Anomalous colourations occur in many tropical vertebrates. However, they are considered rare in wild populations, with very few records for the majority of animal taxa. We report two new cases of anomalous colouration in mammals. Additionally, we compiled all published cases about anomalous pigmentation registered in Neotropical mammals, throughout a comprehensive review of peer reviewed articles between 1950 and 2010. Every record was classified as albinism, leucism, piebaldism or eventually as undetermined pigmentation. As results, we report the new record of a leucistic specimen of opossum (Didelphis sp.) in southern Brazil, as well as a specimen of South American fur seal (Arctocephalus australis) with piebaldism in Uruguay. We also found 31 scientific articles resulting in 23 records of albinism, 12 of leucism, 71 of piebaldism and 92 records classified as undetermined pigmentation. Anomalous colouration is apparently rare in small terrestrial mammals, but it is much more common in cetaceans and michrochiropterans. Out of these 198 records, 149 occurred in cetaceans and 30 in bats. The results related to cetaceans suggest that males and females with anomolous pigmentation are reproductively successful and as a consequence their frequencies are becoming higher in natural populations. In bats, this result can be related to the fact these animals orient themselves primarily through echolocation, and their refuges provide protection against light and predation. It is possible that anomalous colouration occurs more frequently in other Neotropical mammal orders, which were not formally reported. Therefore, we encourage researchers to publish these events in order to better understand this phenomenon that has a significant influence on animal survival.Keywords: albinism, hypopigmentation, leucism, Neotropical mammals, piebaldism.Coloração anômala em mamíferos Neotropicais: uma revisão com novos registros para Didelphis sp. (Didelphidae, Didelphimorphia) e Arctocephalus australis (Otariidae, Carnivora)
ResumoColorações anômalas ocorrem em muitos vertebrados tropicais. Entretanto, estas são consideradas raras em populações selvagens, havendo poucos registros para a maioria dos táxons. Reportam-se, neste estudo, dois novos casos de coloração anômala em mamíferos. Além disso, por meio de uma extensa revisão bibliográfica, foram compilados os casos publicados sobre coloração anômala em mamíferos neotropicais entre 1950 e 2010. Cada registro foi classificado como albinismo, leucismo, piebaldismo ou, eventualmente, como coloração indeterminada. Como resultados, reportouse o registro de um espécime leucístico de gambá (Didelphis sp.) no sul do Brasil e de um espécime de lobo-marinho sul-americano (Arctocephalus australis) com piebaldismo no norte do Uruguai. Também foram analisados 31 artigos científicos, resultando em 23 registros de albinismo, 12 de leucismo, 71 de piebaldismo e 92 registros classificados como de pigmentação indeterminada. A coloração anômala aparentemente é rara em pequenos mamíferos terrestres...
