Naked molerat

Heterocephalus glaber

SUBFAMILY

Georychinae

TAXONOMY

Heterocephalus glaber Ruppell, 1842, Shoa, Ethiopia.

OTHER COMMON NAMES German: Nacktmull.

PHYSICAL CHARACTERISTICS

Hairless except for scattered sensory hairs. Their skin is pinkish brown and wrinkled, their tails are longer than those of other bathyergids. The smallest of the mole-rats: mean body mass 1.2 oz (34 g). There is no sexual dimorphism but size varies with social status and dominant individuals can weigh up to 2.8 oz (80 g).

DISTRIBUTION

Widespread in arid regions of East Africa (Ethiopia, Somalia, and Kenya).

HABITAT

Arid regions with mean annual rainfall of under 15.6 in (400 mm). Rainfall is unpredictable. Favor fine sandy soils that become very hard in the dry season.

BEHAVIOR

Highly social (eusocial); colonies of up to 300 animals (mean 75), showing marked reproductive division of labor, and a workforce of nonbreeding animals. Socially induced infertility is mediated through aggressive behavior by the breeding female. Most nonbreeders never disperse or breed. Colonies often highly inbred; there is no incest avoidance. Occasional out-breeding occurs: dispersers are fat, highly sexed, attracted to foreign animals, have a strong urge to disperse.

FEEDING ECOLOGY AND DIET

Feed on geophytes located through cooperative searching for food. Colonies occupy the same home range for many years. Coprophagy (eating feces) performed by all colony members. The breeding female and the weaning pups also beg feces from colony members.

REPRODUCTIVE BIOLOGY

Only one female and a few males breed. The breeding female has a distinctive elongated body and up to seven pairs of nipples. She breeds throughout the year. Gestation: 66-74 days; mean litter size: 12 (range one to 28); up to four litters born annually. Multiple paternity of a litter can occur. Naked molerats are long-lived (over 28 years in captivity); the reproductive animals remain fertile to old age.

CONSERVATION STATUS

Not threatened.

SIGNIFICANCE TO HUMANS None known. ♦

Common name /

Physical

Habitat and

Conservation

Scientific name

characteristics

behavior

Distribution

Diet

status

Namaqua dune mole-rat

Color variable, blackish head, dark band

Prefer slightly consolidated

Northwestern South

Geophytes, and above-

Lower Risk/Near

Bathyergus janetta

mid-dorsally from neck to rump, sides

coastal dunes in arid areas

Africa, extending into

ground vegetation when

Threatened;

silvery. Size varies regionally, animals

with rainfall usually below

Namibia.

available.

threatened by

heavier inland than at coast. Sexually

13.5 in (350 mm). Solitary;

habitat

dimorphic: males about 15 oz (425 g),

breed seasonally in spring/

destruction from

females about 11 oz (315 g).

early summer. One to seven pups.

diamond mining

Silvery mole-rat

Color light silvery gray or fawn. Have

Favors grasslands and open

Southern Kenya,

Little known, does eat

Lower Risk/Near

Heliophobius argenteocinereus

more cheek teeth than other mole-rats

forest in mesic areas with

Tanzania, southwestern

geophytes.

Threatened

(6 upper and 6 lower). No sexual

annual rainfall about 35 in

Congo, northern

dimorphism, mean weight 5.6 oz

(900 mm). Solitary lifestyle.

Mozambique.

(160 g).

Mashona mole-rat

Color variable from blackish through seal

Scrub and open woodlands,

Includes eastern

Not known, includes

Not threatened

Cryptomys darlingi

brown to fawn, white head patch may be

mean annual rainfall exceeds

Zimbabwe, west and

geophytes and roots.

present. No sexual dimorphism: mean

27.3 in (700 mm). Social, in

central Mocambique.

weight 2.3 oz (64 g).

small colonies with a single

breeding pair. Aseasonal

breeders, gestation 56-

61 days, small litters

(maximum of three).

Giant Zambian mole-rat

Color light brown, small head patch

Miombo tropical woodland

Congo, northern

Geophytes, roots, some

Not threatened

Cryptomys mechowi

occasionally present. Heads are large.

and savanna with rainfall

Zambia, and central

invertebrates.

Sexual dimorphism apparent: males up

over 43 in (1,100 mm).

Angola.

to 21 oz (600 g), females 12.3 oz (350 g).

Social, at least eight in a

colony with a breeding pair.

Aseasonal reproduction.

Gestation about 100 days,

maximum litter size four.

Bocages mole-rat

Drab gray to silver gray. Mean head and

Little known of the habitat or

Western Angola and

Not known.

Not threatened

Cryptomys bocagei

body length 6 in (152 mm), no data for

behavior of this social mole-

possibly extending into

weight.

rat.

northwestern Namibia.

[continued]

Common name /

Physical

Habitat and

Conservation

Scientific name

characteristics

behavior

Distribution

Diel

status

Nigerian mole-rat

Deep sepia color, head patch may be

Nothing known of habitat.

Bauchi plateau in

Not known.

Lower Risk/Near

Cryptomys foxi

present. Mean head and body length:

Social with 12 animals

Nigeria, Ngaundere in

Threatened;

5.6 in (145 mm), no data for weight.

caught in one colony. No

Cameroon.

threatened by

other details.

habitat

destruction

Togo mole-rat

Color variable but generally pale. White

In Guinea and Doka wood-

Restricted distribution

Not known.

Lower Risk/Near

Cryptomys zechi

head patch sometimes present. Mean

lands. Occur in small colonies

between Oti and Volta

Threatened;

head and body length 6.5 in (167 mm),

but details not known.

rivers.

threatened by

no data for weight.

habitat

destruction

Ochre mole-rat

Brown to sepia color with white head

Savanna with low to

Sudan, and possibly

Not known.

Not threatened

Cryptomys ochraceocinereus

patch. Mean head and body length 7.8 in

moderate rainfall.

includes synonyms

(201 mm), no data for weight.

C. lecheifrom northern

Uganda and northern

Democratic Republic

of the Congo and

C. kummifrom Central

African Republic.

Highveld mole-rat

Recent genetic studies suggest that this

Highveld grasslands and

Endemic to highveld of

Grass roots and stolons

Not threatened

Cryptomys hottentotus

may be a separate species. Color silvery

savanna woodlands. Social,

South Africa, in North-

and geophytes.

pretoriae

fawn to seal gray. Head patch rarely

colonies up to 12 individuals

western, Gauteng, and

present. Body mass 3 oz (90 g). No

with a breeding pair. Seasonal

Mpumalanga provinces.

sexual dimorphism.

breeder (May to December),

maximum of three pups per

litter and two litters annually.

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