A new species of Colostethus is described from Kaieteur National Park, Guyana, South America. The new species can be distinguished from close relatives by the presence of a median lingual process, first finger equal to second, Finger III not distinctly swollen but all fingers slightly swollen in males, presence of fringes on fingers, presence of a dorsolateral stripe from posterior corner of eye, absence of an oblique lateral stripe, and differences in tadpole morphology, colouration and pattern, vocalizations and ecology. This is only the second species of Colostethus known to provide maternal care for tadpoles.