Summary: A new species of three-toed sloth (Mammalia: Xenarthra) from
PanamB, with a review of the genus Bradypus
Robert P. Anderson and Charles 0. Handley, Jr.
(RPA) Natural History Museum & Biodiversity Research Center, and Department of Ecology &
Evolutionary Biology, 1345 Jayhawk Blvd., University of Kansas,
Lawrence, Kansas 66045-7561, U.S.A.;
(COH, Jr.--deceased) Division of Mammals, National Museum of Natural History,
Smithsonian Institution, Washington, D.C. 20560, U.S.A.
Abstract.-Morphological and morphometric analyses of three-toed sloths
(Bradypus) from the islands of Bocas del Toro reveal rapid differentiation of
several populations during the Holocene. These islands, lying off the Caribbean
coast of western Panamii, were separated from the adjacent mainland by rising
sea levels during the past 10,000 years. The sequence of island formation and
the approximate ages of the islands are known. In at least four independent
events, sloths on five of the islands evolved smaller size following insulari-
zation. Sloths on the younger islands remain conspecific with mainland pop-
ulations of Bradypus variegatus. On Isla Escudo de Veraguas-the oldest and
most remote island of the archipelagohowever, the three-toed sloth has dif-
ferentiated to the species level, and we here describe it as Bradypuspygmaeus.
We provide updated diagnoses and distributions for the species of Bradypus,