We describe a new species of the caecilian genus Microcaecilia (Amphibia: Gymnophiona: Caeciliidae) from the Lely Mountains, Suriname and provide new information about the identification and distribution of species of Microcaecilia across the Guiana Shield. The new species, M. grandis, is large (318 mm total length), has many premaxillary-maxillary teeth (>20), and has bicuspid vomeropalatine teeth. We determined that specimens from Suriname previously assigned to M. unicolor (Duméril, 1864) were misidentified and that M. unicolor is currently known only from French Guiana.