Fatmucket

Lampsilis siliquoidea

DIAGNOSTICS 15

SHELL

  • size: mid-sized to large; maximum 155 mm, most specimens under 70 mm
  • thickness: moderately thick
  • shape: oval to long-elliptical; posterior ridge subtle, relatively straight in males, less obvious and often curved downwards in females
  • width: moderately compressed to very inflated, old animals becoming almost round in cross-section
  • surface: relatively smooth, occasionally shiny
  • color/markings: periostracum yellowish to brown, or burgundy; irregularly distributed fine green rays is most common, but very variable (from none to heavy and/or crowded green rays)
  • beaks: swollen, situated at anterior third of shell; extend slightly above hinge line; sculptures: many crowded, double-looped bars; beak cavity moderately deep.
  • sexual dimorphism: usually obvious; posterior end rounded in females, more so around marsupial area (often pronounced in older females), more pointed in males; adult females commonly much higher in profile in posterior than anterior
  • pseudocardinal teeth: medium-sized, usually more compressed in adult females than males
  • lateral teeth: well developed, narrow and thin
  • nacre: white or pink, or variable combination of those colors.

Soft parts: foot white; female mantle lure variable: small "minnow-mimic" or "shrimp-mimic" with eye-spots and fringed "tail" is most common, "worm-mimic" and "arthropod-mimic" much rarer; mantle flaps marbled, brindled or spotted, and smooth (devoid of papillae); swollen marsupium usually pale gray or blotched white and very visible between gaping mantle flaps, often protruding significantly; active luring is diurnal, and luring females barely emerge from substrate and commonly positioned obliquely.

Similar species/lookalikes: Due to the very variable nature of most of it's identification criteria, this species is very similar to and often a challenge to positively distinguish from L. radiata in the field, and vice-versa. Female lure features might be more useful identification criteria than shell features, but only observable in actively luring, undisturbed in-situ animals. (see description of L. radiata), but more research is needed to shed light on this matter.
Large and compact males can resemble medium-sized Lampsilis cardium.

IMPORTANT NOTE: The taxonomy of L. radiata and L. siliquoidea is still murky. Further genetic studies could possibly lead to more precise respective diagnostic criteria. Hybridization and important range overlaps further complicate this situation. All identification features described above may therefore need to be partially or entirely revised in the future.

Sources and Credits

  1. (c) Jesse Weinzinger, some rights reserved (CC BY-NC), http://www.inaturalist.org/photos/3823487
  2. (c) tlev, some rights reserved (CC BY-NC), https://www.inaturalist.org/photos/30014963
  3. (c) pagojoe, some rights reserved (CC BY-NC), http://www.inaturalist.org/photos/4538839
  4. (c) Philippe Blais, some rights reserved (CC BY-NC-ND), https://www.inaturalist.org/photos/56883792
  5. (c) Matthew Ireland, some rights reserved (CC BY-NC), http://inaturalist.ca/photos/9210132
  6. (c) Matthew Ireland, some rights reserved (CC BY-NC), http://inaturalist.ca/photos/7597924
  7. (c) Philippe Blais, some rights reserved (CC BY-NC-ND), https://www.inaturalist.org/photos/56784355
  8. (c) Philippe Blais, some rights reserved (CC BY-NC-ND), https://www.inaturalist.org/photos/56834945
  9. (c) Philippe Blais, some rights reserved (CC BY-NC-ND), https://www.inaturalist.org/photos/56834926
  10. (c) Philippe Blais, some rights reserved (CC BY-NC-ND), https://www.inaturalist.org/photos/56784633
  11. (c) Philippe Blais, some rights reserved (CC BY-NC-ND), https://www.inaturalist.org/photos/56784309
  12. (c) redgarter, some rights reserved (CC BY-NC-SA), uploaded by Philippe Blais, https://www.inaturalist.org/photos/57598541
  13. (c) redgarter, some rights reserved (CC BY-NC-SA), uploaded by Philippe Blais, https://www.inaturalist.org/photos/57598543
  14. (c) redgarter, some rights reserved (CC BY-NC-SA), uploaded by Philippe Blais, https://www.inaturalist.org/photos/57598545
  15. Adapted by Philippe Blais from a work by (c) Wikipedia, some rights reserved (CC BY-SA), http://en.wikipedia.org/wiki/Lampsilis_siliquoidea

More Info

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