Reassessment of Dyfrolomyces and Four New Species of Melomastia from Olive (Olea europaea) in Sichuan Province, China

Pleurotremataceae species are saprobes on decaying wood in terrestrial, mangrove, and freshwater habitats. The generic boundary of the family has traditionally been based on morphology. All genera of Pleurotremataceae have a high degree of morphological overlap, of which the generic circumscription of Melomastia and Dyfrolomyces has not been well resolved. Thus, the delimitation of genera has always been challenging. Melomastia traditionally differs from Dyfrolomyces in having 2-septate, oblong, with obtuse-ends ascospores. These main characteristics have been used to distinguish Melomastia from Dyfrolomyces for a long time. However, the above characteristics sometimes overlap among Dyfrolomyces and Melomastia species. Based on the morphology and multigene phylogeny with newly obtained data, we synonymized Dyfrolomyces under Melomastia following up-to-date results. Four novel species (i.e., Melomastia fusispora, M. oleae, M. sichuanensis and M. winteri) collected from the dead branches of Olea europaea L. in Chengdu Olive Base, Sichuan Province in China are introduced based on detailed morphological characterization and phylogenetic analyses of sequences based on nuclear ribosomal (LSU and SSU) and protein-coding gene (tef1-α). The 11 new combinations proposed are Melomastia aquatica (=Dyfrolomyces aquaticus), M. chromolaenae (=D. chromolaenae), M. distoseptata (=D. distoseptatus), M. mangrovei (=D. mangrovei), M. marinospora (=D. marinosporus), M. neothailandica (=D. neothailandicus), M. phetchaburiensis (=D. phetchaburiensis), M. sinensis (=D. sinensis), M. thailandica (=D. thailandica), M. thamplaensis (=D. thamplaensis) and M. tiomanensis (=D. tiomanensis).