Date of this Version
The species Oryzomys dimidiatus was originally named and described by Thomas (Ann. Mag. Nat. Hist., ser. 7, 15:584-591, 1905) as a member of the genus Nectomys on the basis of a single specimen from the Rio Escondido, 7 miles below Rama, Nicaragua ( approximately 1 km. S and 8½ km. E Ranla, 20 m, Zelaya), obtained by W. G. Palmer on 5 November 1904. Although there has been speculation on the relationships of this taxon (currently regarded as the only member of the subgenus Micronectmays, genus Oryzomys-see Hershkovitz, J. Mamm., 51:789-794, 1970, for review), the holotype has remained the only known specimen.
A second individual (University of Kansas hluseum of Natural History no. 106607) assign-able to this species was taken on 26 July 1966 by R. W. Turner at El Recreo, 25 m, Zelaya, Nicaragua, approximately 15 kilometers to the west of the type locality. This rat, a young adult male, was trapped in a stand of cane, 8 to 10 feet tall, along the south bank of the Rio Mico. The cane was nearly impenetrable excepting for two paths through it to the river, and it was along these paths that traps were set, baited with rolled oats. In addition to O . dimidiatus, other small mammals taken at this place included Oryzomys caliginosus, O. fulvescens, O. palustris, Sigmodon hispidus, and one Sylvilagus brasiliensis that was shot along the edge of the cane.