Myocastorini is a tribe of
echimyid
Echimyidae is the family of neotropical spiny rats and their fossil relatives. This is the most species-rich family of Hystricognathi, hystricognath rodents. It is probably also the most ecologically diverse, with members ranging from fully ar ...
rodents, proposed in 2017, and containing the five extant genera ''
Callistomys
The painted tree-rat (''Callistomys pictus'') is a species of spiny rat from Brazil, restricted to north-eastern Bahia in eastern Brazil. It is the only species in the genus ''Callistomys''.
Identification
With a total length of ca. 30 cm ...
'', ''
Hoplomys
The armored rat (''Hoplomys gymnurus'') is a species of rodent in the family Echimyidae. It is monotypic within the genus ''Hoplomys''. It is found in Latin America, from northern Honduras to northwest Ecuador. It possesses a range of spines on ...
'', ''
Myocastor
''Myocastor'' is a genus of rodent that contains the living nutria (or coypu), as well as several fossil species.
Taxonomy
Due to similar cranial morphology, the nutria was once considered a close relative of the Caribbean hutias and placed toge ...
'', ''
Proechimys
''Proechimys'' is a genus of South American spiny rats of the family Echimyidae. All species of the genus are terrestrial. In the lowland Neotropical forests, ''Proechimys'' rodents are often the most abundant non-volant mammals. They are recogni ...
'', and ''
Thrichomys
''Thrichomys'' is a genus of South American rodents in the family Echimyidae. It contains at least five species, found in Bolivia, Brazil and Paraguay. They are as follows:
* Common punaré (''Thrichomys apereoides'')
* Foster's punaré (''Thri ...
''.
Definition
Myocastorini members share long upper incisor roots (except ''Callistomys''), and mid- to long-sized lower incisor roots. These five genera share either four (''Callistomys'', ''Thrichomys'') or five (''Hoplomys'', ''Myocastor'', ''Proechimys'') lophids on the lower deciduous fourth premolar, three roots anchoring the upper molars, and well-connected lophs on cheek teeth.
Members display a variety of lifestyles including terrestrial (''Hoplomys'', ''Proechimys'', ''Thrichomys''), arboreal (''Callistomys''), and amphibious (''Myocastor'') adaptations.
Phylogeny
On the one hand, the genus ''Proechimys'' is the sister group to the genus ''Hoplomys'' (armored rats), and both form a clade of lowland rainforest terrestrial spiny rats. On the other hand, ''Callistomys'' (painted tree-rats) is the sister group to ''Myocastor'' (coypus). In turn, these two pairs of genera share evolutionary affinities with ''Thrichomys'' (punaré).
References
Echimyidae
Mammal tribes
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