Quantitative morphological data on Ramomarthamyces octomerus fungi (Ascomycota)

Ramomarthamyces octomerus 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, 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 and justify our rationale for
retaining R. octomerus in Ramomarthamyces 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 R. octomerus was
collected.