Eastern Lampmussel
Lampsilis radiata
DIAGNOSTICS 2
SHELL
- size: mid-sized to large; maximum 150 mm, most specimens under 80 mm
- thickness: moderately thick
- shape: oval to elliptical; posterior ridge subtle, relatively straight in males, less obvious and often curved ventrally in females
- width: moderately compressed to very inflated, old animals becoming almost round in cross-section
- surface: relatively smooth, usually matte
- color/markings: periostracum pale yellowish-green to brown or burgundy; dense, blurred and dark green rays is most common, but very variable (from few to heavy and/or crowded green rays)
- beaks: swollen, situated at anterior third of shell; extend slightly above hinge line; sculptures: few, crowded, double-looped bars
- 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; beak cavity moderately deep
- lateral teeth: well developed, narrow and thin
- nacre: white or pink, or variable combination of both.
Soft parts: foot white; female mantle lure variable: wide, wrinkled/papillate curtain-like flaps that don't protrude much away from shell edges, with obliquely protruding "rat-tails" of variable length at anterior-lower end of lure (crossing at their base); eye-spot usually absent: mantle flaps very variable in color: marbled dark to light gray more common, but can be rusty-brown or white or combinations of these colors. Swollen marsupium usually very dark, and mostly hidden my mantle flaps. Active luring is diurnal, and luring females are usually well emerged from substrate and positioned vertically while luring.
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. silliquoidea 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. silliquoidea), but more filed data and 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
- (c) Philippe Blais, some rights reserved (CC BY-NC-ND), uploaded by Philippe Blais
- (c) Philippe Blais, some rights reserved (CC BY-SA)
