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 Holochilus sciureus Wagner 1842 Holochilus sciureus Wagner 1842 , Arch. Naturgesch., ser. 8, 1: 16 . Type Locality: Brazil , Minas Gerais State , Rio São Francisco. Vernacular Names: Amazonian Marsh Rat . Synonyms: Holochilus amazonicus Osgood 1915 ; Holochilus berbericensis Morrison-Scott 1937 ; Holochilus guianae Thomas 1901 ; Holochilus incarum Thomas 1920 ; Holochilus multannus Ameghino 1889 ; Holochilus nanus Thomas 1897 ; Holochilus venezuelae J. A. Allen 1904 . Distribution: Broad reaches of Orinoco and Amazon River basins: Venezuela (including an isolated locality in the Maracaibo Basin, NW of the Andes; see Linares, 1998 :Fig. 169), Guianas, N and C Brazil , and Amazonian regions of Colombia , Ecuador , Perú , and Bolivia . Conservation: IUCN – Lower Risk (lc). Discussion: Discrimination from H. brasiliensis documented by Massoia (1980 a , 1981 ), who raised sciureus to specific rank. Many forms swept under Hershkovitz’s (1955 a ) concept of brasiliensis actually belong to this "species," which itself is a composite—e.g., Amazonian populations characterized by a 2n = 55-56 ( Patton et al., 2000 ), but Venezuelan populations characterized by 2n = 44 ( Aguilera and Perez-Zapata, 1989 ). The latter authors, and Aguilera et al. (1993) , have recognized H. venezuelae as a species, but Linares (1998) continued to employ H. sciureus for those same series, acknowledging venezuelae as a subspecies. In addition to venezuelae , Reig (1986) listed amazonicus and guianae as probable valid species. The persisting disagreement over number of valid species, uncertain correspondence of karyotypic variants to definable morphologies, and vagueness of distributional limits will only be illuminated by wholesale generic revision. Synonymy of multannus asserted by Massoia and Pardiñas (1993).