Diplomys is a member of the Echimyini clade of arboreal Echimyidae rodents. The closest relative of Diplomys is Santamartamys, reflecting the fact that these taxa have once been classified in the same genus.[3] These two genera constitute the sister group of the "Dactylomyines", a clade of South American bamboo rats.[4] All these taxa are closely related to the genera Echimys, Phyllomys, Makalata, Pattonomys, and Toromys. In turn, these genera share phylogenetic affinities with the clade containing Lonchothrix and Mesomys, and with Isothrix.[5]
^Lara, Márcia C.; Patton, James L.; da Silva, Maria Nazareth F. (1996). "The Simultaneous Diversification of South American Echimyid Rodents (Hystricognathi) Based on Complete Cytochrome b Sequences". Molecular Phylogenetics and Evolution. 5 (2): 403–413. Bibcode:1996MolPE...5..403L. doi:10.1006/mpev.1996.0035. PMID8728398.
^Galewski, Thomas; Mauffrey, Jean-François; Leite, Yuri L. R.; Patton, James L.; Douzery, Emmanuel J. P. (2005). "Ecomorphological diversification among South American spiny rats (Rodentia; Echimyidae): a phylogenetic and chronological approach". Molecular Phylogenetics and Evolution. 34 (3): 601–615. Bibcode:2005MolPE..34..601G. doi:10.1016/j.ympev.2004.11.015. PMID15683932.
^Upham, Nathan S.; Patterson, Bruce D. (2012). "Diversification and biogeography of the Neotropical caviomorph lineage Octodontoidea (Rodentia: Hystricognathi)". Molecular Phylogenetics and Evolution. 63 (2): 417–429. Bibcode:2012MolPE..63..417U. doi:10.1016/j.ympev.2012.01.020. PMID22327013.
^Fabre, Pierre-Henri; Galewski, Thomas; Tilak, Marie-ka; Douzery, Emmanuel J. P. (2013-03-01). "Diversification of South American spiny rats (Echimyidae): a multigene phylogenetic approach". Zoologica Scripta. 42 (2): 117–134. doi:10.1111/j.1463-6409.2012.00572.x. ISSN1463-6409. S2CID83639441.
^Upham, Nathan S.; Patterson, Bruce D. (2015). "Evolution of Caviomorph rodents: a complete phylogeny and timetree for living genera". In Vassallo, Aldo Ivan; Antenucci, Daniel (eds.). Biology of caviomorph rodents: diversity and evolution. Buenos Aires: SAREM Series A, Mammalogical Research — Sociedad Argentina para el Estudio de los Mamíferos. pp. 63–120.