Study and clarification of Peziza petersii and P. proteana (Ascomycota, Pezizaceae), and Underwoodia campbellii resurrected for the “cabbage-head fungus” (formerly P. proteana f. sparassoides)

Amongst the complicated group of Peziza with blue-violet-purplish hymenial surface, P. petersii, P. proteana f. proteana and f. sparassoides were studied using both morphological and molecular approaches (analysis of the nrITS and RPB2 sequences). The nrITS sequences were successfully obtained from the holotypes of Aleuria proteana, P. pseudoviolacea and Underwoodia campbellii. The epitype collection of P. petersii was designated, and its nrITS and RPB2 regions were sequenced. Our analyses showed that (i) P. proteana and P. petersii are a single species, and since P. petersii Berk. was published in 1875 and Aleuria proteana Boud. in 1899, the prioritary name is the former; (ii) P. proteana f. sparassoides (Boud.) Korf, the “cabbage-head fungus”, is a distinct evolutionary line and is here recognised at species level using the oldest available epithet that can be combined in Peziza, Underwoodia campbellii Sacc. Consequently, Peziza campbellii nov. comb. is introduced.