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Wartyback (Quadrula nodulata)



Wartyback (Quadrula nodulata), a mussel listed as Threatened in Wisconsin, is found in large rivers in sand, mud, or fine gravel. It can be locally common. Six common host fishes have been reported, including crappie, bluegill, catfish, and bass 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 Wartyback (Quadrula nodulata). 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 Quadrula nodulata in the Natural Heritage Inventory Database as of July 2015.
Summary Information
State StatusTHR
Federal Status in Wisconsinnone
State RankS1S2
Global RankG4
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: Shell is brown or yellow, small, and heavy. Beak includes a few tubercles that extend onto the disc to the ventral margin in two diverging rows with no depression between them. Pseudocardinal teeth are serrated and heavy. Lateral teeth are serrated, short, heavy and straight. Nacre is pearly white and iridescent posteriorly. Anterior end is sharply rounded and the posterior end is sharply truncated, slightly winged or alate. Length to 3 inches (7.6 cm).

Habitat: Found in large rivers where it usually lives in sand or fine gravel. Juvenile shells often found on sandbars.

State Distribution: Occurs in the Mississippi and lower Wisconsin Rivers.

Phenology: Host fish for this species are known to be black crappie (Pomoxis nigromaculatus), white crappie (P.annularis), bluegill (Lepomis macrochirus), largemouth bass (Micropterus salmoides), and channel catfish (Ictalurus punctatus). Glochidia have been found on white crappie in September.

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


No additional photos are available for Wartyback at this time. Please consider donating a photo to the Natural Heritage Conservation program.

Last revised: Tuesday, February 19, 2019