Two subspecies usually are recognized:
nominate melanogaster:, described as Rhamphopis melanogaster Swainson 1838; type locality Peru, restricted to Moyobamba, San Martín, Peru, by Zimmmer 1929c: 97
Occurs in the Mayo Valley and south along the Río Huallaga at least to ca 7º S (Zimmer 1929c, 1945a).
See Detailed Description.
transitus, described as Ramphocelus melanogaster transitus Zimmer 1929; type locality Chinchao, Huáuco, Peru.
Occurs in the upper Huallaga Valley, central Peru, north at least to ca 8º S (Zimmer 1929c, 1945a).
Similar to melanogaster, but in the male the throat and breast are paler, and less sharply contrasting with the red of the lower breast and flanks; and center of the back is more suffused with red (Zimmer 1929c, 1945a).
Ramphocelus melanogaster is in the tanager family Thraupidae and belongs to the subfamily Tachyphoninae (Burns et al. 2014). This subfamily, also known as the "ornamented tanagers", includes many species distributed across the Neotropical lowlands, and most species have social ornaments such as crests or bright color patches (Burns et al. 2014). There are 10 genera (including Ramphocelus) in this subfamily. The genus Ramphocelus includes nine species and is most closely related to a clade containing three Tachyphonus species (Red-shouldered Tanager T. phoenicius, Ruby-crowned Tanager T. coronatus, and White-lined Tanager T. rufus; Burns and Racicot 2009, Burns et al. 2014). Zimmer (1929c) and Ridgely and Tudor (1989) suggested that Ramphocelus melanogaster could be conspecific with Crimson-backed Tanager R. dimidiatus and Silver-beaked Tanager R. carbo, and Storer (1970) considered these three species, together with Brazilian Tanager R. bresilius, to form a superspecies. This group of species do not form a monophyletic group, however, unless Masked Crimson Tanager R. nigrogularis also is included (Burns and Racicot 2009, Burns et al. 2014). According to molecular phylogenies (Burns and Racicot 2009, Burns et al. 2014), the Black-bellied Tanager’s closest relative is Silver-beaked Tanager. The two species have visual and vocal similarities and show a low level of sequence divergence (1.1%) relative to other interspecific comparisons of Ramphocelus species (Burns and Racicot 2009). A few specimens have been reported with characteristics intermediate between melanogaster and carbo (Hellmayr 1936: 261, Zimmer 1945a), suggesting some level of hybridization between these species.