Sloth Species Research Articles

Viruses isolated from Panamanian sloths.

Seven virus strains were isolated in Vero cells from whole blood samples from 80 wild-caught sloths, Bradypus variegatus and Choloepus hoffmanni, from Central Panamá. Four strains of at least two different serotypes are related to Changuinola virus; two of these were associated with prolonged or recrudescent viremias. One strain is an antigenic subtype of Punta Toro virus, and another, described here as Bradypus-4 virus, is a new, antigenically ungrouped virus. A second new virus from sloths, Utive virus, forms an antigenic complex within the Simbu serogroup with Utinga and Pintupo viruses. Tests on sequential plasma samples from radio-marked free-ranging sloths and from recently captured animals maintained in captivity showed that both species develop neutralizing antibodies following naturally acquired virus infections. Antibodies against the Changuinola and Simbu serogroup viruses are widespread in both sloth species and are especially prevalent in Choloepus, but are virtually absent in all other wild vertebrate species tested.

Experimental St. Louis encephalitis virus infection of sloths and cormorants.

Experimental infection of 11 Bradypus variegatus and Choloepus hoffmanni sloths with St. Louis encephalitis (SLE) virus produced detectable viremias of seven to 27 (median 13) days duration and maximum titers of 2.7 to 6.5 (median 5.1) log10 median suckling mouse intracranial lethal doses (SMicLD50) per ml. Experimental SLE viremia onset was delayed and maximum titer depressed in two sloths concurrently infected with naturally acquired viruses. SLE viremias in four experimentally inoculated cormorants Phalacrocorax olivaceus were shorter, and of equal or lower titer, than in sloths. Colonized Culex pipiens quinquefasciatus mosquitoes were infected by feeding on sloths circulating at least 4.8 log10 SMicLD50 of SLE virus per ml, and subsequently transmitted the infection to mice and chicks. An uninoculated baby Bradypus became infected by contact transmission from its mother. The antibody response of sloths to SLE virus was slow, being undetectable until several weeks post-inoculation. However, both sloth species developed high and long-lasting neutralizing and hemagglutination-inhibition antibody titers. The complement-fixation antibody response in Bradypus was lower and slower to develop than in Choloepus. Sloths with naturally acquired SLE virus antibody did not become detectably viremic after experimental inoculation. Neither sloths nor cormorants become overly ill from SLE virus infection.

Megalonyx hogani, a new species of ground sloth from Gould, Oklahoma

Megalonyx hogani, a new species of ground sloth from Gould, Oklahoma

On a new species of three-toed Sloth from Costa Rica

On a new species of three-toed Sloth from Costa Rica

I. On the scelidothere ( scelidotherium, leptocephalum , Owen), a large extinct terrestrial sloth

The extinct species of large terrestrial Sloth, indicated by the above name, was first made known by portions of its fossil skeleton having been discovered by Charles Darwin, Esq., F. R. S., at Punta Alta, Northern Patagonia. These portions were described by the author in the Appendix to the 'Natural History of the Voyage of H. M. S. Beagle'. The subsequent acquisition by the British Museum of the collection of Fossil Mammalia brought from Buenos Ayres by M. Bravard, has given further evidence of the generic distinction of the Scelidothere, and has supplied important characters of the osseous system, and especially of the skull, which the fragments from the hard consolidated gravel of Punta Alta did not afford.

VII. On the Scelidothere (Scelidotherium leptocephalum, Owen)

The extinct species of large terrestrial Sloth, indicated by the above name, was first made known by portions of its fossil skeleton discovered by Charles Darwin, Esq., F. R. S., at Punta Alta, Northern Patagonia, which were described by me in the chapters of the Appendix to the ‘Natural History of the Voyage of H. M. S. Beagle,’ treating of the “Fossil Mammalia” collected during that voyage. The subsequent acquisition by the British Museum of the collection of Fossil Mammalia brought from the pleistocene beds, Buenos Ayres, by M. Bravard, has given further evidence of the generic distinction of the Scelidothere from the other Gravigrades of the Bruta phylophaga , and has supplied important characters of the osseous system, and especially of the skull, which the fragments from the hard consolidated gravel of Punta Alta did not afford. The best portion of the cranium from the latter locality wanted the facial part anterior to the orbit, and the greater part of the upper walls; sufficient, however, remained to indicate the peculiar character of its slender proportions, and hence the name leptocephalum proposed for the species.