Adult: Species description based on Savage (2002). A very robust frog with short arms adn legs, and a small, pointed head (males to 61 mm, females to 67 mm). Dorsal: The dorsum is smooth and uniformly black or very dark grey in coloration. Ventral: The ventral surface is dark brown. Eye: The eye is black.
Breeding season: Breeding most likely occurs at least during the early part of the rainy season (Savage 2002). Egg: Eggs are black and yellow, and up to 80 may be deposited in shallow, water-filled depressions in the forest (Savage 2002). Tadpole: Tadpoles grow quite large (Savage 2002). The coloration is dark brown, except for the tail fins, which are clear (Savage 2002). The body is oval-shaped, with a long, thin tail (Savage 2002). The mouth is small and is directly forward, rather than dorsally or ventrally (Savage 2002). The tadpole has been described in detail by Donnelly, de Sa, and Guyer (1990).
Habitat: Lowland and premontane forest to 1600 m. Ecology: Nelsonophryne atterima inhabits leaf litter and burrows underground (Savage 2002). It is sometimes encountered under fallen logs or other debris (Savage 2002). Call: Unknown (Savage 2002). Karyotype: 2N = 26 (Leon-Azofiefa 1970) Type locality: Costa Rica