Northern Hepatic-tanager (Piranga hepatica) - HBW 16, p. 309

Taxonomy: Pyranga hepatica Swainson, 1827, Temascáltepec, Mexico.
Molecular-genetic evidence indicates that this genus forms a monophyletic group with Habia and Chlorothraupis, and that all three are more closely related to cardinals (Cardinalidae) than to true tanagers. This species, P. lutea and P. flava have traditionally been treated as conspecific, but molecular-genetic analyses suggest that they are better regarded as three separate species, sequence divergence (cytochrome b gene) between individuals from extremes of range (Mexico and Bolivia) being as high as 6·1%; molecular-genetic data indicate that present species and P. lutea are sisters, with P. flava sister to them. Present species and P. lutea are the most similar in appearance, and P. flava and P. lutea differ most in areas where their distributions approach one another; analysis of geographical variation, however, complicated by considerable individual, age and seasonal variation. In the case of present species, wing and tail lengths vary somewhat, size decreasing from N to S (to Nicaragua), but bill length does not. Proposed races zimmeri (described from S Sonora, in NW Mexico) and intensa (from Oaxaca in S Mexico) are both treated as synonymous with nominate. Five subspecies provisionally recognized.