A study of arboreal echimyids in Brazilian and European collections revealed a number of morphological traits supporting the recognition of Loncheres grandis Wagner, 1845, currently included in Makalata Husson, 1978, as a full genus. Our proposition of a new genus for L. grandis changed the species content of Makalata, what led us to reformulate the generic diagnosis for this genus and other arboreal echimyids as well. The new genus can be distinguished by several external characters including its color pattern, striking differences in tail pilosity, and palmar and plantar pad morphology. Osteological distinguishing traits includes the shape of nasals, the structure of the postorbital process of the zygomatic arch, petrosal morphology, the presence of a posterior maxillary foramen, the crown pattern of molariform teeth, and baculum morphology.
