Strong-billed Woodcreeper (Xiphocolaptes promeropirhynchus) - HBW 8, p. 415

Taxonomy: Dendrocolaptes promeropirhynchus Lesson, 1840, no locality = “Bogotá”, Colombia.
Sometimes considered to form a superspecies with X. albicollis. Races usually divided into three groups, treated as separate species by some authors: “emigrans group” (Central America), “promeropirhynchus group” (mountains of W & N South America), and “orenocensis group” (primarily Amazonian lowlands). Populations in mountains of N South America may be closer to those in Amazonian lowlands than to those in Peruvian and Bolivian Andes; affinities of race crassirostris problematic, possibly allied with “orenocensis group” but occurring W of Andes. Assessment of geographical variation complicated by marked individual variation within taxa in almost all geographically variable characters. Race ignotus sometimes merged with nominate; rostratus possibly a junior synonym of fortis; virgatus poorly defined, and intergrades with nominate on E slope of C Colombian Andes; and sanctaemartae very similar to procerus; racial identity of birds in Guianan lowlands uncertain, tentatively placed with tenebrosus. Thorough taxonomic revision needed. If by nothing else, Central American, Andean and Amazonian populations united by vocalizations that are remarkably similar, given degree of morphological differentiation. Published records from N Argentina apparently referable to misidentified Dendrocolaptes picumnus. Twenty-five subspecies recognized.