Subspecies Variation- Subspecies' Territorial Ranges
Nominate Form-Subspecies Parellina (Eastern Mexico (from Veracruz, Eastern Puebla and North Oaxaca East to Tabasco, Central Chiapas and Yucatán Peninsula) South to Northwestern Nicaragua.) There is a suspected small breeding population that is believed to have reached Northern Costa Rica through either a natural or an introduced expansion.
Subspecies Beneplacita (Northeast Mexico (Nuevo León and extreme Western Tamaulipas).
Subspecies Indigotica (Western Mexico from Central Sinaloa South on the Pacific slope to Southern Oaxaca and extreme Southwest Chiapas).
Subspecies Variation- Geographic Classification
3 subspecies of Blue Bunting have been recognized by most ornithology groups, (Howell and Webb 1995) the Nominate Form Parrellina and Beneplacita, while not visibly indistinguishable, are sometimes considered the same due to overlapping ranges. (Handbook of the Birds of the World)
Despite cursory similarities between the C.p.beneplacita and C.p.parellina subspecies; there is little to no genetic evidence to support the idea that there is any gene flow between these two subspecies. In the Southern area of Tamaulipas, Mexico; specifically Alta Mira, is the Southern limits of the C.p.beneplacita group. Birds here are not typical C.p.beneplacita, the females however most closely resemble this group and are therefore considered C.p.beneplacita. (Todd, Auk Vo. 40 1923) While there is not yet any evidence to support this, any possible hybridization between these two groups would most likely occur here. Some groups refer to this as a fourth subspecies, C.p.lucida. These individuals are recognized as being brightly colored and small-billed; unlike C.p.beneplacita or C.p.parellina. (Sutton and Burleigh, Auk Vo. 56 1939)
Recent genetic analysis however, seems to reaffirm that there are only three geographically isolated lineages for C.parellina. (R.W. Bryson Jr. Journal of Biogeography Vo. 41 2014) Therefore this is obviously open for more extensive research on the relationships between these subspecies.