Bombus hortulanus Smith
hortulanus Friese, 1904:188, examined
[hortulans Frison, 1925a:155, incorrect subsequent spelling]

TAXONOMIC STATUS: B. Robustus and B. hortulanus have been considered both as conspecific (e.g. Franklin, 1913; Frison, 1925a) and as separate species (e.g. Milliron, 1973b; Asperen de Boer, 2007).

B. Robustus and B. hortulanus are morphologically similar. Among the specimens I have seen, individuals that have the sides of gastral terga I-II yellow (B. Robustus) also have pubescence extending to the middle or almost to the middle of tergum I, and the males have the space between the inner basal process of the gonostylus and the inner apical process narrower than the apical process. Conversely, individuals with the sides of terga I-II black (B. hortulanus) have at least the middle third of tergum I hairless, and the space between the inner processes of the male gonostylus is wider than the breadth of the apical process.

Until more evidence to the contrary is available from critical studies of patterns of variation, I shall treat them as separate species.

DISTRIBUTION: W Neotropical Region.