Caecilia marcusi is a species of caecilian in the family Caeciliidae. It is found in the southwestern Amazon Basin in Bolivia and Brazil; its range is likely to extend into Peru. Caecilia marcusi is similar to Caecilia mertensi and could be its synonym.
Caecilia marcusi is a subterranean species inhabiting lowland tropical rainforest at elevations below 400m (1,300feet). It is locally threatened by habitat loss.