White Heelsplitter

Lasmigona complanata

DIAGNOSTICS 13

SHELL

  • size: large to very large, maximum 200 mm. most under 140 mm
  • thickness: thin to moderately thick.
  • shape: overall round to oval with angular posterior. prominent dorsal wing , especially juveniles. Posterior slope margin straight. posterior ridge low and widening to squared point on many specimens, giving it a 'flat screwdriver head' look (more obvious in older specimens)
  • width: compressed
  • surface: smooth, matte. (weak corrugations on posterior slope on some specimens possible in Southern part of range, but unconfirmed in Canada)
  • beaks: project lightly above or even with hinge line. sculptures: up to 8 heavy, broken double loop bars. Deep inter-loop notch. Overall pattern resembling butterfly wings.
  • color/markings: shades of light to dark brown, faint rays when young
  • sexual dimorphism: none
  • pseudocardinal teeth: large, low, irregular
  • lateral teeth: vestigial, reduced to low oblique creases on a widened hinge plate close to beaks. prominent interdental tooth/projection low to absent .
  • nacre: white, irridescent

Soft parts: foot white

Similar species/lookalikes: large adults, living or as fresh shells, are easily identified by the large size, general shape, and white nacre. mid-sized live animals extremely similar in shape and color to younger male Pink Heelsplitter, Potamilus alatus. Beak sculptures, if not deteriorated, are then key correct identification. weathered shells also similar in general shape and size to potamilus alatus, but then easily differentiated from that taxon by the absence of lateral teeth and much larger pseudocardinals.

DISTRIBUTION/WATERSHEDS 14

ONTARIO

Lake Huron-St-Clair dr.:

  • Saugeen R.
  • Ausable R.
  • Sydenham R.
  • Thames R.

Lake Erie dr.:

  • Belle R.
  • Ruscom R.
  • Grand R.

Sources and Credits

  1. (c) Philippe Blais, some rights reserved (CC BY-NC-ND), https://www.inaturalist.org/photos/43953662
  2. (c) pagojoe, some rights reserved (CC BY-NC), http://www.inaturalist.org/photos/4660852
  3. (c) Jesse Weinzinger, some rights reserved (CC BY-NC-ND), uploaded by Philippe Blais, https://www.inaturalist.org/photos/13123318
  4. (c) Jesse Weinzinger, some rights reserved (CC BY-NC-ND), uploaded by Philippe Blais, https://www.inaturalist.org/photos/13123319
  5. (c) dbarkley, some rights reserved (CC BY-NC-ND), uploaded by Philippe Blais, https://www.inaturalist.org/photos/13123320
  6. (c) Scott LaValley, some rights reserved (CC BY-NC), https://www.inaturalist.org/photos/25395167
  7. (c) John, some rights reserved (CC BY-NC), https://www.inaturalist.org/photos/28071970
  8. (c) John, some rights reserved (CC BY-NC), https://www.inaturalist.org/photos/28071971
  9. (c) John, some rights reserved (CC BY-NC), https://www.inaturalist.org/photos/27732870
  10. (c) sadouglass, some rights reserved (CC BY-NC), https://www.inaturalist.org/photos/52611994
  11. (c) sadouglass, some rights reserved (CC BY-NC), https://www.inaturalist.org/photos/52611984
  12. (c) SWQ Staff, some rights reserved (CC BY-NC), https://www.inaturalist.org/photos/53224687
  13. (c) Philippe Blais, some rights reserved (CC BY-SA)
  14. (c) Philippe Blais, some rights reserved (CC BY-ND)

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