The Omilteme cottontail (Sylvilagus insonus ) is a cottontail rabbit found only in the state of Guerrero, Mexico in the mountain range of Sierra Madre del Sur. Belonging to the family Leporidae, it is one of fourteen species in the genus Sylvilagus, a genus restricted to the New World. The Omilteme cottontail is considered one of the most endangered rabbit species in the world and is only known and been described by very few specimens.
The Omilteme cottontail is a large rabbit with long ears (greater than 53mm from the base), hind feet of medium length (greater than 81mm) and a short tail. This rabbit has a very distinct coat colouration. Around the nose and orbital area, the coat is a dull grey. The convex surface of the ears is a dark brown-black colour and the black is also very concentrated along the anterior border as well as on the tips of the ears. The dorsal side is rufous (a red-brown colour) mixed with black while the sides are grey-black in colour. The medium-sized hind feet are white on the dorsal side and the soles are a dark brown. The dorsal side of the tail is reddish-black while the ventral side is white
S. insonus is endemic to Mexico and is found only in Sierra Madre del Sur of the State of Guerrero. It is only known from its type locality, Omiltemi Ecological State Park, located in a wooded summit of a semi-isolated mountain range. Its habitat range is 2,133-3048m elevation. Surrounding the wooded area is the village of Omiltemi at 2,332m above sea level (in Municipio Chilpancingo). The Omilteme cottontail is therefore restricted to a region of less than 500 square kilometres.
The Omilteme cottontail lives at the summit of a mountain range which has steep slopes and ravines covered with dense cloud forests. Some pine and pine-oak forests are present as well. It shares its habitat with 37 other mammal species. In the dense cloud forests, the rabbit lives amongst the undergrowth where it makes runways and burrows under objects such as rocks.
It is a mainly nocturnal mammal.
According to the IUCN Red List of Threatened Species, the Omilteme cottontail is data deficient. The major threats to the survival of this species are poaching and habitat destruction caused by deforestation. This rabbit went unreported in the wild from the early 1900s to the 1990s; however, two specimens were captured in 1998, confirming that the species was still extant. The rabbit is among the 25 "most wanted lost" species that are the focus of Global Wildlife Conservation's "Search for Lost Species" initiative.
