Illinois Natural History Survey - University of Illinois

Epioblasma torulosa (Rafinesque, 1820)

Tubercled blossom


 

Epioblasma torulosa, UIMNH Z-3947Epioblasma torulosa, UIMNH Z-3947. Tennessee River, Lauderdale County, Alabama. 
Length: 2.2 inches (5.6 cm) for male (top), 2.1 inches (5.3 cm) for female (bottom).

Other common names None.Epioblasma torulosa distribution

Key characters Males and females yellowish brown with green rays but much different in shape. Males oblong with a sulcus running along the posterior ridge from the umbo to the ventral margin. Females with a large expanded posterior end. Both with a series of enlarged knobs running from the beaks and continuing to the posterior-ventral margin.

Similar species Northern riffleshellsheepnose,threehorn wartyback.

Description Shell thick anteriorly, much thinner posteriorly, elongate, and inflated. Anterior margin rounded, posterior-ventral margin broadly rounded or slightly truncated in females, indented in males. Umbos low, somewhat turned forward. Beak sculpture of two or three indistinct ridges, evident only in very young shells. A row of large tubercles or knobs running from the beaks and continuing to the posterior-ventral margin. A wide, shallow sulcus or depression present between the row of knobs and the posterior ridge. Periostracum yellowish brown with numerous fine green rays, obscure in older shells. Length to 3 inches (7.6 cm).

Pseudocardinal teeth triangular, divergent, and roughened; two in the left valve, one in the right with two smaller teeth on either side. Lateral teeth short, straight and roughened; two in the left valve, one in the right with a much smaller tooth below. Beak cavity moderate to shallow. Nacre white, iridescent posteriorly.

Habitat Medium to large rivers in gravel riffles.

Status Federally Endangered. Extirpated from the Midwest.


Back Forward Species | Table of Contents



Illinois Natural History Survey

1816 South Oak Street, MC 652
Champaign, IL 61820
217-333-6880
cms@inhs.illinois.edu

Terms of use. Email the Web Administrator with questions or comments.

© 2019 University of Illinois Board of Trustees. All rights reserved.
For permissions information, contact the Illinois Natural History Survey.

Staff Intranet
Login