A Fossil Flea in Dominican Amber: Description of a New Genus and Species (Siphonaptera: Rhopalopsyllidae) with Notes on Convergent Evolution in Bird Fleas and the Historical Biogeography of Pertinent Mammals

A fossil flea in Dominican amber, Pulicophoenix succinus, new genus, new species (Siphonaptera: Rhopalopsyllidae, Rhopalopsyllinae) is described and figured. The fossil is 25–40 million years in age, with a putative date of lower Oligocene-upper Eocene, and exhibits some of the characteristic features seen in 24 genera or subgenera of bird fleas in five families. These diagnostic traits are discussed and illustrated for various examples of avian fleas, and it is concluded that Pulicophoenix was undoubtedly a bird flea and probably was a ‘perambulatory’ type that must actively seek out a host. Comparisons with mammalian-infesting fleas suggest that these specialized characters of bird fleas are somehow adaptive in nature and reflect the physiognomy and habits of the host. The family and subfamily levels in Siphonaptera evolved during the Cretaceous in some instances to the Miocene for others. Evolution has also proceeded slowly at the generic level for many fleas, over a period of millions of years. In the Mesozoic Era, Africa and South America did not share a siphonapteran fauna of pulicid or any other extant group of fleas. The modern African faunae of mammals and fleas have Eurasian roots, even though some of their components originated in Africa. The forebears of the pulicid and ctenophthalmine fleas of South America, and those of their rodent hosts, originated in Africa and are thought to have rafted to South America in the Eocene. The only other true fossil fleas that have been named and described are four species of Paleopsylla Wagner, 1903 (an extant genus) in Baltic amber, and three pulicids in Dominican amber. It is possible that Pulicophoenix is still alive today, since very little is known about bird fleas of South America and the Greater Antilles, and since many other insect fossils in Dominican amber represent extant genera.