Castelnau's antshrike

Castelnau's antshrike (Thamnophilus cryptoleucus) is a species of bird in subfamily Thamnophilinae of family Thamnophilidae, the "typical antbirds". It is found in Brazil, Colombia, Ecuador, and Peru.

Castelnau's antshrike is 16 to 18 cm (6.3 to 7.1 in) long and weighs 30 to 35 g (1.1 to 1.2 oz). Members of genus Thamnophilus are largish members of the antbird family; all have stout bills with a hook like those of true shrikes. This species exhibits slight sexual dimorphism. Adult males are mostly black. They have a mostly hidden white patch between their scapulars, white tips on the scapulars, white tips and edges on their wing coverts, sometimes very small white tips on their flight feathers, and white underwing coverts. Their flanks and belly are dark gray. Adult females are similar to males but their scapulars and wing coverts are entirely black. Subadults are similar to adult females but browner. Both sexes have a brown iris, a black bill, and blue-gray legs and feet.