Water deer

The water deer (Hydropotes inermis) is a small deer species native to Korea and China. Its prominent tusks, similar to those of musk deer, have led to both subspecies being colloquially named vampire deer in English-speaking areas to which they have been imported. It was first described to the Western world by Robert Swinhoe in 1870. There are two subspecies: the Chinese water deer (H. i. inermis) and the Korean water deer (H. i. argyropus). The water deer is superficially more similar to a musk deer than a true deer; despite anatomical peculiarities, including a pair of prominent tusks (downward-pointing canine teeth), and its lack of antlers, it is classified as a cervid. Yet, its unique anatomical characteristics have caused it to be classified in its own genus (Hydropotes) as well as historically its own subfamily (Hydropotinae). However, studies of mitochondrial control region and cytochrome b DNA sequences placed it near Capreolus within an Old World section of the subfamily Capreolinae, and all later molecular analysis show that Hydropotes is a sister taxon of Capreolus. The genus name Hydropotes derives from the two ancient Greek words ὕδωρ (), meaning "water", and πότης (), meaning "drinker", and refers to the preference of this cervid for rivers and swamps. The etymology of the species name corresponds to the Latin word inermis meaning unarmed, defenceless—itself constructed from the prefix in- meaning without and the stem arma meaning defensive arms, armor—, and refers to the water deer's lack of antlers. Archeological studies indicate water deer was once distributed among much broader range than currently during the Pleistocene and the Holocene periods; records have been obtained from eastern Tibet in west, Inner Mongolia and northeastern China in north, southeastern Korean Peninsula (Holocene) and Japanese archipelago (Pleistocene) in east, southern China and northern Vietnam in south. Water deer also inhabited Taiwan historically, however this population presumably became extinct as late as the early 19th century.