Identity of the plasmodial slime mold Phytoceratiomyxa osmundae and the lectotypification of Taphrina osmundae, the basionym of Mixia osmundae

Phytoceratiomyxa osmundae, parasitic on fronds of Osmunda japonica var. sublancea in Taiwan, was described as a new genus and species in the Myxomycetes by Sawada in 1929. Our investigations on the type specimen, and related descriptions and illustrations of P. osmundae, revealed that this microorganism, originally identified as a myxomycete, was phenotypically identical with Mixia osmundae, which was transferred from the Ascomycota to the Basidiomycota based on the integrated analysis of molecules and morphology by Nishida et al. in 1995. In addition, a lectotype for Taphrina osmundae, the basionym of Mixia osmundae, is also designated. A nomenclatural proposal regarding the generic names Phytoceratiomyxa and Mixia related to this study will be published elsewhere.