Quadrula quadrula



  • size: mid-sized
  • thickness: thick
  • shape: squared in posterior, rounded in anterior; prominent but shallow sulcus anterior to the posterior ridge.
  • width: moderately inflated
  • surface: two loose rows of nodules bordering margins of sulcus, most prominent on early shell, becoming mostly smooth nearing ventral margin in adults; corrugations common on posterior slope close to beaks .
  • beaks: pointed apex curled inward/forward. sculptures: acutely lobed, tightly packed double loops forming rows of small nodule, transitioning to multiple nodules on either side of sulcus, more so in anterior.
  • color/markings: pale yellowish brown to dark brown, with faint greenish rays on juveniles
  • sexual dimorphism: none
  • pseudocardinal teeth: strong, serrated.
  • lateral teeth: low, straight
  • nacre: white

Soft parts: foot white

Similar species/lookalikes: Distinctive. The prominent sulcus bordered by two rows of nodules is diagnostic in Canadian material. Other nodulous species such as Cyclonaias tuberculata and Quadrula pustulosa don't have a wide prominent sulcus and both tend to display more numerous nodules with older shell formation. In Q. pustulosa the early shell is usually smooth, devoid of nodularities, and usually displays a broad, short green ray near the posterior part part of the beak



  • Bayfield R.
  • Ausable R.
  • Sydenham R.
  • Thames R. < McGregor Cr., Baptisite Cr.
  • Ruscom R.
  • Grand R.
  • Welland R.
  • 16 Mile Cr.
  • 20 mile Cr.

Sources and Credits

  1. (c) Philippe Blais, some rights reserved (CC BY-NC-ND),
  2. (c) redgarter, some rights reserved (CC BY-NC-ND), uploaded by Philippe Blais,
  3. (c) Will Van Hemessen, some rights reserved (CC BY-NC),
  4. (c) Cindy Jones, some rights reserved (CC BY-NC),
  5. (c) nr_travis, some rights reserved (CC BY-NC),
  6. (c) nr_travis, some rights reserved (CC BY-NC),
  7. (c) Cindy Jones, some rights reserved (CC BY-NC),
  8. (c) Scott Gibson, some rights reserved (CC BY-NC),
  9. (c) keith_lott, some rights reserved (CC BY-NC),
  10. (c) Blake A. Mann, some rights reserved (CC BY-NC),
  11. (c) m_ignoffo, some rights reserved (CC BY-NC),
  12. (c) Philippe Blais, some rights reserved (CC BY-NC-ND),
  13. (c) Colin Murray, some rights reserved (CC BY-NC),
  14. Adapted by Philippe Blais from a work by (c) Wikipedia, some rights reserved (CC BY-SA),
  15. (c) Philippe Blais, some rights reserved (CC BY-SA)

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