New York Natural Heritage Program
Brook Floater
Alasmidonta varicosa (Lamarck, 1819)
Bivalves

New York State Distribution [-]
Formerly widespread in southeastern New York, this species has disappeared from many creeks and rivers and is now extremely rare. Populations in the Housatonic and Passaic basins have apparently disappeared and in the Susquehanna River basin they have declined dramatically. Populations in the Shawangunk Kill and Delaware basin are sparse and limited in extent. Only the Neversink River population currently appears healthy (Strayer and Jirka 1997).

Global Distribution [-]
Historically found from Nova Scotia to South Carolina in Atlantic drainages. Its present distribution is spotty, especially in the south, including the Potomac drainage in Virginia, and small populations in North and South Carolina. Farther north there are some larger populations (e.g., Maine, New York) and much smaller populations in Massachusetts, Connecticut, and New Hampshire. Although A. varicosa was reported in Rhode Island over 100 years ago, there has not been a documented occurrence in the state since (Wicklow 2004).
Best Places to See
• Neversink River (Orange County)