Mactridae, common name the trough shells or duck clams, is a family of saltwater clams, marine bivalve mollusks in the order Venerida.
Description These clams have two short siphons, each with a horny sheath. The shell is shaped like a rounded-cornered equilateral triangle and there is a slight gape at the posterior. Each valve bears two cardinal teeth with four lateral teeth on the right valve and two on the left. The foot is white and wedge-shaped. They mostly inhabit the neritic zone.
Ecology Trough shells burrow in sand or fine gravel and never in muddy substrates.
Subfamilies and genera
According to the World Register of Marine Species (2025), this family contains 56 genera and is split into the following subfamilies:
Subfamily Darininae Darcinia Clark, 1946 Darina J. E. Gray, 1853
Subfamily Lutrariinae Eastonia J. E. Gray, 1853 Heterocardia Deshayes, 1855 Lutraria Lamarck, 1799 Meropesta Iredale, 1929 Standella J. E. Gray, 1853 Tresus J. E. Gray, 1853 Zenatia J. E. Gray, 1853 Zenatina Gill & Darragh, 1963
Subfamily Mactrinae Allomactra Tomlin, 1931 Austromactra Iredale, 1930 Barymactra Cossmann, 1909 Coelomactra Dall, 1895 Crassula Marwick, 1948 Cyclomactra Dall, 1895 Diaphoromactra Iredale, 1930 Harvella J. E. Gray, 1853 Huberimactra Cosel & Gofas, 2018 Leptospisula Dall, 1895 Mactra Linnaeus, 1767 Mactrella J. E. Gray, 1853 Mactrellona J. G. Marks, 1951 Mactrinula J. E. Gray, 1853 Mactromeris Conrad, 1868 Mactrotoma Dall, 1894 Maorimactra H. J. Finlay, 1928 Mulinia J. E. Gray, 1837 Oxyperas Mörch, 1853 Pseudocardium Gabb, 1866 Rangia Desmoulins, 1832 Sarmatimactra Korobkov, 1954 Scalpomactra H. J. Finlay, 1928 Scissodesma Gray, 1837 Simomactra Dall, 1894 Spisula J. E. Gray, 1837 Trinitasia Maury, 1928 Tumbeziconcha Pilsbry & Olsson, 1935 Mactrona Marwick, 1952 Petromactra Saul, 1973
Subfamily Resaniinae Resania J. E. Gray, 1853
Subfamily Tanysiphoninae Tanysiphon W. H. Benson, 1858
Incertae sedis
Aktschagylia Starobogatov, 1970 Aliomactra Stephenson, 1952 Andrussella Korobkov, 1954 Avimactra Andrusov, 1905 Caspimactra A. A. Ali-Zade & Kabakova, 1969 Chersonimactra Paramonova, 1978 Cryptomactra Andrussow, 1902 Cymbophora Gabb, 1869 Eopapyrina Woodring, 1982 Geltena Stephenson, 1946 Ionesimactra Signorelli, 2023 Kirghizella Andrusov, 1902 Mactrodesma Conrad, 1869 Mactrona Marwick, 1952 Mulinoides Olsson, 1944 Nelltia Stephenson, 1952 Nymphactra Stilwell & Zinsmeister, 1992 Ovamactra Woodring, 1982 Petromactra Saul, 1973 Planimactra Ionesi, 1986 Podolimactra Ionesi, 1986 Praerangia Cossmann, 1908 Priscomactra Stephenson, 1952 Pseudomactra Steklov, 1960 Pteroluter Saul, 1973 Stereomactra Stewart, 1930 Stiphromactra Böhm, 1929 Tenuimactra Garvie, 1996 Willimactra Saul, 1973 Zenatiopsis Tate, 1880
References
Powell A. W. B., New Zealand Mollusca, William Collins Publishers Ltd, Auckland, New Zealand 1979