Cocha Antshrike is a very intriguing species in the genus Thamnophilus that, until relatively recently, was known form a single female specimen from northeastern Ecuador. Then, in the late 1980s, the species was “re-discovered” and the male, which had been undescribed to science, was found for the first time. It is now considered uncommon and local along slow-moving streams, and in flooded forest in extreme northeastern Ecuador. It is found in isolated pairs, and is often seen foraging low over water on exposed roots. Males are entirely black, with almost black facial skin around the eye. Females are entirely chestnut brown, with a black hood and breast. Males and females most similar in plumage to White-shouldered Antbird (Akletos melanoceps). Males differ by lacking the “white” shoulders and blue facial skin of White-shouldered Antbird, while female Cocha Antshrike also lack the blue facial skin. Although very similarly plumaged, the two species have radically different vocalizations. The primary song of Cocha Antshrike is a rapid series of 10-15 hollow notes, “oow-oow-oow-oow-oow-oow-oow-oow…,” compared to the mellow titmouse-like “peter-peter-peter” of White-shouldered Antbird. Also, as in other species of Thamnophilus antshrikes, males sit upright and “pump” their tails while calling. Not yet found in adjacent Peru.