Cardiidae (Mollusca: Bivalvia) from the Chipola Formation, Calhoun County, Florida

Abstract

Fifteen species of cardiid bivalves are reported from the type area of the Chipola Formation in Calhoun County, Florida.  These 15 species are assigned to nine genera and four subfamilies; one new subgenus, Trachycardium (Conilocardium) type species "Cardium (Trachycardium)" cestum Dall - and five new species: Acrosterigma (Vasticardium) hoerleorum, Papyridea miocica, Papyridea multicostula, Fragum tunicula, and Trigoniocardia (Americardia) decidua are described.  More than 40,000 valves were examined during the study, with slightly more than one-third of these proving to be referrable to Trigoniocardia (Trigoniocardia) simrothi (Dall).  This species together with Dinocardiurn chipolanum (Dall) and Trigoniocardia (Trigoniocardia?) burnsii (Dall) constitute almost three-fourths of the cardiid fauna.  Variation in the distribution of some of the species poses problems, probably of ecologic nature, that at present cannot satisfactorily be resolved; others appear to be of possible time/ stratigraphic significance.  Use of long-wave ultraviolet light has permitted the study of latent color patterns on a number of the species; these have been of much use in confirming their generic identification.