Classification Of Freshwater Dothideomycetes And Anamorphic Fungi In Northern Thailand

Freshwater fungi were defined as "fungi that the whole or part of their life cycle rely on freshwater". Freshwater fungi can decompose organic substrata in freshwater, and their mycelium are involved into the food web when grazed by animals. As a rarely exploited bio-resource, freshwater fungi have great potential in producing various and useful metabolites.Taxonomic and systematic studies are foundation and essential to the research and application of freshwater fungi. Fungi were estimated globally with about5million species, of which only100,000species were known. Most researchers have concentrated on terrestrial fungi and only about1,200species were discovered from freshwater habitats. Numerous species new to science are supposed to be encountered in the future study especially the most poorly reported areas, such as tropical area, and less investigated habitats, such as freshwater habitats. Freshwater fungi have been classified according to morphological characters for a long time with few taxa studied with molecular method. In this study, we aim to investigate new taxa and new records of freshwater fungi, connect teleomorph and anamorph, incorporate anamorphic fungi to ascomycete taxonomic framework and establish classification system for freshwater Dothideomycetes and anamorphic fungi.The freshwater fungi were collected and investigated in Northern Thailand (Chiang Rai and Chiang Mai provinces). Totally538submerged woody samples were collected from various freshwater habitats including streams, lakes and ditches. The fungi on submerged wood were identified and isolated, and18S,28S and ITS sequences were analyzed to study the systematics. In whole89species out of65genera were identified.258herbaria were deposited in MFLU herbarium. Wholly101pure cultures were got and deposited in MFLUCC. Ninety sequences were got. Seventeen sequences were uploaded to GenBank. Based on morphology and molecular study, two new species Helicascus aegyptiacus and Helicascus aquaticus, and two combined new species Helicascus elaterascus and Helicascus thalassioideus were introduced. It exposed a new habitat (freshwater) for Helicascus. Helicascus aquaticus produced "Pleurophomopsis"-like asexual state through the method of sterilized pine needles abduction. This is the first report of asexual state for Helicascus. Meanwhile, Phylogenetic analyses of Pleosporales were conducted based on LSU and SSU sequence. Three anamorphic taxa Acrocalymma aquatic, Aquasubmersa mircensis and Clohesyomyces aquaticus were located to ascomycete taxonomic framework according to the molecular studies. Acrocalymma aquatic and Aquasubmersa mircensis are new species and both in a distinct lineage of Pleosporales. Clohesyomyces aquaticus were firstly facilitated its accommodation in Lindgomycetaceae, Pleosporales. This makes a step forward in the studies of teleomorph-anamorph connection.All reported freshwater species within Dothideomycetes were integrated and the classification system of freshwater Dothideomycetes was achieved through multilocus phylogenetic study including81species in26genera. There are one species respectively in Lucidascocarpa, Dothideaceae, Dothideales, Dothideomycetidae; four species in Mycosphaerella, Mycosphaerellaceae, Capnodiales, Dothideomycetidae;71species in14families of Pleosporales, Pleosporomycetidae; and five species which positions are uncertain. The morphological characters of each genus were discussed. Keys to species in the families were provided. One new species was described and named as Lophiostoma papilliovagina. It belongs to Lophiostomaceae, Pleosporales, Pleosporomycetidae. Meanwhile, the morphological characters and keys to species of65species in12common freshwater hyphomycetes genera were compared and constructed in this paper, including Acrogenospora, Brachysporiella. Canalisporium, Dictylaria, Dictyosporium, Digitodesmium, Ellisembia, Helicomyces, Helicosporium. Monotosporella. Phaeoisaria. Sporosthisma. The classification system constructed in this study is essential for future study on freshwater fungi.A new coelomycetes genus Aquasubmersa was erected. Six new species and two new combinations were described based on morphological and molecular data including three ascomycetes:Helicascus aegyptiacus, Helicascus aquaticus and Lophiostoma papilliovagina; two coelomycetes:Acrocalymma aquatic and Aquasubmersa mircensis; one hyphomycetes:Dactylaria thailandensis; and two new combinations, namely Helicascus elaterascus and Helicascus thalassioideus. The morphological differences between close related species were discussed. Herbarium of type species were deposited in Mae Fah Luang University, Thailand (MFLU). Seven species were first reported from Thai freshwater habitats, including Astrosphaeriella africana, Digitodesmium heptasporum, Ellisembia vaginata, Helicosporium panacheum, Fissuroma aggregata, Jahnula sangamonensis and Sporoschisma saccardoi.