A New Subgenus and Species of Petricola (Mollusca: Bivalvia) from the Pliocene of Southern Florida

Abstract

Mrs. R. C. Hoerle of West Palm Beach Florida, recently sent an unusual bivalved mollusk requesting information as to its possible systematic position. It was collected from a coral-rich faunal association that had been dredged from a drainage canal southwest of Immokalee in northern Collier County, Florida. The associated fauna in the spoil bank is thought to be predominantly of Caloosahatchee (upper Pliocene) age although a few forms suggest an upper Pinecrest (middle Pliocene) assignment. The hinge and pallial line of the species clearly reveal its relationship with the genus Petricola Lamarck, 1801, but the ornamentation is wholly different from that to be observed in that genus and, in a general way, is so mew hat reminiscent of that observed in some unionid forms. Accordingly, the species is here described as representative of a new subgenus of Petricola.