467.

Venezuelan Marsh Rat

Holochilus venezuelae

French: Oryzomys du Venezuela / German: Venezuela-Sumpfratte / Spanish: Rata de marisma de Venezuela

Taxonomy. Holochilus venezuelae J. A. Allen, 1904, El Llagual, Venezuela.

This species is monotypic.

Distribution. N Venezuela from Lago Maracaibo E to lower Orinoco River Basin.

Descriptive notes. Head-body 130-226 mm, tail 124-194 mm, hindfoot 36— 48 mm; weight 130-2 g (mean males) and 131-1 g (mean females). Species in Holochilus are characterized by morphological specializations for semi-aquatic life and herbivorous diet. They have minor differences in dorsal coloration, but great variation in ventral coloration that varies from white to ocherous. They are characterized by long and dense pelage, long tails, long and robust webbed hindfeet, strong skulls with narrow interorbits, massive jaws, and laminated tetralophodont molars. Dorsum of the Venezuelan Marsh Rat is reddish to brown, lighter on sides, with lower back and flanks reddish. Venter is buffy gray. Tail is unicolored, more hairy apically. Chromosomal complement is 2n = 44, FN = 56.

Habitat. Savannas.

Food and Feeding. The Venezuelan Marsh Rat eats mainly grasses and agricultural crops, with small amounts of Cyperaceae, dicotyledonous plants, and invertebrates. Young individuals usually eat more invertebrates, and adults eat more seeds and stems. Diets do not differ between sexes.

Breeding. Mean numbers of embryos were 5-8-7-4/litter in different studies. Gestation lasts ¢.29 days.

Activity patterns. Observations of the Venezuelan Marsh Rat suggests nocturnal activity.

Movements, Home range and Social organization. Home ranges of male and female Venezuelan Marsh Rats do not differ and are 0-6-1-3 ha.

Status and Conservation. Not assessed on The IUCN Red List. The Venezuelan Marsh Rat occurs at high densities and is considered an agricultural pest in Venezuela, so it is probably best classified as Least Concern.

Bibliography. Aglero (1978), Aguero et al. (1985), Aguilera (1987), Aguilera & Pérez-Zapata (1989), Cartaya (1983), Cartaya & Aguilera (1984, 1985), Eiris & Barreto (2009), Goncalves et al. (2015), Martino & Aguilera (1989).