Minor geographic variation in some morphological and plumage features has been reported, and up to three subspecies have been recognized (Storer 1970; see also Systematics). Vuilleumier (1984), however, demonstrated that most of this variation is clinal and that the species is best considered to be monotypic. Oremanes fraseri from Colombia and Ecuador have a darker crown and back, while more southern populations in Peru and Bolivia tend to have lighter plumage. Following Gloger’s rule this clinal variation in plumage is correlated with the precipitation of each respective habitat, such that darker morphs appear in areas with more rainfall (e.g. Ecuador), and lighter morphs in drier areas (e.g. Bolivia), along with intermediate morphs (e.g. Peru) (Vuilleumier 1984, Fjeldså and Krabbe 1990). However, there appears to be discontinuities in the plumage patterns of certain features (i.e. underparts, superciliary stripe), so that the geographical variation in plumage appears to be more checkerboard than clinal (Vuilleumier 1984). Vuilleumier (1984) noted some indications of clinal variation in culmen length, such that the southernmost Giant Conebills were larger than northern populations, but did not have enough specimens to test the gradation statistically.
Oreomanes is a currently recognized as a monotypic genus with O. fraseri as the sole representative. The taxonomy of Oreomanes was a topic of much debate during the 20th century. Oreomanes fraseri was described by Sclater (1860: 75), and currently is recognized as a monotypic genus. A second species, O. binghami, was described by Chapman (1919, locality 20, table 1, fig. 1), but was later identified as an immature O. fraseri specimen by Hellmayr (1919: 11-12). The third and last taxon to be described in Oreomanes was the subspecies O. fraseri sturninus by Bond and Meyer de Schauensee (1939), which corresponded to the lighter plumage morphs of Bolivia. Zimmer (1942) recognized three subspecies to account for geographic variation in plumage: O. f. fraseri (Ecuador and southern Colombia); O. f. binghami (Peru); and O. f. sturninus (Bolivia). Vuilleumier (1984) showed that the geographical variation corresponding to these subspecies is minor and clinal or checkerboard in nature, however, suggesting that the disjunct populations do not appear to represent incipient speciation, and should thus be considered under the same taxon.
Various sources have placed O. fraseri in different families including Coerebidae (e.g. Sclater 1986), however, most identify O. fraseri as belonging to Thraupinae or Thraupini (Sibley and Monroe 1990, Dickinson et al. 2003, Clements et al. 2010). Ridgway (1902: 376) was the first to note similarities between Oreomanes and the Conirostrum conebills. This relation has been supported by the discovery of a intergeneric hybrid between O. fraseri and C. ferrugineiventre (Schulenberg 1985), while generic level molecular work has demonstrated that Oreomanes forms a strongly supported monophyletic group with Conirostrum (Burns et al. 2003). Ongoing phylogenetic work has shown that Oreomanes is actually nested within Conirostrum, rendering Conirostrum paraphyletic (K. J. Burns and W. M. Mauck unpublished data).