Helicocentralis hyalina gen. et sp nov., an aero-aquatic helicosporous fungus (Leotiomycetes, Ascomycota) in Thailand

During a survey of aero-aquatic fungi in Thailand, an undescribed helicosporous fungus was discovered. It is characterized by the presence of branched and septate hyphae with hyaline conidiophores that are micronematous or semi-macronematous, acrogenous and holoblastic. Conidia are hyaline and centrifugally coiled (excentric), helicoid or circinate, coiled 2-3 times clockwise or counterclockwise. After comparison of morphological and molecular characters with other aero-aquatic, helicosporous fungi, introduction of a new genus and species is proposed, Helicocentralis hyalina gen. et sp. nov. Phylogenetic analyses based on the combined sequence data from the small and large nuclear subunit ribosomal DNA (SSU and LSU), as well as internal transcribed spacer (ITS) rDNA sequence data, the fungus groups within the Leotiomycetes class with strong statistical support. The new genus is not related to other helicosporous hyphomycete genera (Helicoma, Helicomyces, Helicoon, and Helicosporium), which belong in the Tubeufiaceae, Dothideomycetes. Within the Leotiomycetes, our new fungus is distantly related to Helicodendron paradoxum (the type species). The new fungus is also compared morphologically to six similar helicosporous genera from Dothideomycetes and Leotiomycetes.