490.

White-bellied Marsh Rice Rat

Oryzomys albiventer

French: Oryzomys a ventre blanc / German: WeilRbauch-Sumpfreisratte / Spanish: Rata arrocera de marisma de vientre blanco

Other common names: White Venter Rice Rat

Taxonomy. Oryzomys albiventer Merriam, 1901, Ameca, 1220 m, Jalisco, Mexico.

Oryzomys albiventer originally was described as a full species but subsequently considered a subspecies of O. couesi or O. palustris. Earlier name fulgens by O. Thomas in 1893, is of uncertain provenance but supposedly from the Valley of Mexico. It may apply to O. albiventer or to other upland rice rats from interior Mexico, but archival work is required to determine exact provenance offulgens. Monotypic.

Distribution. Apparently endemic to the Mesa de Anahuac in C & E Jalisco, S Guanajuato, and N Michoacan, Mexico.

Descriptive notes. Head-body 116-142 mm, tail 129-173 mm, hindfoot 33-40 mm. No specific data are available for body weight. The White-bellied Marsh Rice Rat is characterized by large size, relatively and absolutely long tail, heavily constructed skull (occipito-nasal length ¢.31-34 mm), and robust molars (crown length of upper molar series ¢.4-5 mm). Compared with other species of Oryzomys, the White-bellied Marsh Rice Ratis brightly colored. Type description of “underparts white,” the basis for the specific epithet and common name, is misleading because basal portion of ventral hairs is pale gray and only distal portion is pure white; these white tips do not obscure basal gray and thus create underparts that appear pale gray to grayish white. Skull is large, with robust cheekteeth, broad zygomatic arches, long incisive foramina, and long nasal bones that extend distally beyond premaxillae. Karyotype is unknown.

Habitat. Deciduous tropical woodlands at elevations of 1200-1800 m.

Food and Feeding. No information.

Breeding. No information.

Activity patterns. No information.

Movements, Home range and Social organization. No information.

Status and Conservation. Not assessed on The [UCN Red List. The White-bellied Marsh Rice Rat may be in risk of extinction because of its small distribution in the heavily populated region in central Mexico where habitat conversion to cropland has been extreme. Renewed survey work is required to assess distribution and local population status.

Bibliography. Arroyo-Cabrales (2014a), Carleton & Arroyo-Cabrales (2009), Elliot (1903a), Merriam (1901a), Thomas (1893b).