402.

Angoni Vlei Rat

Otomys angoniensis

French: Otomys angoni / German: Angoni-Lamellenzahnratte / Spanish: Rata de laguna de Angoni

Taxonomy. Otomys irroratus angoniensis Wroughton, 1906,

“M’ Kombhuie, B.C.A. Alt. 8000’ [= 2591 m].” Restricted by W. F. H. Ansell and R. J. Dowsett in 1991 to “Matipa Forest, Malawi.”

Three subspecies are recognized.

Subspecies and Distribution.

O. a. angoniensis Wroughton, 1906 — S Uganda, SW Kenya, N Tanzania, Malawi, scattered in Mozambique, and C & E Zimbabwe.

O.a.maximusRoberts,1924—E&SEDRCongo,SWAngola,W&CZambia,CapriviStripinNamibia,andNBotswana.

O. a. tugelensis Roberts, 1929 — extreme SE Botswana, NE South Africa, and Swaziland.

Descriptive notes. Head—body 124-192 mm, tail 40-100 mm, ear 15-25 mm, hindfoot 21-32 mm; weight 60-182 g. The Angoni Vlei Rat is large and robust, with large blunt head, short tail, and shaggy fur. Dorsum is pale to dark grayish buff above and dark gray below. Tail is short (¢.55% of head-body length), darker above than below and sparsely haired. Ears are small and close to body. Females have two pairs of nipples. Upper incisors have one deep groove, and lower incisors have one deep and one shallow groove (latter is absent in subspecies maximus). M, has four laminae, and M” has 6-7 laminae (almost always seven). The Angoni Vlei Rat, Sloggett’s Vlei Rat ( O. sloggetti), and the Western Vlei Rat ( O. occidentalis) have slit-shaped (as opposed to round) petrotympanic foramen.

Habitat. Mesic grassland and savanna habitats from sea level to foothills and lower slopes of mountains associated with Rift Valley. Where the Angoni Vlei Rat co-occurs with the Southern African Vlei Rat ( O. irroratus), they are associated with plants on drier soils, but the Southern African Vlei Rat typically is associated with wetter habitats closer to water.

Food and Feeding. Diet mostly contains grasses but can also include dicotyledonous plants and bark of trees and shrubs (e.g. Lantana, Verbenaceae and Eucalyptus, Myrtaceae). Its long spiraled intestine, complex cecum, and laminate molars are adaptations for strict herbivory.

Breeding. Females are polyestrous. In Kenya, breeding occurs year-round, but in Malawi and South Africa, it is restricted to wet season. Females have 1-5 embryos, and litters in captivity have 2-5 young. Gestation is 37 days. Young are born precocial, with erupted incisors capable of nipple-clinging on their mother.

Activity patterns. Angoni Vlei Rats can be diurnal, crepuscular, or nocturnal, possibly depending on intensity of owl predation.

Movements, Home range and Social organization. Angoni Vlei Rats construct grass nests and make distinctive runways in grass. Although trap-shy and rarely collected, densities may reach 30 ind/ha.

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

Bibliography. Ansell & Dowsett (1991), Bronner & Meester (1988), Davis (1973), Hanney (1965), Happold (2013a), Monadjem et al. (2015), Perrin & Curtis (1980), Phillips et al. (1997), Taylor & Green (1976).