Snuffbox
Epioblasma triquetra
DIAGNOSTICS 10
SHELL
- size: small to mid-sized
- thickness: thick
- shape: triangular; pronounced posterior ridge; posterior slope flat, wide and in same plane as opposing side
- width: inflated to very inflated
- surface: smooth except for finely ribbed posterior slope, and rows of small bumps on posterior ridge in mature females
- beaks: elevated, wide; sculptures: few faint double-looped bars
- color/markings: yellowish with dense, broken deep green rays or chevrons with downward-pointing triangular ends
- sexual dimorphism: pronounced: Males more compact, less inflated and grow larger than females; posterior end more pointed in females and truncated look of posterior slopes also more pronounced; pointed posterior end's edge has minute teeth in mature females; females appear almost circular from axial/posterior view
- pseudocardinal teeth: large; posterior tooth on left valve upturned
- lateral teeth: short, thick
- nacre: white
Soft parts: -------
Similar species/lookalikes: Downward pointing triangular markings are diagnostic in Canada, but are more evident in older animals. Immature specimens can resemble adult Truncilla donaciformis, but that species usually has upward pointing triangular or arrow-shaped markings, not downward pointing.
Shape is very similar to Alasmidonta marginata, but that species has small dark dots on shell, never triangular markings. Also, presence of well developed pseudocardinals and lateral teeth would rule out that species in very weathered shell specimens in which periostracum markings are fared or eroded away.
DISTRIBUTION/WATERSHEDS 11
ONTARIO
Lake Huron-St-Clair dr.:
- Sydenham R.
Thames R.
Lake Erie dr.:- Grand R.
Sources and Credits
- (c) Philippe Blais, some rights reserved (CC BY-NC-ND), uploaded by Philippe Blais
- (c) Smithsonian Institution, National Museum of Natural History, Department of Invertebrate Zoology, some rights reserved (CC BY-NC-SA), https://collections.nmnh.si.edu/services/media.php?env=iz&irn=24840
- (c) Tim Lane, some rights reserved (CC BY-NC-ND), https://www.flickr.com/photos/119210184@N05/12941134324/
- (c) Rob Curtis, some rights reserved (CC BY-NC-SA), uploaded by Rob Curtis
- (c) Scott Gibson, some rights reserved (CC BY-NC), uploaded by Scott Gibson
- (c) ColinDJones, some rights reserved (CC BY-NC), uploaded by ColinDJones
- (c) Matthew Ireland, all rights reserved, uploaded by Matthew Ireland
- (c) Tim Lane, some rights reserved (CC BY-NC-ND), https://www.flickr.com/photos/119210184@N05/12897747734/
- (c) Michael L. Buntin, some rights reserved (CC BY-NC), uploaded by Michael L. Buntin
- Adapted by Philippe Blais from a work by (c) Wikipedia, some rights reserved (CC BY-SA), http://en.wikipedia.org/wiki/Epioblasma_triquetra
- (c) Philippe Blais, some rights reserved (CC BY-SA)
