New genus Valtocarpus (Myxomycetes = Eumycetozoa): molecular phylogeny and morphological analysis of aethalioid species in the order Stemonitidales

Phylogenetic position of the taxa in the order Stemonitidales with aethalioid sporophores, Brefeldia, Amaurochaete, and Symphytocarpus, is discussed.The genus Brefeldia is monotypic and is characterized by the presence of multicellular vesicles in the capillitium.Species of the genus Amaurochaete, with the exception of A. trechispora, are distinguished from Symphytocarpus by the presence of a dense cortex, which is preserved after maturation of sporophores.A. trechispora is characterized by complete destruction of the cortex during sporophore maturation.In order to clarify the taxonomic position of this species, a phylogenetic analysis was performed using maximum likelihood method and Bayesian inference based on partial sequences of three unlinked genes.Symphytocarpus trechisporus and A. trechispora form a highly supported monophyletic clade within the family Stemonitidaceae.Both species have purple-brown spore masses and are associated with forests around upland bogs.The other species of the genus Symphytocarpus do not form a well-defined monophyletic group.We propose to assign S. trechisporus and A. trechispora to a new genus Valtocarpus.Our results also demonstrate the non-monophyletic origin of several genera of the families Amaurochaetaceae and Stemonitidaceae and the need for further taxonomic revision of these groups.