Adult: Species description based on Ibanez et al (1995). Medium-sized frog (males to 30 mm, females to 40 mm).
Dorsal: Dorsal surface smooth and typically dark brown or black with variable bright green markings. The dorsal surface of females may be solid olive-brown.
Ventral: The ventral surface of males is white, often with small black markings, particularly on the throat. The ventral surface of females is orange, sometimes shades of white, yellow, or green are also present.
Concealed surfaces: Males have a thin dark line running the length of the body along the lateral surface. The line may be clearly defined in some specimens, whereas in others it is less prominent or broken. No females have been observed with this feature.
Eye: Pupil horizontal.

Breeding season: An amplectant pair was observed in November (Ibanez et al 1995).

Habitat: Primary rainforest in the lowlands of central Panama to 730 m.
Ecology: This species is active during the day and may be found among the rocks and debris of streams in primary forest (Ibanez et al 1995). Ibanez et al (1995) observed that the skin color of the frogs resembled the color of the silt covering the surface of rocks and the streambed, making detection of the frogs difficult.
Call: A sonogram of the advertisement and release calls of A. limosus can be found in Ibanez et al (1995).
Type locality: "en las orillas de la Quebrada San Antonio (09° 24′ 00″ N, 79° 31′ 07″ O), aproximadamente a 180 m sobre el nivel del mar, cerca del poblado San Juan de Pequení, Provincia de Panamá"