Endangered Resources Program Species Information
Buckhorn (Tritogonia verrucosa)

Overview

Species Overview

Buckhorn (Tritogonia verrucosa),a mussel listed as Threatened in Wisconsin, is found in medium to large-sized rivers, with a moderate to swift current, and clean, firm substrates. The known host fish are yellow and brown bullheads and flathead catfish.

Status and NHI Documented Occurrences in Wisconsin

The table below provides information about the protected status (State and Federal Status) and the rank (S and G Ranks) for Buckhorn (Tritogonia verrucosa). See the Working List Key for more information about the abbreviations used. Counties shaded blue have documented occurrences for this species in the Wisconsin Natural Heritage Inventory database. For invertebrates, dots depict locations from the "Invertebrate Atlas," a database with occurrences of rare and common aquatic and select terrestrial invertebrate species found in Wisconsin and adjacent areas. While the invertebrate atlas is a quality assured database, not all records have been verified. The map is provided as a general reference of where this species has been found to date and is not meant as a range map.

Summary Information State Status: THR Federal Status in Wisconsin: none State Rank: S2 Global Rank: G4G5 Tracked by NHI: Y Species of Greatest Conservation Need: Y

Detailed Information

Identification: The elongate shell is brown or black, moderately large, heavy, and has many pustules. Low umbo. Beak sculpture consisting of a series of ridges continuing down the side. Pseudocardinal teeth are heavy and serrated and the lateral teeth are long, straight and striated. Ventral margin usually arched. Beak cavity deep. The nacre is white and posteriorly iridescent. The female shell has larger wing-like extensions, which the males lack. Length to 8 inches (20.3 cm).

Habitat: Inhabits fairly deep water on a sand or mud bottom. Also found in riffles and in shallow water (1-3 m) of smaller streams.

State Distribution: Occurs in the following rivers: the Mississippi, the Black, the upper and lower Wisconsin, the White, the St. Croix, the Baraboo, the Chippewa, the Eau Claire, the Pecatonica, and the Wolf.

Phenology: The breeding season lasts from April to July. The brown bullhead (Ameiurus nebulosus), yellow bullhead (Ameiurus natalis), and flathead catfish (Pylodictis olivaris) are known hosts.

Management Guidance: Habitat destruction and river pollution have resulted in mussel declines. Protection of habitat and improvements in water quality along with restriction of dredging, impoundments, sand and gravel mining, and navigational improvements would benefit this species. The development of fish runways to facilitate the movement of host species through or around dams could also help to protect this species.

Information compiled from publication PUB-ER-085-99 (now out-of-print).

Photos

Click on a photo to view a larger version. Please considering donating your photos to the Endangered Resources Program for educational uses. See also information regarding use of photos

Photo by Lisie Kitchell, WDNR.

Related Links

Links to Additional Buckhorn Information

• MN Department of Natural Resources [Exit DNR]
• Illinois Natural History Survey [Exit DNR]

Other Links Related to Mussels and Clams

• Illinois Natural History Survey [Exit DNR]
• The Field Museum [Exit DNR]
• Conchologists of America [Exit DNR]
• EPA Biological Indicators of Watershed Health [Exit DNR]
• Milwaukee Public Museum [Exit DNR]