Ramomarthamyces octomerus sp. nov. and Insights into the Evolution and Diversification of Ramomarthamyces (Ascomycota, Leotiomycetes, Marthamycetales)

Abstract

The apothecial fungus Ramomarthamyces octomerus sp. nov. is described from specimens collected in Mediterranean climate regions in southern Portugal, Spain (Canary Islands), and the Dalmatian region of Croatia. Presumably saprobic, R. octomerus occurs on intact, decorticated wood of Laurus novocanariensis and Olea europaea. Ascospores are cylindric-ellipsoid and seven-septate. Surprisingly, in our four-locus phylogenetic analysis (nuSSU, ITS1-5.8S-ITS2, LSU, mtSSU), this fungus clusters among species of Cyclaneusma, Marthamyces, Naemacyclus, and Ramomarthamyces in a core Marthamycetaceae clade that circumscribes primarily leaf-inhabiting, filiform-spored species. In addition, the asci of R. octomerus possess an amyloid pore, but the reaction varies between specimens collected in the Canary Islands and those collected in Portugal and Croatia. The occurrence of an amyloid reaction in the asci of R. octomerus challenges the characterization of Marthamycetales taxa as possessing inamyloid asci. In our discussion we provide background and analysis of these notable observations.