Bombus occidentalis Greene is one of at least three North American bumble bee species within the genus Bombus that is decreasing in abundance and range. Two recent studies used mitochondrial cytochrome oxidase I (COI) barcode sequencing and automated species delimitation methods to identify two evolutionarily unique taxa, B. occidentalisoccidentalis and B. occidentalis mckayi within B. occidentalis, but the species delimitation methods used in the studies disagreed on the species status of B. occidentalis mckayi. We used nuclear (ultraconserved elements) and mitochondrial (COI) markers to infer maximum likelihood (ML) and Bayesian phylogenies of the relationship between B. occidentalis occidentalis and B. occidentalis mckayi. We used seven species delimitation methods to conduct the most thorough test of the species status of these taxa yet performed. The phylogenies from our analyses agree that B. occidentalis mckayi is monophyletic, but our ML phylogenies (UCE and COI) placed that clade within B. occidentalis while our Bayesian phylogeny (COI) resolved the taxa as reciprocally monophyletic. Similarly, the automated species delimitation analyses disagreed between ML and Bayesian phylogenies, with ML analyses lumping the taxa together and Bayesian analyses separating them. Species delimitation analyses based on diversity gaps among sequences, rather than phylogenies, grouped B. occidentalis occidentalis and B. occidentalis mckayi together with their sister species B. terricola. Despite mixed results from species delimitation methods, we believe that the consistent monophyletic assignment of B. occidentalis mckayi specimens represents sufficient evolutionary divergence to elevate B. occidentalis mckayi to the level of species.