Unionidae, Rafinesque, 1820

Jindal, Rajinder & Wats, Meenu, 2021, Systematic descriptions and seasonal variations of mollusc in Chandigarh (U. T., India) and its surrounding freshwater bodies, International Journal of Fisheries and Aquatic Studies 9 (3), pp. 165-173 : 169-170

Family: Unionidae

Unionidae family is commonly referred as pearly mussels or unionids, and are found in freshwater habitats globally. These bivalves are the inhabitants of permanent freshwater sources like lakes, streams and rivers. The shells of this family are internally nacreous having equilateral valves with raised umbones and well developed radial sculptures. They are the key members of aquatic ecosystems and plays very vital ecological role like nutrient cycling, bio-turbation, water purification etc.

Lamellidens marginalis (Lamarck, 1819)

Taxonomic description- Shell oblong-ovate, twice as long as high, thin, smooth, somewhat inflated, inner surface of shell pearly and iridescent; periostracum blackish-brown and shinning; valves equilateral; umbones placed nearer to anterior end; dorsal margin behind the umbones almost straight, extends into a more or less well defined wing expansion; anterior margin narrower than posterior margin, anterior end evenly rounded; ventral margin slightly contracted in the middle; right valve with hinge with two cardinals, upper one poorly developed, a single lateral and a trace of second one;

left valve with one cardinal and two curved lateral teeth; adductor impression and non-sinuate pallial line typical.

Lamellidens corrianus (Lea, 1834)

Taxonomic description- Shell narrowly elliptical, longer in proportions to height; valves equilateral, relatively thin; umbones slightly inflated; periostracum smooth, dark or greenish brown; anterior margin rounded, posterior margin more or less sub-angular; posterior wing expansion thin, ventral margin evenly curved; cardinal teeth thin, lamina like, two in each valve or one in left and two in right valve; lateral teeth elongated, thin, straight; nacre bluish white or pearly white and iridescent; adductor scars and pallial line fairly marked.

Parreysia caerulea (Lea, 1831)

Taxonomic description- Shell elongate, internally nacreous, sculpture restricted to the upper half of the valves in the adult, young shells with whole shell surface sculptured; posterior umbonal carina very distinct.