Distribution and ecology. This saxicolous species is known only from Japan and the Bering Straits.
Remarks. Fuscidea circumflexa is characterized by the presence of alectorialic acid in the thallus and apothecia. This substance causes the thallus to react Pd+ yellow, KC+ red, UV+ orange. Fuscidea circumflexa (Nyl.) V. Wirth & Vezda, described from the Asian side of the Bering Straits, is very similar to F. scrupulosa and may be conspecific with it, as it apparently differs only in having a thicker, verrucose thallus (Fig. 15). The lectotype of F. circumflexa (not holotype as stated by Inoue 1981a) is extremely poor, being less than 1 cm2 and having only two apothecia (both of which have been sectioned by previous investigators). An isotype in S is larger, although still small, and has several apothecia, but it is impossible to be certain that the two species are not conspecific. Consequently, given that the two taxa are allopatric and appear to differ in gross morphology, I here retain them as separate species. Inoue (1981a) reported F. circumflexa from Japan but from his description ‘‘areoles plane or slightly convex’’ and his illustration, it appears his specimens may represent F. scrupulosa.