Purple Wartyback

Cyclonaias tuberculata

Diagnostics 5


  • size: large to very large
  • thickness: moderately thick to very thick
  • shape: round or oval to quadrate
  • width: compressed in young to moderately inflated as adults
  • surface: disk more or less densely covered with prominent nodules except front 1/4
  • beaks: prominent, flat and strongly curled/folded inwards. Sculptures: tightly packed and numerous double or triple looped fine ridges with a row of small nodules towards posterior.
  • color/markings: uniformly pale to dark brown. greenish-brown when very young.
  • sexual dymorphism: none
  • pseudocardinal teeth: massive and serrated, molar-like. One in left valve and three in right.
  • lateral teeth: short and thick. interdentum very wide over very deep beak cavity
  • nacre: uniformly deep purple. cavity inside palial line occasionally paler purple, pink, or white inside. palial margin very wide in anterior

Soft parts: foot whit

Similar species/lookalikes: Pimpleback has less numerous or prominent nodules, is smaller overall and always has entirely white nacre. Young specimens also have at least one distinct, broad green ray near the beak in posterior, whereas the Purple Wartyback is devoid of any significant raying. Beaks of Pimpleback without any distinct sculpturing, and only slightly curled.
Mapleleaf also has an entirely white nacre but also fewer nodules, and always has a shallow but wide sulcus anterior to the posterior ridge that is usually nodule free.
Combination of purple nacre with nodulous disc is diagnostic for the species in Canada

Sources and Credits

  1. (c) Philippe Blais, some rights reserved (CC BY-NC-ND), https://www.inaturalist.org/photos/43953286
  2. (c) Philippe Blais, some rights reserved (CC BY-NC-ND), https://www.inaturalist.org/photos/43953302
  3. (c) Philippe Blais, some rights reserved (CC BY-NC-ND), https://www.inaturalist.org/photos/44169104
  4. (c) Philippe Blais, some rights reserved (CC BY-NC-ND), https://www.inaturalist.org/photos/44169117
  5. Adapted by Philippe Blais from a work by (c) Wikipedia, some rights reserved (CC BY-SA), http://en.wikipedia.org/wiki/Cyclonaias_tuberculata

More Info

iNatCA Map