The Guianan squirrel monkey (Saimiri sciureus) is a species of squirrel monkey from Guiana, Venezuela and Brazil. S. sciureus formerly applied to Humboldt's squirrel monkey and Collins' squirrel monkey, but genetic research in 2009 and 2015 revealed that these are distinct species. == Taxonomy == Several now-separate squirrel monkey species were formerly considered a single species, Saimiri sciureus, generally known as the common squirrel monkey, with a wide range in the northern half of South America. A 2009 genetic study by Carretero-Pinzón, et al indicated Humboldt's squirrel monkey, S. cassiquiarensis, from Colombia, Peru and Ecuador, which had been considered a subspecies of S. sciureus, was actually more closely related to other squirrel monkey species. A 2015 genetic study by Lynch Alfaro, et al revealed that Collins' squirrel monkey, S. collinsi, from northeastern Brazil, which had also been considered a subspecies of S. sciureus, should also be treated as a separate species. This left S. sciureus to apply to the squirrel monkeys in northern Brazil and the Guianas. Lynch Alfaro's study also revealed that despite the gap in their ranges, the squirrel monkey species most closely related to the Guianan squirrel monkey is the Central American squirrel monkey of Costa Rica…