the small, scaly, rudimentary elytra in both sexes.

In common with Tisamenus, Pterobrimus has large, laterally flattened spines on the front edge of the pronotum and indicated triangle on the top of the mesonotum.

This ovipositor is formed dorsally from the supraanal plate (also called epiproct) and is serrated at the tip, atypical for Obrimini in Pterobrimus depressus.

[3] A specimen collected by Daniel Otte in Naitasiri Province on Viti Levu finally confirmed Fiji as distribution of this species.

Redtenbacher chooses this name because of the rudimentary wings and the proximity of the genus to Obrimus, or more precisely to the tribe Obrimini, in which he places the species.

[3] Sarah Bank et al. were able to clarify the relationships within the family in a study on the spread of the Heteropterygidae based on genetic analysis.