500.

Black-tailed Thallomys

Thallomys nigricauda

French: Thallomys a queue noire / German: Schwarzschwanz-Akazienratte / Spanish: Rata de acacias de cola negra

Other common names: Black-tailed Rat, Black-tailed Tree Rat

Taxonomy. Mus nigricauda Thomas, 1882,

“Hountop [= Hudup or Hutop] R[iver]., [west of Gideon], Great Namaqualand,” Namibia .

Thallomys nigricauda is poorly differentiated, with some morphometric overlap with 1. paedulcus . 1. damarensis is one of several synonyms of 1. nigricauda . Monotypic.

Distribution. Widespread in coastal W & SW Angola, Namibia, W Botswana, and NW South Africa.

Descriptive notes. Head-body 112-165 mm, tail 123-195 mm, ear 16-23 mm, hindfoot 23-28 mm; weight 38-85 g. The Black-tailed Thallomys is a medium-sized to large rodent with conspicuous facial markings. Fur is slate-gray above, with yellow wash, pale gray on flanks, sharply delineated from white belly, chin, and throat. Black facial mask extends from nose to around eyes. Upperparts of legs are pale gray. Feet are short, broad, with strong claws, and colored whitish above; forefeet have four digits, hindfeet with five digits, fifth digit elongated (nearly as long as second). Tail is long (c.120% of head-body length), covered with short black hairs, ending in weak tuft of longerhairs. Females have 1+2 = 3pairs of nipples. Karyotype 2n = 47-50.

Habitat. Arid acacia ( Acacia, Fabaceae) savanna.

Food and Feeding. Folivorous, feeding on leaves of Acacia (Fabaceae), Boschia and Grewia (both Malvaceae), Terminalia (Combretaceae), Dichrostachys (Fabaceae), and Ziziphus (Rhamnaceae), as well as young pods of Acacia . In North West province of South Africa, this rodent showed strong preference for two acacia species, A. mellifera and A. luederitzii . Occasionally eats insects. Forages for longer periods during breeding season compared with non-breeding period.

Breeding. The Black-tailed Thallomysis a seasonal breeder, with pregnant females and juveniles recorded in summer and autumn months. Litter size at estimated 30 days was 1-4 (mean 1-8).

Activity patterns. The Black-tailed Thallomys is nocturnal and arboreal.

Movements, Home range and Social organization. Contrary to earlier observations that Black-tailed Thallomys may live communally or in extended family groups, a radio-tracking study in North Westprovince showed that individuals live solitarily or with young offspring, and probably have promiscuous mating system. They make nests in branches of Acacia trees and shrubs. During breeding season, males have larger home ranges of 8-10 ha that encompass about eight nests of females. Nursing females have very small ranges ofless than 0-03 ha. During non-breeding season, males had smaller ranges (1-2 ha) that were still larger than those of females (0-1-0-3 ha).

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

Bibliography. Coleman & Downs (2010), Eccard et al. (2004), Gordon (1987), Happold (2013a), Loveridge et al. (1991), Meyer, Kohnen & Brandl (2010), Meyer, Raudnitschkaet al. (2008), Meyer, Steinhauser & Brand! (2007), Monadjem et al. (2015), Taylor et al. (1995).