The closest relatives of the genus Thrichomys are two
clades consisting of pairs of
Myocastorini genera: Callistomys (the painted tree-rat) and Myocastor (the coypu or nutria) in one clade, and Hoplomys (the armored rat) and Proechimys in the other.
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PMID22327013.
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S2CID83639441.