This paper discusses the external and genital features of Polyphylla Harris as well as the taxonomic status of Polyphylla pubescens Cartwright, which was placed in the monotypic genus Polylamina Hardy. Likewise, Polyphylla pubescens is compared with Polyphylla varilosa Harris, Polyphylla annamensis (Fleutiaux), Hypothyce mixta Howden and Dinacoma caseyi Blaisdell, to assess the relationships of these taxa. Phyllophaga (Tostegoptera) lanceolata (Say) is considered the outgroup. The limited subset of characters used by Hardy to erect the genus Polylamina does not withstand the criterion of monophyly when it is assessed within the context of all available character data. Thus, new character systems relative to the external morphology of the adult and the male genitalia, are considered in this paper. Phylogenetic analysis show that ranking Polyphylla pubescens as a monotypic genus renders Polyphylla paraphyletic. Therefore, the placement of Polyphylla pubescens in the genus Polylamina is unacceptable.