New York Natural Heritage Program
Dwarf Wedgemussel
Alasmidonta heterodon (I. Lea, 1830)
Alasmidonta heterodon Kathryn J. Schneider
Family: Unionid Mussels (Unionidae)

State Protection: Endangered
A native species in imminent danger of extirpation or extinction in New York (includes any species listed as federally Endangered by the United States). It is illegal to take, import, transport, possess, or sell an animal listed as Endangered, or its parts, without a permit from NYSDEC. 1) Any native species in imminent danger of extirpation or extinction in New York. 2) Any species listed as endangered by the United States Department of the Interior.

Federal Protection: Endangered
Listed as Endangered in the United States by the US Department of Interior.

State Rarity Rank: S1
A State Rarity Rank of S1 means: Typically 5 or fewer occurrences, very few remaining individuals, acres, or miles of stream, or some factor of its biology makes it especially vulnerable in New York State.

Global Rarity Rank: G1G2
A Global Rarity Rank of G1G2 means: Critically Imperiled or Imperiled globally - At very high or high risk of extinction due to rarity or other factors; typically 20 or fewer populations or locations in the world, very few individuals, very restricted range, few remaining acres (or miles of stream), and/or steep declines. More information is needed to assign a single conservation status.

Did you know?
The Neversink River population, estimated at 20,000 individuals is one of the largest known populations in the U.S. (Strayer and Jirka, 1997).

State Ranking Justification [-]
The extent of this species in New York is limited to a small area within the Delaware River watershed. The Neversink River population, a tributary of the Delaware, dropped by an estimated 60,000 individuals between 1990 to 1994 and continues to be vulnerable to a myraid of stressors that affect aquatic systems, including non-point pollution and existing impoundments (Strayer et al. 1996).

Short-term Trends [-]

Long-term Trends [-]