Family ASPIDISCIDAE Ehrenberg, 1838

Syn.	Paraeuplotidae

Generally small forms, with flattened, oval to rounded body; no marginal cirri, but strikingly prominent ventral group(s); reduced number of oral membranelles, located centrally and inconspicuously on ventral surface of body, with apparently no paroral membrane(s); dorsal surface often distinctly ribbed, ridged, or humped; widely distributed in variery of habitats, including echinoid gut and ascidian branchial cavity.

Aspidisca Ehrenberg, 1830 (syn. Aspidiscopsis). Very many (but < 50) species.
Euplotaspis Chatton & Séguéla, 1936. Single species.
Onychaspis Stein, 1859 (syn. of Aspidisca?). Single species,
Incertae sedis:
Paraeuplotes Wichterman, 1942. Single species.