What, if anything, is Cyprideis multidentata Hartmann, 1955 (Ostracoda: Crustacea)?

The species Cyprideis riograndensis Pinto & Ornellas is considered by some authors a junior synonym to Cyprideis multidentata Hartmann. A restudy of the type-series of the former, as well as the analysis of living and fossil specimens from the northern Rio Grande do Sul coastal plain, however, demonstrated significant morphological differences between both species. This study sustains the validity of C. riograndensis and the necessity of reevaluating C. multidentata. Keywords: Brazil, curatorship, Cyprideis riograndensis, paleontological species concept, systematics.