756.

Yucatan Vesper Rat

Otonyctomys hatti

French: Nyctomys du Yucatan / German: Yucatan-Kletterratte / Spanish: Rata laucha de Yucatan

Other common names: Hatt's Vesper Mouse, Hatt's Vesper Rat, Yucatan Vesper Mouse

Taxonomy. Olonyctomys hatti Anthony, 1932, Chichén Itza, Yucatan, Mexico.

This species is monotypic.

Distribution. Endemic to the Yucatan Peninsula, only reported from ten locations in Mexico, NE Guatemala, and N Belize.

Descriptive notes. Head-body 90-116 mm, tail 60-127 mm; weight 24-94 g. The Yucatan Vesper Rat has short face, and black hair around eyes to form masks . Ears are medium-sized and naked, with hair at bases. Dorsum is uniformly tawny orange and bright; venter is white. Tail is as long as body, thick, hairy, and bright, with tuft of hairs at tip. Hinglegs are modified for arboreal life. Large auditory bullae occupying most ofskull base are distinctive. There are two pairs of inguinal teats. Karyotype is 2n = 50, with seven pairs of large to small metacentric and submetacentric chromosomes and graded series of 17 pairs of large to small acrocentric elements. X-chromosome is metacentric, and Y-chromosome is long and submetacentric.

Habitat. Medium subevergreen forests, high evergreen forest, flooded forests, “cenotes” (sinkholes or pits) near vegetation, forests with dense vegetation, savanna, and river basins, only in lowlands.

Food and Feeding. The Yucatan Vesper Rat eats on seeds, leaf buds, and fruits. It has been caught in traps baited with banana or mixture of oats and vanilla. In captivity, diet consisted of commercial rodent chow, supplemented with seeds, apple, banana, pear, orange, and guava.

Breeding. Female Yucatan Vesper Rats have been reported with elongated uteri in July and October, and lactating females have been found in February. They make nests in holes in trees, between branches, and in abandoned bird nests. In captivity, courtship takes place when a male approaches and smells a female’s genitals and begins a chase while emitting shrieks; after 15 seconds, the female remains still and copulation occurs. Litters are small (e.g. 15 individuals in eight litters); infants average 3-6 g and are altricial at birth. After birth, young attach to mothers’ teats until they are c.2 weeks old. Yucatan Vesper Rats can be separated into three age classes based on appearance and wear ofteeth, cranial sutures, soft hair, and cranial and somatic metrics.

Activity patterns. The Yucatan Vesper Rat is mainly nocturnal, arboreal, and often associated with man-made structures. It has been captured in dead trunks, vines, trees, coconut trees, and human constructions (walls, thatches, and rafters under the roofs).

Movements, Home range and Social organization. The Yucatan Vesper Rat is usually found 2 m aboveground.

Status and Conservation. Classified as Least Concern on The IUCN Red List. Although recorded infrequently, the Yucatan Vesper Rat has relatively wide distribution, is tolerant of a broad range ofhabitats, presumably has a large overall population, occurs in protected areas, and is unlikely to be declining at nearly the rate required to qualify for listing in a threatened category.

Bibliography. Alvarez-Castafieda et al. (2015), Aranda et al. (1997), Genoways et al. (2005), Hall (1981), Mac-Swiney etal. (2009), McCarthy (1993), Panti-May et al. (2015), Ramirez-Pulido, Gonzalez-Ruiz et al. (2014), Reid (2009), Vazquez (2016), Wilson & Cole (2000).