Published online by Cambridge University Press: 31 May 2012
The ridingsiana group of the genus Euxoa is defined, and the eight constituent species are distinguished by means of a key. Euxoa macrodentata, most closely related to Euxoa cooki McD., is described as new. Euxoa exculta (Sm.) and its nominal subspecies criddlei Sm. are synonymized with Euxoa perpolita (Morr.), and Euxoa perolivalis manitobana McD. is raised to specific rank.