Belongs within: Ambleminae.
Epioblasma is a genus of North American freshwater mussels, most of which are now severely endangered, several recently becoming extinct.
Characters (from Smith 2001): Shell usually less than 60 mm in length, posterior half sulcate or with one or two radiating ridges, sometimes with fine wrinkles or costae; sexual dimorphism strongly pronounced; mantle of female in front of inhalant aperture forming a broad thick lobe, inner edge papillate.
Epioblasma
|--E. florentina [=Dysnomia florentina]USDI77
| |--E. f. florentinaUSDI77
| `--E. f. curtisi [=Dysnomia florentina curtisi]USDI77
|--E. sampsoni [=Dysnomia sampsoni]USDI77
|--E. sulcata [=Dysnomia sulcata]USDI77
| |--E. s. sulcataUSDI77
| `--E. s. delicata [=Dysnomia sulcata delicata; incl. E. perobliqua]USDI77
|--E. torulosa [=Dysnomia torulosa]USDI77
| |--E. t. torulosaUSDI77
| |--E. t. gubernaculum [=Dysnomia torulosa gubernaculum]USDI77
| `--E. t. rangianaPC11
`--E. turgidula [=Dysnomia turgidula]USDI77
*Type species of generic name indicated
References
[PC11] Plazzi, F., A. Ceregato, M. Taviani & M. Passamonti. 2011. A molecular phylogeny of bivalve mollusks: ancient radiations and divergences as revealed by mitochondrial genes. PLoS One 6 (11): e27147.
Smith, D. G. 2001. Pennak’s Freshwater Invertebrates of the United States: Porifera to Crustacea 4th edition. John Wiley and Sones.
[USDI77] USDI (United States Department of the Interior). 1977. Endangered and threatened wildlife and plants—republication of list of species. Federal Register 42: 36420–36431.