Quantitative morphological data on Ramomarthamyces octomerus fungi (Ascomycota)

<p><em>Ramomarthamyces octomerus</em> sp. nov. is described here. This apothecial fungus is described from specimens collected in Mediterranean climate regions in southern Portugal, Spain (Canary Islands), and the Dalmatian region of Croatia. Presumably saprobic, <em>R. octomerus </em>occurs on intact, decorticated wood of <em>Laurus novocanariensis</em> and <em>Olea europaea</em>. 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 <em>Cyclaneusma</em>, <em>Marthamyces</em>, <em>Naemacyclus</em>, and <em>Ramomarthamyces </em>in a core Marthamycetaceae clade that circumscribes primarily leaf-inhabiting, filiform-spored species. In addition, the asci of <em>R. octomerus</em> 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 <em>R. octomerus</em> challenges the characterization of Marthamycetales taxa as possessing inamyloid asci. In our discussion, we provide background and analysis of these notable observations and justify our rationale for retaining <em>R. octomerus </em>in <em>Ramomarthamyces</em> rather than creating a new genus to accommodate it. We also provide notes on the laurel forest habitat of Garajonay National Park on La Gomera island, Canary Islands, Spain, which is a UNESCO World Heritage Site and where the holotype of <em>R. octomerus</em> was collected.</p>