Creek Heelsplitter

Lasmigona compressa

DIAGNOSTICS 7

SHELL

  • size: mid-sized, maximum 120 mm, most under 100 mm.
  • thickness: thin to moderately thick
  • shape: trapezoidal to oval, with small dorsal wing (more pronounced in young). Posterior ridge widening to distinct squaring at shell edge, giving it a "flat screwdriver tip" look.
  • width: compressed
  • surface: smooth. mid-shell radial creases common
  • beaks: slightly elevated. sculpture: 5 to 8 irregular/angular double loop ridges
  • color/markings: periostracum straw yellow to dark brown, with green rays progressively more dense towards posterior where they merge to give a dominant green color.
  • sexual dimorphism: none (hermaphroditic)
  • pseudocardinal teeth: small, flat/compressed
  • lateral teeth: small but well developed, with a prominent inter-dental projection in left valve
  • nacre: white, commonly with a salmon flush in beak cavity

Soft parts: foot bright orange, more rarely white or peach.

Similar species/lookalikes: young live specimens can resemble small Lasmigona complanata, but that taxon usually has much more pronounced posterior wings as juveniles, periostracum is darker, and raying is weak or absent. Live adults can have a similar shape as L. costata in which fluting is very reduced. In such specimens beak sculptures - when present - are very different (few, heavy double-loob bars in L. costata). Shell specimens, even incomplete, are easily identifiable by the combination of inter-dental projection and well developed lateral teeth, which is diagnostic for the species.

Sources and Credits

  1. (c) Philippe Blais, some rights reserved (CC BY-NC-ND), https://www.inaturalist.org/photos/35155392
  2. (c) redgarter, some rights reserved (CC BY-NC-ND), uploaded by Philippe Blais, https://www.inaturalist.org/photos/12816358
  3. (c) redgarter, some rights reserved (CC BY-NC-ND), uploaded by Philippe Blais, https://www.inaturalist.org/photos/12327881
  4. (c) redgarter, some rights reserved (CC BY-NC-ND), uploaded by Philippe Blais, https://www.inaturalist.org/photos/12406723
  5. (c) Matthew Ireland, some rights reserved (CC BY-NC), http://inaturalist.ca/photos/7598097
  6. (c) Philippe Blais, some rights reserved (CC BY-NC-ND), https://www.inaturalist.org/photos/11322170
  7. Adapted by Philippe Blais from a work by (c) Wikipedia, some rights reserved (CC BY-SA), http://en.wikipedia.org/wiki/Lasmigona_compressa

More Info

iNatCA Map