Ciassification, Identification And Molecular Phylogenetics Of The Family Chaetomiaceae

The family Chaetomiaceae was reported as a saprophyte, destroying substances containing cellulose. In this thesis, the author discussed the range of the family and the present situation on the taxonomy of the genera relied on practical work. Morphology of ascomata, ascospore, and presence of ascomatal hairs and character of anamorph was used to delimite the genera. The characteristics of ascospore, such as size, shape, symmetry, structure, pigmentation, presence, position and number of germ pores are the most important classified criteria of species. The size, shape of ascomata and ascus are useful to identify species. The ascomatal hairs have been seen important taxonomic standards; however, they usually neglected because they varied as time and the environmental change. Although a few species produce anamorph, the structures of anamorph were notably differential among them, the morphology of anamorph should consider as one of the criteria. Growth rate, pigmentation and exudates of colonies are with some extend value for delimitation species. Test indicated it was easy to isolate species of Chaetomiaceae on Martin medium after dealing by 60% alcohol for 7-10 min.. Biological characteristics of Chaetomiaceae were valuable to identify species. However, they were variable. Therefore, we studied the culture conditions on the effect of biological characteristics. Growth of colonies are related to the production of ascomata, that is, the better colonies grew,the more ascomata produced. Some species are thermotolerant, they grew well at 40-45℃. The species which were similar in morphology could be distinguished by the range of growth temperature. Compared the colonies on yeast powder agar(YPA), cornmeal agar(CMA), oat agar(OA), potato dextrose agar(PDA), malt extract agar(MEA) and tap water agar(TWA), most of the species need abundant nutrient during the growth period but without selection of nutrient. It could accelerate the production of ascomata and shorten the maturing time when cellulose added, without conspicuous affect on the structures of ascospores. The species of Chaetomium, Thielavia and Corynascus which were difficult to be identified through morphological were analyzed by the internal transcriber spacer (ITS) of ribosomal. The analysis of ITS indicated the sequences have a little difference in different genus, but have little difference among species in the same genus. Phylogenetic analysis of nucleotide sequences conducted was using maximum parsimony methods. Topologies of most parsimonious and neighbor-joining tree clearly displaied the genera in a defined clade, supported by a bootstrap value of 100%, but supported by low bootsrap value aomg species in the same genus. ITS sequences were useful to establish phylogenetical relationships, but not useful to identify these species. On the basis of morphological characters, 1274 specimen from Shaanxi Province, Sichuan Province, Chongqing city, Hubei Province, Hunan Province, Jiangxi Province, Anhui Province, Zhejiang Province, Jiangsu Province and Shanghai city were isolated and identified, including plant debris 947, soil 297, dung 30. 3 genera and 26 species described , including 1 species novel: Corynascus nanjingnensis sp. nov., 1 new record genus: Corynascus, 12 new records species: Chaetomium cruentum, Ch. cymbiforme, Ch. globosporum, Ch. hexagonosporum, Ch. homopilatum, Ch. madrasense, Ch. quadrangulatum, Ch. spinosum, Ch. subaffine, Ch. virescens; Thielavia microspora and Th. Terricola.