Subfamily Mystromyinae
white-tailed mouse

Mystromyinae is an Old World nesomyid subfamily that has a single genus and species, the white-tailed mouse (Mystromys albicaudatus). (Musser and Carleton, 2005)

Mystromys albicaudatus is found in South Africa and Swaziland. (Nowak, 1999)

These rodents inhabit dry savannahs and semidesert. (Nowak, 1999)

In the past, most authors have placed Mystromys in the subfamily Cricetinae. A few authors recognized the uniqueness of the genus (Ellerman 1941, Vorontsov 1966), and Vorontsov (1966) placed it in a monotypic cricetine tribe, Mystromyini. In 1973, Lavocat went even further, giving Mystromys its own subfamily in the family Nesomyidae; he saw it as part of a lineage of rodents derived from an ancient group of African cricetids, the afrocricetodontines. Although later authors kept Mystromys in Cricetinae (e.g. Skinner and Smithers 1990), molecular evidence has shown that Mystromys falls within a clade that contains Dendromurinae, Cricetomyinae, and Petromyscinae (Michaux et al. 2001, Jansa and Weksler 2004), and is not closely related to cricetines after all. (Carleton and Musser, 1984; Ellerman, 1941; Jansa and Weksler, 2004; Lavocat, 1973; Michaux, Reyes, and Catzeflis, 2001; Musser and Carleton, 1993; Musser and Carleton, 2005; Skinner and Smithers, 1990; Vorontsov, 1966)

White-tailed mice are rat-like in overall appearance, with slender limbs and large, prominent ears. Their long, soft fur ranges from brown to buffy-gray on the dorsal surface, with interspersed black-tipped hairs. The ventral surface, feet, and tail are white, and the ears are dark brown. The tail is covered with stiff, short hairs. The head and body length of white-tailed mice ranges from 105 to 184 mm, and the tail length ranges from 50 to 97 mm. They weigh 75 to 111 grams, males tend to be about 20 grams heavier than females (Becker and Middleton 1979). The incisors of mystromyines are pale yellow and the surfaces lack grooves. Mystromyines have no cheek pouches, and they have two pairs of inguinal mammae. (Becker and Middleton, 1979; Nowak, 1999)

White-tailed mice live to about six years in captivity; lifespan in the wild has not been reported. (Nowak, 1999)

White-tailed mice are nocturnal, strictly terrestrial rodents that rest by day in holes or cracks in the ground. Sometimes they shelter in meerkat burrows. They are reportedly most active when it rains. (Hallett and Meester, 1971; Nowak, 1999)

White-tailed mice probably have keen olfactory and auditory abilities, as they have been observed rearing up on their hind legs and sniffing when disturbed. Young mystromyines probably have good senses of smell and touch from birth. They squeal when they are separated from their parents and begin responding to sound at 13 to 15 days of age. (Hallett and Meester, 1971)

Mystromyines eat insects, seeds, and other plant matter. In captivity, they will eat meat and carrots. Adults have also been observed eating the carcasses of dead offspring. (Hallett and Meester, 1971; Nowak, 1999)

Barn owls (Tyto alba) are reported predators of white-tailed mice. Other likely predators include other owl species, snakes, and nocturnal mammalian predators Young white-tailed mice cling to the nipples of their mothers continuously for the first few weeks of life, which increases their chance of survival because adult females can more easily evade predators than can immobile neonates. Even after they are no longer nursing constantly, youngsters seek shelter under their parents when alarmed. Parents sometimes defend their offspring by biting viciously. (DeGraaff, 1997; Hallett and Meester, 1971)

Because they are omnivores, mystromyines are primary and higher-level consumers. They are also food for animals at higher trophic levels, such as barn owls. (DeGraaff, 1997)

There are no known negative effects of white-tailed mice on humans.

White-tailed mice are easy to breed in captivity and are therefore used in laboratories for disease research. (Hallett and Meester, 1971)

White-tailed mice are currently considered endangered by the IUCN; though their range is relatively large, population density is low and populations are highly fragmented. There are protected areas in some parts of the species' range, but habitat loss to grazing, agriculture, and timber plantations is a major threat. Surveys of white-tailed mouse populations and research into their life history characteristics are needed, as is public awareness about their plight. (Coetzee and Monadjem, 2004)