The neotypification of Frontonia vernalis (Ehrenberg, 1833) Ehrenberg, 1838 and the description of Frontonia paravernalis sp. nov. trigger a critical revision of frontoniid systematics.

Green frontoniids form a monophyletic clade of freshwater organisms characterized by having a single contractile vacuole and bearing intracytoplasmatic Chlorella-like symbionts. With the neotypification of F. vernalis and F. leucas a fundamental step in Frontonia systematics was taken, and the bases for further taxonomic studies were laid.