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Slippershell Mussel (Alasmidonta viridis)



Slipper shell (Alasmidonta viridis), a mussel listed as Threatened in Wisconsin, is found in small to medium-sized streams with flowing hard water, sand or gravel bottoms. It is presently found only in the eastern and southern parts of Wisconsin. The known hosts are banded and mottled sculpins and johnny darter.

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 Slippershell Mussel (Alasmidonta viridis). 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 Alasmidonta viridis in the Natural Heritage Inventory Database as of July 2015.
Summary Information
State StatusTHR
Federal Status in Wisconsinnone
State RankS2
Global RankG4G5
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 rhomboid-shaped shells are light yellow, green or brown, sometimes with green rays. They have an armed hinge plate. Anterior and posterior ends are rounded. The beak sculpture consists of coarse loops with an uneven surface. The beak is swollen, but low. Pseudocardinal teeth are triangular, lateral teeth poorly developed. Beak cavity is moderately deep. One of the smallest mussels in the state at 46 mm (1.8 inches) long or less.

Habitat: Usually found buried in sand or fine gravel in shallow water or small streams. Also occurs along lakeshores on a sand bottom.

State Distribution: Occurs in the Embarrass, Little Suamico, Meeme, Mukwonago, Mullet, Pensaukee, Pigeon, and Wolf Rivers plus Kelly Brook. This species may yet be found to occur in rivers for which there are currently only historical records. See the species map.

Phenology: Johnny darter (Etheostoma nigrum) and mottled sculpin (Cottus bairdi) are host fish. They are probably infested from February through April.

Management Guidelines: Because it inhabits small streams and headwaters, this mussel is particularly vulnerable to siltation and pollution from runoff. Habitat protection and water quality improvements would benefit this species. Increased development along waterways in southeastern and northeastern Wisconsin is of great concern to the continued existence of this species.


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

Last revised: Tuesday, February 19, 2019