The Pelecypod Family Cardiidae: A Taxonomic Summary

Abstract

The family Cardiidae is here considered to comprise six subfamilies: Cardiinae, Trachycardiinae, Fraginae, Hemidonacinae, Protocardiinae, and Laevicardiinae. The Eurasian brackish-water groups are regarded as a separate family, the Lymnocardiidae. Of 109 nominal taxa assigned to the family, 77 are accepted as useful at the generic or subgeneric levels, and one other is listed but considered of doubtful utility. The family began to emerge during late Triassic time and has radiated widely. In present-day seas cardiids are most abundant on sandy bottoms and in shallow water, although they may occur offshore in depths to 300 meters. Morphologic differences between the generic units in each of the subfamilies are summarized in dichotomous keys. Insofar as possible illustrations are of the type species for each unit, and figures of shell interiors and hinges are of left valves. A tabular summary of classification is designed to show distribution of each unit in time and space. Phylogeny of the family can be only sketchily suggested as yet, because of gaps in the fossil record. Strongest relationship seems to be to the superfamily Carditacea. Some notes on a recent review of the family by Prof. Edouard Fischer-Piette are included in an appendix. A second appendix discusses placement of two new generic units that were published by Robert Scott while this paper was in the editorial office.