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''Voalavo'' is a genus of rodent in the subfamily Nesomyinae, found only in Madagascar. Two species are known, both of which occur in mountain forest above 1250 m (4100 ft) altitude; ''Voalavo gymnocaudus'' lives in northern Madagascar and ''Voalavo antsahabensis'' is restricted to a small area in the central part of the island. The genus was discovered in 1994 and formally described in 1998. Within Nesomyinae, it is most closely related to the genus ''Eliurus'', and DNA sequence data suggest that the current definitions of these two genera need to be changed. Species of ''Voalavo'' are small, gray, mouse-like rodents, among the smallest nesomyines. They lack the distinctive tuft of long hairs on the tail that is characteristic of ''Eliurus''. The tail is long and females have six mammae. In ''Voalavo'', there are two glands on the chest (absent in ''Eliurus'') that produce a sweet-smelling musk in breeding males. In the skull, the facial skeleton is long and the braincase is smooth. The incisive foramina (openings in the front part of the palate) are long and the bony palate itself is smooth. The molars are somewhat hypsodont (high-crowned), though less so than in ''Eliurus'', and the third molars are reduced in size and complexity. ==Taxonomy== A specimen of the genus was first collected in 1994 in Anjanaharibe-Sud, northern Madagascar. The genus was named ''Voalavo'' in 1998 by Michael Carleton and Steven Goodman, with a single species, the type ''Voalavo gymnocaudus'', restricted to the Northern Highlands of Madagascar. The generic name ''Voalavo'' is a Malagasy word for "rodent". A second species, ''Voalavo antsahabensis'', was named by Goodman and colleagues in 2005 from the region of Anjozorobe in the Central Highlands. The two ''Voalavo'' species are closely related and quite similar, but differ in various subtle morphological characters (mainly measurements) and by 10% in the sequence of the mitochondrial gene cytochrome ''b''. ''Voalavo'' is part of the subfamily Nesomyinae, which includes nine genera that are all restricted to Madagascar. Before the discoveries of ''Monticolomys'' (published in 1996) and ''Voalavo'' (1998), all of the known genera within Nesomyinae were quite distinct from each other, so much so that phylogenetic relationships among them long remained obscure. Like ''Monticolomys'' (closely related to ''Macrotarsomys''), however, ''Voalavo'' shows clear similarities to another nesomyine genus, ''Eliurus''. In their description of ''Voalavo'', Carleton and Goodman argued that, although closely related, ''Eliurus'' and ''Voalavo'' form separate monophyletic groups; but a 1999 molecular phylogenetic study by Sharon Jansa and colleagues, who compared cytochrome ''b'' sequences among nesomyines and other rodents, found that ''Voalavo gymnocaudus'' was more closely related to ''Eliurus grandidieri'' than to other species of ''Eliurus''. This finding called into question the separate generic status of ''Voalavo''. However, tissue samples of ''Eliurus petteri'', a species that is thought to be closely related to ''E. grandidieri'', were not available, so this species could not be included in the study. Data from nuclear genes also supports the relationship between ''V. gymnocaudus'' and ''E. grandidieri'', but ''E. petteri'' remains genetically unstudied and the taxonomic issue has not been resolved. Molecular phylogenetic analysis of nuclear DNA supports a close relationship between ''Eliurus'', ''Voalavo'', and two other nesomyine genera, ''Gymnuromys'' and ''Brachytarsomys''. These genera are more distantly related to the other nesomyine genera and even more distantly to the other subfamilies of the family Nesomyidae, which occur in mainland Africa. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Voalavo」の詳細全文を読む スポンサード リンク
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