The first taxonomic study of Genus Phacaspis was described in 1988 by Grootaert and Meuffels.
The result can be deduced from a stalked hypopygium of genus Phacaspis was similar to subfamily Medeterinae. But the shape of the antennae and external bristle on the posterior coxae were different with subfamily Medeterinae including they could not classify to any subfamilies in the classification of Robinson (1970); therefore genus Phacaspis was considered as incertae sedis.