Pelage Variation and an Update on the Geographic Distribution of the Black-tailed Marmoset Mico melanurus.

The black-tailed marmoset, Mico melanurus, occurs in Brazil, Bolivia, and Paraguay. There are some gaps in our understanding of its distribution in the Brazilian states of Mato Grosso and Rondônia. Based on field surveys and a literature review, we present new records and an updated distribution map for the species. We also assess geographic and individual variation in the pelage of M. melanurus. For the surveys, we used the linear-transect method, adapted to include the use of playback. We also examined 11 specimens from museum collections--four from the mammal collection of the Cáceres campus of the Mato Grosso State University, and seven from the Goeldi Museum, Belém, Pará. Specimens from Vilhena and Chupinguaia had the darkest pelage, representing a previously unrecorded phenotype for the species, while specimens from the Guaporé, São Miguel, and Cautário river basins were of the palest phenotype. The thigh stripe, otherwise prominent, is inconspicuous or absent in some specimens. The new records extend the geographic distribution of M. melanurus to the northwest, suggesting contact zones with Mico nigriceps and Mico intermedius. [ABSTRACT FROM AUTHOR]