The Diversity Of Freshwater Fungi Along Lancang-Mekong River, With The Identification Of Seventeen New Species

In recent years,freshwater fungi have been mostly reported in tropical regions.The Lancang-Mekong River is one of the most biologically diverse areas in the world with all climate types.The entire basin has complex topography and abundant water resources,which provides suitable conditions for the growth and reproduction of various fungi.Worldwide scholars have carried out research on freshwater fungi in the Lancang-Mekong River,and a large number of species have been reported,and a series of useful results have been made,which has deepened people's understanding of the freshwater fungi resources in the Lancang-Mekong River.However,the molecular data and morphological description of many species haven‘t been comprehensively studied.In view of this,we aimed at studying the fungal diversity and reporting new species,and using modern molecular systematics to establish a fungal phylogenetic tree to achieve the full use of freshwater fungal resources,and obtain pure cultures of species and do molecular experiments,then enrich the database of Genbank.In this thesis,samples were collected from Chiang Mai and Chiang Rai(Thailand),De Hong and Hong He(China).Among of those,totally 200 fresh specimens were collected,360 sequences were obtained,88 strains were identified,80 pure cultures and 88 dry specimens were deposited in Mae Fae Luang University(MFLU)and Mae Fae Luang University Culture Collection(MFLUCC),Kunming Institute of Botany,Academia Sinica(HKAS)and Kunming Institute of Botany Culture Collection(KUMCC).The first second chapters of this thesis are mainly on the background,significance,materials and methods.The third chapter is mainly talking about the fungi diversity.The analysis showed that the species were distributed in 3 classes,mainly including Sordariomycetes,Dothideomycetes,and Eurotiomycetes;15 orders,mainly containing Annulatascales,Chaetosphaeriales,Pleosporales,Xylariales,Hypocreales,and Togniniales;28 families,mainly comprising Annulatascaceae,Chaetosphaeriaceae,Nectriacea,Distoseptisporaceae,Atractosporaceae,and Herpotrichiellaceae;40 genera,mainly consisting of Annulatascus,Fluminicola,Thysanore,Diatrypella,Chloridium,and Dictyosporella;88 species,including 37 new species,31 known species,and 20 species to be identifie.To understand the distribution and the abundance of these species,we have established a table for class,order,family,genus and species.We mainly analyed four new species,including one new genus Proliferophorum(Diaporthomycetidae,genera incertae sedis)from Chiang Rai;one new species Mariannaea chiangraiensis(Nectriaceae)from Chiang Rai and Yunnan;one new species Minimelanolocus nonramosus(Herpotrichiellaceae)from Ching Mai;and one new combined species Thysanorea papuan(Herpotrichiellaceae)from Ching Rai.The new genus Proliferophorum was established to accommodate a new species Proliferophorum thailanddium(holotype);and it was introduced to accommodate the Dothideomycetidae species forming percurrently 1–2 times at broken ends conidiogenous cells.The new species Mariannaea chiangraiensis was introduced as no conidial chain in the genus Mariannaea,and its size and shape of the conidia were different from other species of Mariannaea.The new species Minimelanolocus nonramosus was introduced as a species of unbranched conidiophores in the Minimelanolocus.Thysanorea papuan was introduced as a new combined species,it was re-examined and analyzed,then we found that its conidiophore character ?branched head sometimes or often breaks off from the stipe and with a percurrent proliferation? was easily observed in all the collections of Th.papuana.This character is an important morphological marker in Thysanorea at the genus level and which is of morphological significance to distinguish this genus from other related hyphomycetous taxa.Based on morphological and molecular data,the Chapter Four builded a phylogenetic tree of part Annulatasaceae-like species by LSU,SSU,ITS and TEF sequence data.In this section,21 strains were described and identified,including 9 strains of freshwater ascomycetes and 13 strains of freshwater hyphomycetes.Among them,there were 13 new species,containing Dictyosporella aquaticum,D.dehongensis(Diaporthomycetidae,genera incertae sedis);Conlarium chiangraiensis,C.dehongensis,C.aseptata(Conlariaceae);Fluminicola satunensis,F.chiangraiensis(Papulosaceae);Atractospora saprotrophica,A.aquatica(Atractosporaceae);Diluviicola saprotrophica(Pseudoproboscisporaceae);Annulatascus aquatica(Annulatascaceae);Distoseptispora thailandensis,D.yunnanensis(Distoseptisporaceae).According to previous findings,the characters of Annulatasaceae-like species were similar,therefore,the taxonomic status was prone to confusion.Hence,we need to continuously supplement and improve molecular data,and provide more comprehensive and accurate form information.This study provides a theoretical basis for further rational development and utilization of freshwater fungi resources.