Ghost rodents: Albinism in Australian rodent species

While almost half of all mammal species are rodents, records of albinism in free-ranging rodents are very rare. Australia has a large and diverse assemblage of native rodent species, but there are no records of free-ranging albino rodents in the published literature. In this study, we aim to improve our understanding of the occurrence of albinism in Australian rodent species by collating contemporary and historic records of this condition and providing an estimate of its frequency. We found 23 records of albinism (i.e., a complete loss of pigmentation), representing eight species, in free-ranging rodents native to Australia, with the frequency of albinism being generally <0.1%. Our findings bring the total number of rodent species in which albinism has been recorded globally to 76. While native Australian species represent only 7.8% of the world's murid rodent diversity, they now account for 42.1% of murid rodent species known to exhibit albinism. We also identified multiple concurrent albino records from a small island population of rakali (Hydromys chrysogaster) and discuss the factors that may contribute to the relatively high frequency (2%) of the condition on this island. We suggest that the small number of native albino rodents recorded in mainland Australia over the last 100 years means that traits associated with the condition are likely deleterious within populations and are thus selected against.

First photographic record of albinism in Baiomys taylori (Rodentia: Cricetidae)

Cases of albinism have been reported in less than 2% of living rodent species. Here, we report the first description of complete albinism in Baiomys taylori along with photographic evidence. This adult female was captured on three occasions as part of a long-term small mammal study on rangelands of extreme southern Texas. The individual was developing teats upon the third capture, an early sign of pregnancy. Despite selective pressures against albino phenotypes, this animal was able to survive to adulthood and potentially pass its albino alleles to offspring.

First Italian record for a partial Isabelline colouration in a European mole, Talpa europaea

The European mole Talpa europaea Linnaeus, 1758 is a quite common species in Central Italy. I report the first Isabelline individual of this species recorded in the scientific literature. Actually, this species is quite widespread throughout Europe, but coat-colouration anomalies have never been described in Italian mole populations. Further research is therefore needed to determine the percentage of occurrence of anomalous individuals and the evolutionary history of coat anomalies in moles.

First record of albinism in spiny rats of genus Proechimys (Rodentia: Echimyidae) from Western Amazon

Albinism is a rare condition in natural populations. One of the factors that would lead to higher allele frequency for the albino phenotype is bottleneck events, causing small population sizes and loss of genetic diversity. Here, we report the first record of albinism in one specimen of Proechimys gardneri from Porto Velho, Rondônia, Brazil. This is also the first record of albinism for the genus and for the family Echimyidae. We identified the specimen through morphology and confirmed the identification by 801 base pairs (bp) of mitochondrial marker cytochrome b (Cyt b). We also discuss the selection against albino phenotype in natural populations.

The first report of albinism in a Sundaland endemic rodent

Albinism, a congenital disorder that results in a lack of melanin deposition, is common in domesticated animals but rare in nature. Among the ∼2500 species of rodents worldwide, only 67 have published reports of albinism. Here we report the capture of an albino murid (Muridae: Rodentia) from Mt. Singgalang in West Sumatra, Indonesia. The specimen is an adolescent but sexually mature male Maxomys hylomyoides, a montane Sumatran endemic. To our knowledge, this specimen represents the first reported albino rodent from Indonesia and Sundaland, and only the second from Southeast Asia.

Albinism in Didelphis virginiana (Kerr, 1792): the first reported case in Mexico

Atypical colorations occur in different groups of vertebrates. The loss of melanin in the skin, hair and eyes is the result of an autosomal recessive genetic entity. It causes individuals to present with a white coloration of the skin and hair, as well as red eyes, known as albino. This manuscript documents the first record in Mexico of complete albinism in a marsupial, Didelphis virginiana, captured in the Yucatan peninsula.