On September 7, 2021, we proposed adding the pyramid pigtoe (Pleurobema rubrum, also known as the pink pigtoe), to the federal list of threatened and endangered species, as threatened (Read the proposal). On March 26, 2024 we withdrew that proposal, a decision based on new genetic research demonstrating that the pyramid pigtoe is not a distinct species (Read the withdrawal). 


In 2010, the Service was petitioned to place the pyramid pigtoe mussel on the federal list of theatened and endangered species. It was one of 404 species petitioned at the time by a handful of organizations. After reviewing the petition, in 2011 we found the petition presented substantial information indicating that listing the pyramid pigtoe may be warranted. That finding triggered a deeper examination of the data available, culminating in its proposed listing under the Endangered Species Act. Subsequent genetic research revealed the pyramid pigote is not a distinct species, but rather is the same animal as the more common round pigtoe (Read the article here - this is not a Service website and the Service is not responsible for its contents).

Public participation

The public comment period for this proposal was September 3 - November 8, 2021.

About the pyramid pigtoe

Today, the mussel is known to be in Alabama, Arkansas, Kentucky, Louisiana, Mississippi, Ohio, Oklahoma, Tennessee and Virginia. It has disappeared from Illinois, Indiana, Iowa, Kansas, Minnesota, Missouri, Pennsylvania, West Virginia and Wisconsin.

The pyramid pigtoe grows up to 3.6 inches long and may live up to 45 years. It lives in medium to large rivers, preferring a mixture of sand, gravel and cobble stream bottoms. It has suffered negative impacts from influences common to central U.S. streams, including habitat fragmentation from dams and other barriers, habitat loss, degraded water quality from chemical contamination and erosion, direct mortality from dredging and harvest, and the proliferation of invasive species invasive species
An invasive species is any plant or animal that has spread or been introduced into a new area where they are, or could, cause harm to the environment, economy, or human, animal, or plant health. Their unwelcome presence can destroy ecosystems and cost millions of dollars.

Learn more about invasive species
, such as the zebra mussel, Asian clam and black carp.

Contact Information



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Serving western North Carolina and southern Appalachia by conserving our most imperiled species and working with federal agencies to conserve plants, fish, and wildlife.