The south-western black rhinoceros (''Diceros bicornis occidentalis'') is a subspecies of the

black rhinoceros The black rhinoceros, black rhino or hook-lipped rhinoceros (''Diceros bicornis'') is a species of rhinoceros, native to eastern and southern Africa including Angola, Botswana, Kenya, Malawi, Mozambique, Namibia, South Africa, Eswatini, Tanzania ...

, living in southwestern

Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...

(northern Namibia and southern

Angola , national_anthem = " Angola Avante"() , image_map = , map_caption = , capital = Luanda , religion = , religion_year = 2020 , religion_ref = , coordina ...

, introduced to South Africa). It is currently listed as

near threatened A near-threatened species is a species which has been categorized as "Near Threatened" (NT) by the International Union for Conservation of Nature as that may be vulnerable to endangerment in the near future, but it does not currently qualify fo ...

by the IUCN. The biggest threat towards the subspecies is illegal

poaching Poaching has been defined as the illegal hunting or capturing of wild animals, usually associated with land use rights. Poaching was once performed by impoverished peasants for subsistence purposes and to supplement meager diets. It was set a ...

Taxonomy

This subspecies is often mistaken for either the extinct southern black rhinoceros ('' D. b. bicornis'') or the southeastern subspecies ('' D. b. minor''). However, the populations in the arid areas of northern Namibia and southwestern Angola represent a separate subspecies. The holotype specimen, a male, was about 16 months old when caught alive by a Mr. Müller in 1914 near the

Kunene River The Cunene (Portuguese spelling) or Kunene (common Namibian spelling) is a river in Southern Africa. It flows from the Angola highlands south to the border with Namibia. It then flows west along the border until it reaches the Atlantic Ocean. It ...

(

Kaokoveld The Kaokoveld Desert is a coastal desert of northern Namibia and southern Angola. Setting The Kaokoveld Desert occupies a coastal strip covering , from 13° to 21°S and is bounded by the Atlantic Ocean to the west, the Namibian savanna woodla ...

, border region between Namibia and Angola), and shipped to the

Tierpark Hagenbeck The Tierpark Hagenbeck is a zoo in Stellingen, Hamburg, Germany. The collection began in 1863 with animals that belonged to Carl Hagenbeck Sr. (1810–1887), a fishmonger who became an amateur animal collector. The park itself was founded by C ...

, the Hamburg

Zoo A zoo (short for zoological garden; also called an animal park or menagerie) is a facility in which animals are kept within enclosures for public exhibition and often bred for conservation purposes. The term ''zoological garden'' refers to z ...

, in Germany. After its death on 15 October 1916, its hide and skeleton was preserved at the Zoologisches Museum Hamburg (specimen no. 40056) and described as belonging to a new species, ''Opsiceros occidentalis'', by L. Zukowsky in 1922. ''Opsiceros'' is an invalid synonym of the genus ''

Diceros ''Diceros'' (Greek: "two" (dio), "horn" (keratos)) is a genus of rhinoceros containing the living black rhinoceros ''(Diceros bicornis)'' and at least one extinct species. Taxonomy ''Diceros'' is generally believed to have branched off from an ...

''.

Description

The south-western black rhino, like all black rhino subspecies, has a distinct prehensile lip and is a browser. Its appearance is similar to other subspecies, the most important difference to them is a relatively broad head behind the eyes and minor features in the

dentition Dentition pertains to the development of teeth and their arrangement in the mouth. In particular, it is the characteristic arrangement, kind, and number of teeth in a given species at a given age. That is, the number, type, and morpho-physiolog ...

. Other characters often mentioned, like body size or the straightness and size of the horns, are subject to

individual variation In biology, polymorphism is the occurrence of two or more clearly different morphs or forms, also referred to as alternative ''phenotypes'', in the population of a species. To be classified as such, morphs must occupy the same habitat at the s ...

. They also are most adapted to arid habitat and can be found in arid

savanna A savanna or savannah is a mixed woodland-grassland (i.e. grassy woodland) ecosystem characterised by the trees being sufficiently widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach the ground to ...

and desert

climate Climate is the long-term weather pattern in an area, typically averaged over 30 years. More rigorously, it is the mean and variability of meteorological variables over a time spanning from months to millions of years. Some of the meteorologi ...

Population and threats

Historically, this subspecies once roamed in

Angola , national_anthem = " Angola Avante"() , image_map = , map_caption = , capital = Luanda , religion = , religion_year = 2020 , religion_ref = , coordina ...

, and Namibia, but their current range has decreased. The stronghold of the species is primarily in Namibia. One to four specimens have been reported from Angola and others were introduced to South Africa. The total population is increasing and numbered to 1,920 animals in 2010, with 55.8% adults. Poaching due to increasing horn prices is considered the main threat to the population.

IUCN status

The IUCN considers the living northern Namibian black rhino populations to belong to the subspecies ''D. bicornis bicornis'', and does not recognize a separate ''D. b. occidentalis''. This synonymy, based upon du Toit (1987) was, however, considered erroneous by Groves and Grubb (2011), and ''D. b. occidentalis'' was re-established as a valid subspecies. As all southernmost populations of black rhinoceros were exterminated by the mid-19th century, ''D. b. bicornis'' is completely extinct today.

References

{{Taxonbar, from=Q13561007 Rhinoceroses Mammals described in 1922 Mammals of Namibia Mammals of Angola