Flutedshell
Lasmigona costata
Diagnostics 3
SHELL
- size: mid-sized to large, maximum 175 mm, but most under 130 mm
- thickness: thin to moderately thick
- shape: oval to trapezoidal, with posterior end often much higher than front. posterior ridge usually well defined. squared posterior margin common.
- width: compressed to moderately compressed. widest in posterior
- surface: smooth except corrugations on posterior ridge, from pronounced to very discreet, more rarely entirely absent. mid-shell creases common.
- beaks: low. sculptures 3 to 4 heavy double-looped bars, progressively shifted posteriorly, creating uneven spacing in between. often dissolved/eroded.
- color/markings: greenish to brown, with numerous fine green rays in younger specimens
- sexual dimorphism: none
- pseudocardinal teeth: moderately developed, weakly protruding from hinge line. Largest tooth is single in right valve, which fits in depression in front of smaller back tooth in left valve. left front tooth usually absent or rudimentary.
- lateral teeth: vestigial, reduced to low oblique creases on a widened hinge plate close to beaks. prominent interdental tooth/projection common
- nacre: white with a salmon, tan or gold flush in the cavity.
Soft parts: foot white or beige. mantle uniformly dark, inhalant aperture long and narrow, with even margin. exhalent aperture very long and narrow with short papillae
Similar species/lookalikes: average size and shell thickness greatly influenced by water quality and hardness. the combination of posterior slope corrugations, interdental projection and absence of lateral teeth are diagnostic, making identification of most live specimens or shells straightforward. Live specimens without clear corrugations can easily be confused with some variants of Elliptio complanata.
Sources and Credits
- (c) Philippe Blais, some rights reserved (CC BY-NC-ND), uploaded by Philippe Blais
- (c) Matthew Ireland, all rights reserved, uploaded by Matthew Ireland
- Adapted by Philippe Blais from a work by (c) Wikipedia, some rights reserved (CC BY-SA), http://en.wikipedia.org/wiki/Lasmigona_costata
