Line-cheeked Spinetail (Cranioleuca antisiensis) - HBW 8, p. 297

Taxonomy: Synallaxis antisiensis P. L. Sclater, 1859, Cuenca, Azuay, Ecuador.
Sister-species to C. baroni, and very likely conspecific; although populations at extremes of ranges are clearly different, the two grade into one another in step-clinal manner, making it difficult or impossible to determine to which taxon certain populations should be assigned (see page 187), this applying also to an apparently undescribed population in Amazonas (N Peru); thorough, quantitative analysis of all parameters (including plumage, morphometrics, vocalizations, genetics) required in order to elucidate the situation with regard to geographical differentiation and speciation. Both are part of a superspecies that also includes C. erythrops, C. demissa, C. hellmayri and C. curtata; all share plumage similarities and mostly lower montane distribution, and their close relationship is consistent with recent genetic data. Some authors, however, have considered them to belong to a superspecies that also includes C. subcristata, C. pyrrhophia, C. henricae, C. obsoleta, C. pallida and C. albicapilla, but such a relationship is not supported by recent genetic findings. Two subspecies recognized.