New occurrences of crabs (Decapoda, brachyura, eubrachyura) in the pliocene of florida (United States)

Abstract

Despite the rich fossil record of decapod crustaceans in Florida, there are still several stratigraphic intervals for which almost no fossil decapods have been reported. Here we document the occurrence of two species of eubrachyuran crabs from the Pliocene Pinecrest Member of the Tamiami Formation, Sarasota County, based on complete and well preserved dorsal carapaces: the leucosiid Persephona cf. P. subovata (Rathbun, 1893), and the xanthid Paractaea cf. P. nodosa (Stimpson, 1860). The specimen of Paractaea cf. P. nodosa represents the second fossil record of the genus and the oldest occurrence known to date. The specimen of Persephona cf. P. subovata, despite its geographic occurrence, it is more similar anatomically to some extant tropical Eastern Pacific species than to any of the species occurring in Florida today. It is possible that ancestral populations of P. subovata were present in the tropical Eastern Pacific and western Atlantic before the water masses were isolated after the final closure of the currents connecting both water masses, and that the fossil Persephona here studied is part of a relict population of P. subovata that disappeared in the Atlantic after the late Pliocene.