Insulacebus is an extinct monotypic genus of New World monkey found on the island of Hispaniola from Late Quaternary deposits. Fossils of the type species I. toussaintiana have been recovered from the Plain of Formon, Department du Sud, southwestern Haiti. The body mass of the monkey was estimated between 4,159 and 5,443 grams (9.169 and 12.000 lb). The dentally primitive I. toussaintiana was likely derived from a fauna that was evolving on the mainland before the Miocene monkey bed of the Honda Group of central Colombia, and stems from a pre-Middle Miocene colonization from the South American mainland.