Camponotus species present in Canada are distributed in the sub-genera Camponotus, Myrmentoma and Tanaemyrmex (Mackay 2019). Camponotus discolor is a member of the sub-genus Myrmentoma. There are three other species of this sub-genus with official records from Canada; C. nearcticus Emery, C. subbarbatus Emery, and C. caryae Fitch (Janicki et al. 2016). Two other species may be present but need validation; C. near hyatti Emery in British Columbia (Higgins and Lindgren 2009) and one museum record of Camponotus sayi Emery in southern Ontario without mention in the literature (Janicki et al. 2016).

Species of the Myrmentoma subgenus can be distinguished from other Camponotus by the presence of a distinct semicircular median notch or emargination in the middle of the apical margin of the clypeus. This notch is most visible on minor and intermediate workers and is often reduced to a barely noticeable medial depression on the clypeus of the largest major workers (Ellison et al. 2012; MacGown et al. 2007; Snelling 1988). Members of this subgenus are also considerably smaller, the total length of minor workers being less than 7mm, less than 9mm for the major workers, and less than 10mm for queens (Mackay 2019).

Camponotus discolor is morphologically closest to C. caryae. They can be distinguished by the variation in length of erect hairs on the clypeus. In C. caryae, the length of the clypeal erect hairs is variable, displaying a “gradation” from shorter to longer hairs. The shortest hairs are similar or equivalent in length to those of the malar region. In comparison, the clypeal erect hairs of C. discolor have two distinct lengths: long and short, and the short hairs are shorter in length than those of the malar region (Snelling 1988). Body coloration is usually darker in C. caryae, displaying variations from dark brown to black, while C. discolor typically exhibits a redder coloration on all body parts, except for the gaster, which is blackish (MacGown et al. 2007). Finally, both species have different habitat preferences. In the United States, C. discolor is commonly associated with oaks but can also be found on other trees, such as hickories (Carya spp.), willows (Salix spp.), and cottonwood (Populus spp.) (Snelling 1988; MacGown et al. 2007). In comparison, C. caryae is usually associated only with hickory trees (Snelling 1988). Because the criteria that separate the two species are often deemed unsatisfactory, the primary criterion for differentiation is frequently based on color. For this reason, C. discolor has been treated as a subspecies of C. caryae by different authors (Creighton 1950; Wheeler & Wheeler 1963). However, Snelling (1988) considers these criteria valid. Since 1988, C. discolor has been recognized as a distinct species, as no specimens with intermediate criteria have ever been collected. As the two species are rarely collected, comparing populations becomes challenging. Therefore, molecular analysis may be necessary to determine the status of several species of the sub-genus Myrmentoma.