The Sumatran muntjac is a small deer that can be the size of a large dog. Its taxonomy is unresolved: it has been treated either as a distinct species, Muntiacus montanus, or as a subspecies of the common muntjac (Wikipedia, general species account).
It was discovered in 1914 and had not been sighted since 1930 until one was snared and freed from a hunter's snare in Kerinci Seblat National Park, Sumatra, in 2002. Two other animals have since been photographed in the park (Wikipedia, general species account).
Description: Wildlife of Sumatra guide, Wildlife of Everywhere (wildlifeofeverywhere.com); general species information paraphrased from Wikipedia (CC BY-SA)
Mammals of the World