Taxonomic and nomenclatural notes on sooty mould names based on species mixtures: Hormiscium handelii and Torula lechleriana

Sooty moulds often grow in colonies of more than one species, and taxonomic descriptions thus often unknowingly combine elements of different fungi. The species composition of such mixtures can be clarified by microscopic examination of undisturbed colonies removed from the substrate using the collodion technique. This method facilitates analysis of hyphal morphologies and the associations of different synanamorphs with these hyphae, i.e., the recognition of character suites that correlate with sooty mould families. Earlier versions of the International Code of Botanical Nomenclature allowed a name based on a mixture to be designated a nomen confusum, but since 1978 the Code has required selection of one species or one morph to serve as the lectotype for the name. Two binomials are revised here, with the component parts of their holotypes characterized and compared with their protologues. The type specimen of Hormiscium handelii is dominated by monilioid hyphae of a member of the Metacapnodiaceae with a hyphomycetous Capnophialophora anamorph; this latter morph is selected as the lectotype. No new combination is made because no spores were observed, so that it is impossible to adequately characterize the fungal species represented by this morph. The type of Torula lechleriana comprises three species, but it is dominated by the characteristic monilioid hyphae of a member of the Metacapnodiaceae, with Capnobotrys conidiogenous cells and conidia. The latter anamorphic fungus is chosen as the lectotype, and a taxonomic description is provided for the resulting new combination, Capnobotrys lechleriana.