Help Save America's Pearly Mussels

Authors: Louis A. Helfrich, Richard J. Neves, Diana L. Weigmann, Renee M. Speenburgh, and Braven Beaty Department of Fisheries and Wildlife Sciences Virginia Tech, and
Dick Biggins and Hilary Vinson, U.S. Fish and Wildlife Service Asheville Field Office, Asheville, North Carolina. Sponsored by U.S. Fish and Wildlife Service Asheville Field Office, Asheville, North Carolina

Publication Number 420-014, posted November 1997

Key to 10 Selected Bivalve Mollusks
of the
Ohio River Basin

Illustrations by Tim B. FisherPoff, Agricultural Research and Extension Communications, Virginia Tech

Publication Number 420-014, posted November 1997

Suggestion: This key works best when used in conjunction with Field Guide to Freshwater Mussels of the Midwest (Cummings and Mayer 1992), which is included in the mussel identification kit that is available through the U.S. Fish and Wildlife Service Asheville Field Office, Asheville, N.C., (704) 258-3939.

Shell Characters
Exterior of Right Valve Interior of Left Valve

  1. Exterior of shell D-shaped with alternating light and dark zigzag bands ; shell small, thin, and without obvious teeth (Figure 1) ... Zebra mussel (Dreissena polymorpha).

    Exterior of shell without zigzag bands, pseudocardinal teeth and lateral teeth... 2.

  1. Small serrated (sawlike) lateral teeth on both sides of the central pseudocardinal teeth; small shell with concentric ridges externally (Figure 2) ... Asian clam (Corbicula fluminea).

    Long smooth lateral teeth on only one side of pseudocardinal teeth... 3. or return to 1.

  1. Lateral teeth are poorly developed; shell thin and elongate with fluted edge. (Figure 3) ... Fluted-shell (Lasmigona costata).

    Lateral teeth well developed with two well-defined parallel lateral teeth in one of the paired shells ... 4. or return to 2.

  1. Exterior of shell with bumps, knobs, or ridges (Figure 4a) ... 5. or return to 3.

    Exterior of shell without bumps, knobs, or ridges (Figure 4b) ... 8. or return to 3.

  1. Exterior of shell with one, two, or three large bumps or knobs, the rest of the shell relatively smooth (Figure 5) ... Threehorn wartyback (Obliquaria reflexa).

    Exterior of shell with numerous bumps, or knobs, or with ridges... 6. or return to 4.

  1. Exterior of shell brown, with 3-5 long ridges (Figure 6) ... Threeridge (Amblema plicata).

    Exterior of shell with numerous bumps or knobs ... 7. or return to 5.

  1. Inside of shell (nacre) white, with pronounced posterior ridge (Figure 7) ... Monkeyface (Quadrula metanevra).

    Inside of shell purple, with weak posterior ridge (Figure 8) ... Purple wartyback (Cyclonaias tuberculata).

  1. Exterior of shell with obvious rays (Figure 9a) ... 9. or return to 4.

    Exterior of shell without obvious rays (Figure 9b) ... 10. or return to 4.

  1. Rays on exterior of shell wide, with a series of green chevron ("V" or "W") marks; posterior ridge and pointed posterior end (Figure 10) ... Deertoe (Truncilla truncata).

    Thin rays on yellow shell exterior; lines are wavy, especially towards the outer edge of the shell, rounded posterior end (Figure 11) ... Wavy-rayed lampmussel (Lampsilis fasciola).

  1. Nacre white, shell thick and heavy, rounded in shape with prominent beak (Figure 12)... Ebonyshell (Fusconaia ebena).

    Nacre purple, shell oval or elongate in shape ... 11. or return to 8.

  1. Shell small, thin, oval in outline and inflated (Figure 13) ... Lilliput (Toxolasma lividus).

    Shell elongate in outline, thick, and laterally compressed (Figure 14) ... Spike (Elliptio dilatata).

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