The quagga is an extinct subspecies of the plains zebra, which was once found in great numbers in South Africa's Cape Province and the southern part of the Orange Free State. It was distinguished from other zebras by having the usual vivid marks on the front part of the body only. In the mid-section, the stripes faded and the dark, inter-stripe spaces became wider, and the rear parts were a plain brown. The name comes from a Khoikhoi word for zebra and is onomatopoeic, being said to resemble the quagga's call. The only Quagga to ever have been photographed alive was the Regent's Park Zoo mare in London (pictured above).
The quagga was originally classified as an individual species, Equus quagga, in 1788. Over the next fifty years or so, many other zebras were described by naturalists and explorers. Because of the great variation in coat patterns (no two zebras are alike), taxonomists were left with a great number of described "species", and no easy way to tell which of these were true species, which were subspecies, and which were simply natural variants.
Long before this confusion was sorted out, the quagga had been hunted to extinction for meat, hides, and to preserve feed for domesticated stock. The last wild quagga was probably shot in the late 1870s, and the last specimen in captivity, a mare, died on August 12, 1883 at the Artis Magistra zoo in Amsterdam. Because of the great confusion between different zebra species, particularly among the general public, the quagga had become extinct before it was realized that it appeared to be a separate species.
The quagga was the first extinct creature to have its DNA studied. Recent genetic research at the Smithsonian Institution has demonstrated that the quagga was in fact not a separate species at all, but diverged from the extremely variable plains zebra, Equus burchelli, between 120,000 and 290,000 years ago, and suggests that it should be named Equus burchelli quagga. However, according to the rules of biological nomenclature, where there are two or more alternative names for a single species, the name first used takes priority. As the quagga was described about thirty years earlier than the plains zebra, it appears that the correct terms are E. quagga quagga for the quagga and E. quagga burchelli for the plains zebra.
Info copied and pasted from : http://en.wikipedia.org/wiki/Quagga