Systematics

Two subspecies of S. ramphastinus are recognized:

caucae (Gyldenstope, 1941) in the northernmost part of its distribution, in western Colombia from Valle to Nariño.

"Barely differs from the nominate ... in having less olive and more grey and sooty in the outer web of the inner primaries and secondaries; also averages slightly more extensive red on the breast and belly ([although] some nominate birds are as red)" (Short and Horne 2001).

ramphastinus (Jardine, 1855) in the southernmost part of its distribution, in northwestern and central western Ecuador

The traditional classification of Semnornis ramphastinus in the family Capitonidae was challenged as the paraphyly of the Capitonidae has been documented through phylogenetic analyses of morphological data (Prum 1988), DNA hybridization data (Sibley and Ahlquist 1990), and phylogenetic analysis of DNA sequence data (Barker and Lanyon 2000, Moyle 2004). It is generally accepted that Semnornis is the most closely related to toucans than other Neotropical barbets (e.g., Prum 1988, Patel et al. 2011), although the placement of Semnornis as basal to the other Neotropical barbets (which would signify that all Neotropical barbets are monophyletic) or toucans is still unresolved. Consequently the family Semnornithidae is recognized for Semnornis until the phylogenetic relationships between Semnornis, other New World barbets, and toucans are clarified (Remsen et al. 2013). Additionally, African barbets (Lybiidae) are more closely related to Neotropical Barbets and toucans than are Asian barbets (Megalaimidae) (Moyle 2004).