A Survey On Soil Dematiaceous Hyphomycetes At Species Level From Tibetan Plateau

This study is a part of the project on fungal diversity of dematiaceous Hyphomycetes from soil in China. It aimed at clarifying the diversity at genus and species level, the survival, distribution status and the ecological significance of the soil dematiaceous Hyphomycetes in the Tibeten Plateau as the basis for further studies and utilizations.The 192 soil samples were collected from representative sites selected in Tibet Autonomous Region in 2006-2007. The 456 fungal isolates were got from those soil samples by soil plate methods and dilution plate methods. From which 58 species belonging to 28 genera were identified. Detailed descriptions and illustrations of all the species isolated are given and the locus, altitude and entironment of all soil samples are registered. Latin descriptions are given for the new species.Among them 11 taxa are new species.They are Bipolaris pallescens, Eladia tibetensis, Gliomastix tibetensis, Gliomastix virescens, Humicola tibetensis, Humicola levis, Monodictys tibetensis, Phialophora tibetensis, Scytalidium chinesis, Scytalidium tibetensis, Scytalidium verrucaria.Seven species are new for China: Acremonium furcatum Moreau & R. Moreau ex Gams, Chrysosporium keratinophilum (Frey) Carmichael, Phialophora melinii (Nannf.) Conant, Scopulariopsis fusca Zach, Scopulariopsis hibernica M.Aedine, Scytalidium acidophilum Sigler & Carmichael, Scytalidium circinatum Singler & C. J. K. Wang.One species undeterminated is Periconia sp.Based on comprehensive taxonomic study, the author did a brief discussion on some taxonomic criteria and different taxonomic views, clarified some author's opinion on taxonomy, for example: The fungi of the genus Scytalidium occurred very ofen in the soil, but was regarded its conidia as chlamydospores by some authors before.To clarify its taxonomic position an overall view has been made by the author of this thesis.In this thesis characters of conidiophores, types of conidiogenesis, the stretching patterns of conidiogenous cells, conidium shape and septation were used as main taxonomic criteria at genus level, while the morphology of conidia and conidiophores were the main criteria in differentiating fungal species. Founded on the experiences of the author, colleagues and previous reseachers in the laboratory, a series of applied experimental methods which included isolation, cultural methods, germination test and sporulation stimulating measures etc. on soil dematiaceous Hyphomycetes were summarized. Such as: The probability and quantity of culturing isolates were improved by simulating the nature condition of Tibet and utilizing lixivium of soil medium. Irradiated by near ultraviolet light, drying or freezing in short time, changing pH and injuring purposively can stimulate sporulation of some fungi which are difficult to sporulate in normal condition.