What is "variable antshrike"

n. A passerine bird of the antbird family, in species (taxlink Thamnophilus caerulescens species).

The variable antshrike (Thamnophilus caerulescens) is a species of bird in the family Thamnophilidae found widely in South America. It is, as its common name suggests, arguably the species of antbird with the most variable plumage, leading to speculations that it comprises more than one species, but presently available evidence suggests this assumption is incorrect.