Mesomys
Mesomys is a genus of South American spiny rats in the family Echimyidae.
The genus name Mesomys derives from the two ancient 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 of Echimys.
Phylogeny
Mesomys is a member of the Echimyini clade of arboreal Echimyidae rodents. The closest relative of Mesomys is Lonchothrix, reflecting the fact that these taxa have once been classified in the Eumysopinae, a subfamily now recognized as an artificial assemblage. These two genera share phylogenetic affinities with several taxa and clades: Echimys, Phyllomys, Makalata, Pattonomys, and Toromys ; the bamboo rats Dactylomys, Olallamys, Kannabateomys together with Diplomys and Santamartamys ; and Isothrix.