484.

Western Amazonian Water Rat

Nectomys apicalis

French: Nectomys de Peters / German: \WWestamazonas-Wasserratte / Spanish: Rata de agua del Amazonas occidental

Other common names: Western Amazonian Nectomys

Taxonomy. Nectomys apicalis Peters, 1861, “Guayaquil.” Corrected by P. Hershkovitz in 1944 as “Tena, Napo-Pastaza Province, Ecuador; altitude, 512 meters.” This species is monotypic.

Distribution. E Ecuador, E Peru, and W Brazil (Amazonas State).

Descriptive notes. Head-body 145-270 mm, tail 161-272 mm, ear 15-30 mm, hindfoot 37-58 mm; weight 141-430 g. See general characters of the genus under the Trinidad Water Rat (N. palmipes) account. The Western Amazonian Water Rat has dark mid-dorsal band covering less than one-third of dorsal breadth. Dorsum is ocherous buff, with mix of cinnamon brown or dark brown; underparts are pale gray or ocherous gray. Mystacial vibrissae are long but do not reach tips of ears. Tail is brown, with keel brown or mixed with gray. Skull is robust; lacrimals are equally in contact with maxilar and frontal bones. Incisors are opisthodonts; molars are robust. Chromosomal complement is 2n = 38-42, FNa = 40-41.

Habitat. Undisturbed or second growth forests along rivers and streams at elevations of 105-3400 m.

Food and Feeding. Dental morphology and habits of the closely related Atlantic Water Rat (N. squamipes) suggest that the Western Amazonian Water Rat eats small vertebrates and invertebrates, fungi, and plant material.

Breeding. Adult male Western Amazonian Water Rats collected along Rio Jurua (Brazil) between August and November were scrotal with enlarged testes and vesicular glands, and adult females were either pregnant or lactating.

Activity patterns. Trapping data of Western Amazonian Water Rats suggests nocturnal activity. They are semi-aquatic and use water for foraging and refuge.

Movements, Home range and Social organization. No information.

Status and Conservation. Classified as Least Concern on The IUCN Red List.

Bibliography. Bonvicino & Weksler (2015), Chiquito (2015), Ernest & Mares (1986), Gomez-Laverde, Rivas & Weksler (2016), Hershkovitz (1944), Musser & Carleton (2005), Patton et al. (2000), Prevedello et al. (2010).