A new species of Sibon (Serpentes, Dipsadini) from French Guiana and amended diagnosis of Sibon nebulatus

Specimens of snakes from Mexico to northeastern Brazil have been assigned to the taxon Sibon nebulatus. Recent molecular data confirmed the previous suspicions that these specimens in fact belong to distinct species. After examination of the holotype and recently collected specimens, we provide an amended diagnosis and restrict the range of S. nebulatus to northern South America, implying that Central American populations belong to one or several undescribed species.

We also describe Sibon nigralbus sp. nov., a new species from the Guiana region. Further investigation is needed to clarify the status of populations in Pará state, Brazil, and in the Magdalena valley in Colombia, where additional species possibly occur.