Black Sandshell

Ligumia recta

DIAGNOSTICS 10

SHELL

  • size: large, up to 200 mm, most specimens under 150 mm
  • thickness: moderate to very thick depending on water hardness.
  • shape: moderately to very elongate.
  • width: moderately inflated
  • surface: smooth, often with cloth-like fine wrinkles along creases radiating from beaks
  • beak: low and very anterior, sculpture 3-5 indistinct double-loop bars, usually dissolved/eroded
  • color/markings: uneven dark green rays on yellowish to greenish background. Older adults often entirely black and rayless
  • sexual dimorphism: pronounced: distinct and curved widening of inferior-posterior edge in marsupial area in female, making back end of shell higher than front, the opposite of those same proportions in males.
  • pseudocardinal teeth: well developped, mid-sized
  • lateral teeth: well developed
  • nacre: uniformly white, but beak cavity commonly with pink or purple flush. more rarely uniformly pink or purple.

Soft parts: foot white; mantle dark grey or black; female lure (hellgrammite mimic): very long and wide extension of mantle with fringe of long cirri; inner mantle rusty orange marbled with dark radial streaks; eye-spot usually present at posterior end of lure; lure color may vary, with pale grey and all white being rarer.

Similar species/lookalikes: Small specimens might be confused with Elliptio dilatata (spike), but that species lacks pronounced rays and color is usually shades of brown, more rarely green, has a thicker shell, and has shorter lateral teeth which are thicker and of unequal length in the left valve. No other Canadian native species is as elongate except for Ligumia nasuta which has a distinct, more sharply angled posterior margin.

DISTRIBUTION/WATERSHEDS 11

MANITOBA

  • Red River dr.
  • Winnipeg River dr.

ONTARIO
Lake Huron-Lake St-Clair Dr.:

  • Ausable R.
  • Ruscom R.

Lake Erie dr.:

  • Sydenham R.
  • Thames R.
  • Grand R.
    Lake Ontario Dr.

  • Moira R.
  • Salmon R.

QUEBEC

Saint-Lawrence River dr.

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-

Ottawa River dr.:

-

-

-

Sources and Credits

  1. (c) redgarter, some rights reserved (CC BY-NC-ND), uploaded by Philippe Blais, https://www.inaturalist.org/photos/5939236
  2. (c) Philippe Blais, some rights reserved (CC BY-NC-ND), https://www.inaturalist.org/photos/9739954
  3. (c) P. Blais, some rights reserved (CC BY-NC-ND), uploaded by Philippe Blais, https://www.inaturalist.org/photos/32031081
  4. (c) Philippe Blais, some rights reserved (CC BY-NC-ND), https://www.inaturalist.org/photos/11322166
  5. (c) P. Blais, some rights reserved (CC BY-NC-ND), uploaded by Philippe Blais, https://www.inaturalist.org/photos/32031077
  6. (c) Matthew Ireland, some rights reserved (CC BY-NC), http://inaturalist.ca/photos/7691384
  7. (c) redgarter, some rights reserved (CC BY-NC-ND), uploaded by Philippe Blais, https://www.inaturalist.org/photos/13042666
  8. (c) redgarter, some rights reserved (CC BY-NC-ND), uploaded by Philippe Blais, https://www.inaturalist.org/photos/13042667
  9. (c) redgarter, some rights reserved (CC BY-NC-ND), uploaded by Philippe Blais, https://www.inaturalist.org/photos/13042832
  10. Adapted by Philippe Blais from a work by (c) Wikipedia, some rights reserved (CC BY-SA), http://en.wikipedia.org/wiki/Ligumia_recta
  11. (c) Philippe Blais, some rights reserved (CC BY-ND)

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