Brazil's Bahia Spinetail has been found to be invalid and – unusually for South America – lumped with the more widespread Rufous-tailed Spinetail.
Rufous-tailed Spinetail Synallaxis ruficapilla – found from the Rio Jequitinhonha south – is the most widespread of a species complex that also includes Pinto's Spinetail S infuscata – endemic to north-eastern Brazil – and Bahia Spinetail S whitneyi – found north of the Rio Jequitinhonha – which is somewhat intermediate between the other two. Bahia spinetail is paler than Pinto's but darker than Rufous-capped, and was believed to ahve distinctive vocalisations affriming its status as a 'good' species.
The researchers found that Bahia Spinetail differed in no way diagnostically from Rufous-tailed in either voice or plumage. In short, it was clearly part of the geographical variation in plumage and voice of Rufous-tailed. Pinto's Spinetail, however, remains a regional endemic with diagnostic vocalisations, an amber supercilium, and ten tail feathers rather than the eight found in S ruficapilla.
Stopiglia, R, Raposo, M A and Teixeira, D M. 2012. Taxonomy and geographoc variation of the Synallaxis ruficapilla Vieillot, 1819 speceis-complex (Aves: Passeriformes: Furnariidae). Journal of Ornithology doi:10.1007/s10336-012-0886-3.