Cyclonaias tuberculata
Purple wartyback

Key Characteristics

The purple wartyback has a roughly circular shell (to 5 inches) with numerous bumps covering about ¾ of the outside. The beak sculpture consists of numerous wavy ridges and the cavity is very deep. They have very heavy, well developed cardinal teeth and lateral teeth along the hinge. The thick and heavy shell is yellowish brown or green brown, becoming dark brown in older individuals. Nacre color ranges from white with a hint of purple to deep purple.

Status and Rank

  • State Status: T
  • State Rank: S2
  • Global Rank: G5


County NameNumber of OccurrencesYear Last Observed
St. Clair12011
St. Joseph42006
Distribution map for Cyclonaias tuberculata

Updated 5/15/2018. Information is summarized from MNFI's database of rare species and community occurrences. Data may not reflect true distribution since much of the state has not been thoroughly surveyed.


The Purple wartyback is found in medium to large rivers with gravel or mixed sand and gravel substrates.

Specific Habitat Needs

Gravel substrate needed in Mainstem Stream (3rd-4th order), Riffle, Mainstem Stream (3rd-4th order), Run, River (5th-6th order), Riffle, River (5th-6th order), Run

Natural Community Types


For each species, lists of natural communities were derived from review of the nearly 6,500 element occurrences in the MNFI database, in addition to herbarium label data for some taxa. In most cases, at least one specimen record exists for each listed natural community. For certain taxa, especially poorly collected or extirpated species of prairie and savanna habitats, natural community lists were derived from inferences from collection sites and habitat preferences in immediately adjacent states (particularly Indiana and Illinois). Natural communities are not listed for those species documented only from altered or ruderal habitats in Michigan, especially for taxa that occur in a variety of habitats outside of the state.

Natural communities are not listed in order of frequency of occurrence, but are rather derived from the full set of natural communities, organized by Ecological Group. In many cases, the general habitat descriptions should provide greater clarity and direction to the surveyor. In future versions of the Rare Species Explorer, we hope to incorporate natural community fidelity ranks for each taxon.


Like other mussels, threats are varied and include: habitat degradation, poor water quality, flow alterations, water temperature changes, heavy metals, organic pollution, sedimentation, and siltation. Maintenance or establishment of vegetated riparian buffers can help protect mussel habitats from many of these threats. Control of zebra mussels is critical to preserving native mussels. As with all mussels, fish host requirements also need to be considered.

Survey Methods

Page Citation

Michigan Natural Features Inventory. 2007. Rare Species Explorer (Web Application). Available online at [Accessed Aug 17, 2018]

More Information

See MNFI Species Abstract


Survey References

Technical References

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