The rusty-breasted nunlet (Nonnula rubecula) is a species of near-passerine bird in the family Bucconidae, the puffbirds, nunlets, and nunbirds. It is found in Argentina, Brazil, Colombia, Ecuador, Guyana, Paraguay, Peru, Suriname, Venezuela, and possibly French Guiana. Taxonomy and systematics Taxonomists recognize the seven subspecies of rusty-breasted nunlet listed below. However, the species' taxonomy is unsettled. Some of the subspecies might be species in their own right, some might not be valid at all as separate taxa, and the nominate subspecies might actually represent two subspecies or species. N. r. tapanahoniensis Mees (1968) N. r. duidae Chapman (1914) N. r. interfluvialis Parkes (1970) N. r. simulatrix Parkes (1970) N. r. cineracea Sclater, PL (1881) N. r. simplex Todd (1937) N. r. rubecula Spix (1824) Description The rusty-breasted nunlet is long and weighs . The subspecies vary in structure and color from each other. In general, the more northerly subspecies have a longer and narrower bill and a shorter tail than the more southerly ones. The nominate subspecies has what amounts to two or three color morphs. Some members of it have plain dark gray-brown upperparts and wings. Their lores are rufous and they have a whitish band from the lores that joins a white ring around the eye. Their tail is dark brown. Their throat, breast, and flanks are brown with a reddish tinge and the abdomen is whitish. Other members of the nominate are paler and grayer, especially on the crown, but in the southeast are a darker brown with a warmer brown tail. Some have a bright orange-rufous (instead of brown) throat, breast, and flanks. N. r. tapanahoniensis has a very gray crown and a cinnamon tinge to the vent. N. r. duidae has a rufous chin. N. r. interfluvialis has a grayer tail and N. r. simulatrix a darker tail than the others. N. r. simplex is drab and dark while N. r. cineracea has warmer brown underparts. Distribution and habitat The rusty-breasted nunlet is found in two disjunct areas. The subspecies are distributed thus: N. r. tapanahoniensis, the southern Guianas and northern Brazil to the left bank of the lower Amazon River; "hypothetical" in French Guiana N. r. duidae, eastern Venezuela north of the Orinoco River N. r. interfluvialis, southern Venezuela and northern Brazil between the Orninoco and Negro rivers N. r. simulatrix, southeastern Colombia and northwestern Brazil between the Negro and Amazon rivers N. r.