The special concern southern hickorynut, Obovaria jacksoniana, occurs in Missouri through southern portions of the Mississippi Interior Basin and from eastern Texas through western Alabama drainages. The Ouachita creekshell, Villosa arkansasensis, is difficult to differentiate from O. jacksoniana based on conchological characters. Since both species have been listed on conservation status, genetic divergences of both generic and species levels are important to for conservation. We used mitochondrial DNA sequences from the ND1 and COI genes for phylogenetic analysis. In addition to the 40 specimens of O. jacksoniana collected in Arkansas and Mississippi and the 21 specimens of V. arkansasensis collected in Arkansas, we also used published sequences for analysis. Phylogenetic analyses do not support monophyletic both genus of Obovaria and Villosa as both O. jacksoniana and V. arkansasensis occurred in same phylogenetic clade. Based on the phylogenetic analyses, there may be two genetic variations among O. jacksoniana, a population from east side of Mississippi River and population from west side of Mississippi River. These results suggest that species we call V. arkansasensis may be same species as O. jacksoniana and that the two populations of O. jacksoniana from east and west side of Mississippi River may be taxonomically distinct species.