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Salamander Mussel (Simpsonaias ambigua)



Salamander mussel (Simpsonaias ambigua), a mussel presently listed as a Federal Species of Concern and Threatened in Wisconsin. In Wisconsin, this species is only found in mud, silt or sand substrates beneath medium to large-sized flat rocks and undercut ledges, where its host, the mudpuppy frequents. It occurs in both the Mississippi River and Lake Michigan drainages. It can be very abundant locally, but extremely rare otherwise.

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 Salamander Mussel (Simpsonaias ambigua). 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 Simpsonaias ambigua in the Natural Heritage Inventory Database as of July 2015.
Summary Information
State StatusTHR
Federal Status in WisconsinSOC
State RankS2
Global RankG3
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 yellow or brown, smooth, fragile, elongate, and thin. The anterior end is thicker than the posterior end. The male shell is less inflated than the female. Beaks are slightly elevated and somewhat pointed, directed inwardly and toward the anterior. Beak sculpture consists of three to four double-looped bars. One small pseudocardinal tooth is in each valve and the lateral teeth are indistinct. The beak cavity is shallow. The nacre is bluish-white, occasionally tinged with salmon near the beak and iridescent posteriorly. Length to 2 inches (5.1 cm).

Habitat: Found in medium to large rivers on mud or gravel bars but more common under flat slabs of rock, stones or in ledges of underwater cliff faces.

State Distribution: Occurs in the following rivers: Chippewa, Embarrass, Eau Claire, south fork of the Flambeau, Lemonweir, Mississippi, St.Croix, Wisconsin, and the Wolf.

Phenology: The salamander mussel is host specific. Glochidia have only been found on mudpuppies (Necturus maculosus) from October through May.

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. Due to the specificity of the host species, protection of mudpuppies and their habitats is particularly important.



Salamander Mussel

Photo by Lisie Kitchell, WDNR.

Last revised: Tuesday, February 19, 2019