Fossa (animal) - Taxonomy

Taxonomy

The fossa was formally described by Edward Turner Bennett on the basis of a specimen from Madagascar sent by Charles Telfair in 1833. The common name is the same as the generic name of the Malagasy civet (Fossa fossana), but they are different species. Because of shared physical traits with civets, mongooses, and cats (Felidae), its classification has been controversial. Bennett originally placed the fossa as a type of civet in the family Viverridae, a classification that long remained popular among taxonomists. Its compact braincase, large eye sockets, retractable claws, and specialized carnivorous dentition have also led some taxonomists to associate it with the felids. In 1939, William King Gregory and Milo Hellman placed the fossa in its own subfamily within Felidae, the Cryptoproctinae. George Gaylord Simpson placed it back in Viverridae in 1945, still within its own subfamily, yet conceded it had many cat-like characteristics.

In 1993, Géraldine Veron and François Catzeflis published a DNA hybridization study suggesting that the fossa was more closely related to mongooses (family Herpestidae) than to cats or civets. However, in 1995, Veron's morphological study once again grouped it with Felidae. In 2003, molecular phylogenetic studies using nuclear and mitochondrial genes by Anne Yoder and colleagues showed that all native Malagasy carnivorans share a common ancestry that excludes other carnivores (meaning they form a clade, making them monophyletic) and are most closely related to Asian and African Herpestidae. To reflect these relationships, all Malagasy carnivorans are now placed in a single family, Eupleridae. Within Eupleridae, the fossa is placed in the subfamily Euplerinae with the falanouc (Eupleres goudoti) and Malagasy Civet, but its exact relationships are poorly resolved.

An extinct relative of the fossa was described in 1902 from subfossil remains and recognized as a separate species, Cryptoprocta spelea, in 1935. This species was larger than the living fossa (with a body mass estimate roughly twice as great), but otherwise similar. Across Madagascar, people distinguish two kinds of fossa—a large fosa mainty ("black fossa") and the smaller fosa mena ("reddish fossa")—and a white form has been reported in the southwest. It is unclear whether this is purely folklore or individual variation—related to sex, age or instances of melanism and leucism—or whether there is indeed more than one species of living fossa.