Hypogymnia incurvoides Rass. was originally described from the Archangel'sk Region in northwestern Russia in 1967. Long neglected, it has since been found at several sites in Newfoundland and Nova Scotia in eastern Canada. Hypogymnia incurvoides is most similar to H. physodes, but is readily distinguished from that species by the presence of holes in the lobe tips and axils, black-margined lobes forming a regular lattice, and the absence of 3-hydroxyphysodic acid. This substance gives a K reddish brown reaction, which is consistently seen in H. physodes but not H. incurvoides. The species should be sought in other oceanic boreal to subarctic locations in the Northern Hemisphere.