Bluish Flowerpiercer (Diglossa caerulescens) - HBW 16, p. 278

Taxonomy: Diglossopis caerulescens P. L. Sclater, 1856, Caracas, Venezuela.
Genus has sometimes been placed in Coerebidae or Parulidae or even, because of an apparent close relationship to Acanthidops, in Emberizidae. Molecular phylogenies indicate that it is most closely related to Xenodacnis and to Acanthidops, Haplospiza and Catamenia (the last three genera currently placed in Emberizidae), and that all clearly belong in present family. Members of this clade may also be closely related to the Oreomanes–Conirostrum clade. This species, along with D. indogotica, D. glauca and D. cyanea, has sometimes been placed in separate genus, Diglossopis, on grounds of some important anatomical features (of corneous tongue, bony palate, maxillo-palatines and mandible, and structure of rhamphotheca), all of which may set them apart from present genus; these four species, with a proportionately smaller bill hook, may have evolved only once, while all other flowerpiercers (with larger hook) may have evolved multiple times; recent molecular-genetic data, however, indicate that these four “small-billed” species do not form a monophyletic group, and all flowerpiercers are best retained in a single genus. Some races of present species weakly differentiated; intermedia differs only slightly from saturata (to N of it) and pallida (to S), being intermediate between the two, and may not merit recognition. A slightly paler specimen of saturata from El Chaco, on E slope in Ecuador, is perhaps intermediate between that race and media. Some authors have suggested that all specimens from C & W Andes of Colombia and adjacent NW Ecuador (currently placed in saturata) belong to an as yet unnamed race, and that specimens from most of Ecuadorian range of media (except SW Ecuador) represent an additional undescribed race; further study required. Seven subspecies tentatively recognized.