A new species of Allobates (Anura: Aromobatidae) from the Tapajós River basin, Pará State, Brazil.

We describe a new species of Allobates from the south of eastern Amazonia, Brazil. This species inhabits fluvial springs and the banks of small streams in terra-firme forests along the Tapajós River basin. Average snout-to-vent length is 17.78 mm (range 16.09-19.59 mm) among males and 19.50 mm (range 17.97-20.84 mm) among females. Surface of dorsum is marked by a distinct dark color pattern, with three convex areas, triangle and diamond-shaped. The species has a diffuse pale dorsolateral line (absent in some specimens), while the oblique lateral bar is defined. Dark-brown transversal stripes are present on femoral and tibial dorsal surfaces, which align with each other in live specimens when at rest. Tadpoles have short papillae on anterior (8-10 papillae on each side) and posterior labium (>30 papillae). Posterior labium is projected to the front, hiding posterior tooth rows. Eggs are deposited in nests on rolled or cranked dead leaves on the forest floor. Egg membranes and jelly-nests are transparent. Advertisement calls are mainly characterized by the continuous emission of single notes that might shift sporadically to note-pairs, emitted during short periods. Notes are split by regular silent intervals, with peak frequency ranging between 4273-4867 Hz.