''Mesomys'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

South American South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

spiny rats in the family

Echimyidae Echimyidae is the family of neotropical spiny rats and their fossil relatives. This is the most species-rich family of hystricognath rodents. It is probably also the most ecologically diverse, with members ranging from fully arboreal to terr ...

. The genus name ''Mesomys'' derives from the two

ancient greek Ancient Greek (, ; ) includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Greek ...

words (), meaning "middle of, between", and (), meaning "mouse, rat". It refers to the fact that these rodents — literally the "middle mouse" — were considered an intermediate form between the genus ''Loncheres'' and the genus ''Echinomys'', both of which are now known to be

synonyms A synonym is a word, morpheme, or phrase that means precisely or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are a ...

of ''

Echimys ''Echimys'' is a genus of the spiny rats family, the Echimyidae. Members of this genus are collectively called spiny tree-rats. The genus name ''Echimys'', and also its synonym ''Echinomys'', derive from the two Ancient Greek words (), meanin ...

''.

Extant species

Phylogeny

''Mesomys'' is a member of the

Echimyini Echimyini is a tribe of echimyid rodents, proposed in 2016, and containing 13 extant genera: all of the tree rats '' Echimys'', ''Phyllomys'', '' Makalata'', '' Pattonomys'', '' Toromys'', '' Diplomys'', '' Santamartamys'', and '' Isothrix'', the ...

clade of

arboreal Arboreal locomotion is the locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some animals may scale trees only occasionally (scansorial), but others are exclusively arboreal. The hab ...

Echimyidae rodents. The closest relative of ''Mesomys'' is ''Lonchothrix'', reflecting the fact that these taxa have once been classified in the

Eumysopinae Echimyidae is the family of neotropical spiny rats and their fossil relatives. This is the most species-rich family of hystricognath rodents. It is probably also the most ecologically diverse, with members ranging from fully arboreal to terre ...

, a subfamily now recognized as an artificial assemblage. These two genera share phylogenetic affinities with several taxa and clades: (i) ''Echimys'', ''Phyllomys'', ''Makalata'', ''Pattonomys'', and ''Toromys'' ; (ii) the bamboo rats ''Dactylomys'', ''Olallamys'', ''Kannabateomys'' together with ''Diplomys'' and ''Santamartamys'' ; and (iii) ''Isothrix''.

References

{{Taxonbar, from=Q911378 Echimyini Rodent genera Taxa named by Johann Andreas Wagner