Order Rodentia - Family Cricetidae Author Wilson, Don E. Author Reeder, DeeAnn text 2005 The Johns Hopkins University Press Baltimore Mammal Species of the World: a Taxonomic and Geographic Reference (3 rd Edition), Volume 2 955 1189 book chapter 0-8018-8221-4 10.5281/zenodo.7316535 Rhipidomys mastacalis (Lund 1840) [Rhipidomys] mastacalis (Lund 1840) , K. Dansk. Vid. Selsk. Naturv. Math. Afhandl.: 24 . Type Locality: Brazil , Minas Gerais State , Rio das Velhas, Lagoa Santa. Vernacular Names: Atlantic Forest Rhipidomys . Synonyms: Rhipidomys leucodactylus (Wagner 1845) ; Rhipidomys maculipes (Pictet and Pictet 1844) . Distribution: Atlantic Forest region, SE Brazil ( Pernambuco to São Paulo ). Conservation: IUCN – Lower Risk (lc). Discussion: R. leucodactylus section sensu Tribe (1996) . Comprehending the definition and distribution of Lund’s mastacalis stands at the center of systematic problems involving medium-sized rhipidomys with whitish venters. As broadly conceived by Cabrera (1961), the form contained, as subspecies or complete synonyms, the following taxa now associated with other species: R. emiliae , R. macrurus , R. nitela (including fervidus and yuruanus ), tenuicauda (= R. fulviventer ), and R. venezuelae (see individual accounts). The restricted concept of the species, as currently understood, circumscribes yet another form endemic to the Atlantic Forest zone, SE Brazil . Although the morphological distinction between R. macrurus and R. mastacalis is not well marked ( Tribe, 1996 ), chromosomal studies consistently reveal populations with low (48-52) versus high (74-80) fundamental numbers, respectively (2n = 44 in all; Andrades-Miranda et al., 2002 a ; Svartman and Almeida, 1993 ; Zanchin et al., 1992 a ). The distributions of the two in SE Brazil appear to intertwine in complex fashion; other species are likely involved as noted by Tribe (1996) , who cited many specimens as cf . macrurus or as species indeterminate.