The Atlantic Forest climbing mouse (Rhipidomys mastacalis) is an arboreal rodent species in the family Cricetidae from South America. It is found in the Atlantic Forest of southeastern Brazil at elevations from sea level to 1500 m. Its karyotype is 2n = 44, FN = 74-80. It is sometimes also referred to as the long-tailed climbing mouse. Rhipidomys macrurus is similarly sometimes commonly known as the "long-tailed rhipidomys", while rodents of genus Vandeleuria are also commonly known as long-tailed climbing mice.