Paleobiogeography of the fossil box crab Calappilia (Brachyura: Calappidae) with a new species from the Eocene-Oligocene of Florida, USA

Abstract

Members of the family Calappidae, or box crabs, date back to at least the Eocene, with Calappilia being the most species-rich calappid genus in the fossil record. The European species of Calappilia were reviewed recently, but less work has been done lately on the American species. We describe Calappilia calculosa n. sp. based on carapaces originating from the uppermost Eocene to lowermost Oligocene Rotularia vernoni Zone (Priabonian-Rupelian) in Suwannee County, Florida, USA. The new species is the youngest member of the genus in North America thus far. We further discuss some other occurrences of Calappilia that includes reassigning Calappilia ocalanus (Ross, Lewis and Scolaro, 1964) to Calappa, in part to better interpret the paleobiogeography of Calappilia. A worldwide paleobiogeographic analysis of Calappilia suggests that the genus first appeared in North America or Europe in the early Cenozoic. Rapid dispersal and radiation seem to have occurred in the Eocene because Calappilia is also reported from Eocene sediments of the Pacific side of Mexico and Indonesia. We hypothesize that individuals of Calappilia crossed the Central American Seaway prior to the closure of the Isthmus of Panama and they also migrated across the Tethys Sea. Miocene occurrences are known from Brazil, Chile, Australia, and New Zealand, suggesting dispersal well into the Southern Hemisphere by the Miocene. Quaternary occurrences have not been confirmed thus far.