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Purple Wartyback (Cyclonaias tuberculata)



Purple wartyback (Cyclonaias tuberculata), a mussel listed as Endangered in Wisconsin, is found in large rivers in the western and southern parts of the state. It prefers a stable substrate containing rock, gravel and sand in swift current. Known hosts include bullhead and catfish species.

State status

Status and Natural Heritage Inventory documented occurrences in Wisconsin

The table below provides information about the protected status - both state and federal - and the rank (S and G Ranks) for Purple Wartyback (Cyclonaias tuberculata). See the Working List Key for more information about abbreviations. Counties shaded blue have documented occurrences for this species in the Wisconsin Natural Heritage Inventory database. The map is provided as a general reference of where occurrences of this species meet NHI data standards and is not meant as a comprehensive map of all observations.

Note: Species recently added to the NHI Working List may temporarily have blank occurrence maps.

Documented locations of Cyclonaias tuberculata in the Natural Heritage Inventory Database as of July 2015.
Summary Information
State StatusEND
Federal Status in Wisconsinnone
State RankS2
Global RankG5
Tracked by NHIY

Species guidance

Note: a species guidance document is not available at this time. Information below was compiled from publication PUB-ER-085-99 (now out-of-print).

Identification: The shell is subrectangular, brown or black and heavy. The beak is low with a wing-like depression behind it. Beak sculpture consists of fine, irregular, broken concentric corrugations. Pseudocardinal teeth are massive and lateral teeth short and heavy. The surface of the shell is yellowish-brown to dark brown and covered with numerous rounded or elongated pustules. Nacre is purple. Length to 5 inches (12.7 cm).

Habitat: Inhabits medium sized rivers with water ranging up to five feet in slow to moderate current. Found in rocky areas with gravel and cobble substrate.

State Distribution: Occurs in the following rivers: Black, Chippewa, Flambeau, Rock, Jump, Mississippi, Namekagon and St. Croix.

Phenology: Yellow bullhead (Ameiurus natalis) and channel catfish (Ictalurus punctatus) are host fish for this species, which breeds from May through July.

Management Guidelines: 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 the purple wartyback.



Purple Wartyback

Photo by Lisie Kitchell, WDNR.

Last revised: Tuesday, February 19, 2019