classified Oryzomys albiventer as a separate species from lowland mexicanus on the basis of clear morphometric differentiation and offered some comments on the status of crinitus, regillus, and aztecus, including the holotypes of the three forms in their morphometric analyses. The holotypes of regillus and aztecus were at the upper end of the range of variation in their large series of mexicanus from the western lowlands, and crinitus clustered with specimens of O. peninsulae from the tip of the Baja California Peninsula. They suggested that regillus and aztecus may represent no more than robust upland populations of mexicanus, but could not exclude the possibility that they represent a different species. That crinitus, which occurs at over altitude in the Valley of Mexico, was the same species as peninsulae from the lowlands of the Baja California Peninsula they could not accept and they recommended further research to determine the relationships of crinitus. A specimen from inland Michoacán has Cytb data characteristic of mexicanus, but Hanson and colleagues did not have data for other interior Mexican Oryzomys. The holotype of the species Oryzomys fulgens, which Thomas had described in 1893, has no more precise locality than "Mexico", but the Valley of Mexico has been suggested as its origin. It is a large, coarse-furred, bright reddish, long-tailed species with a broad skull with widely spreading zygomatic arches. Goldman wrote that it was similar to crinitus, but more intensely colored, and differed in the form of the interorbital region; he retained it as a separate species pending further investigations. Carleton and Arroyo-Cabrales noted that archival research may yet uncover the precise origin of O. fulgens, which could establish it as an older name for one of the other central Mexican Oryzomys. Texas to Nicaragua Oryzomys populations from Texas to Nicaragua form a single Cytb clade, within which the average sequence divergence is 1.28%, and Hanson and colleagues proposed that the name Oryzomys couesi be restricted to this clade. These populations correspond to two subspecies recognized by Goldman (O. c. aquaticus and O. c. couesi) and an island form he retained as a species (O. cozumelae). Two other subspecies Goldman recognized, O. c. richmondi and O. c. peragrus, and a third, O. c. pinicola, that was described after Goldman's paper occur in the same region, but have not been studied genetically. The northernmost populations of Oryzomys couesi, those in southernmost Texas and nearby Tamaulipas, Mexico,