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

subspecies In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...

of the black rhinoceros, living in southwestern Africa (northern Namibia and southern Angola, introduced to South Africa). It is currently listed as near threatened by the

IUCN The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...

. The biggest threat towards the subspecies is illegal poaching.

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 Ca ...

, the Hamburg Zoo, in Germany. After its death on 15 October 1916, its hide and skeleton was preserved at the

Zoologisches Museum Hamburg The University of Hamburg (german: link=no, Universität Hamburg, also referred to as UHH) is a public research university in Hamburg, Germany. It was founded on 28 March 1919 by combining the previous General Lecture System ('' Allgemeines Vor ...

(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-physiolo ...

. Other characters often mentioned, like body size or the straightness and size of the horns, are subject to individual variation. They also are most adapted to arid habitat and can be found in arid savanna and

desert A desert is a barren area of landscape where little precipitation occurs and, consequently, living conditions are hostile for plant and animal life. The lack of vegetation exposes the unprotected surface of the ground to denudation. About on ...

climates.

Population and threats

Historically, this subspecies once roamed in Angola, 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

considers the living northern Namibian black rhino populations to belong to the

''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