Studies On Aulonoraphidinales (Bacillariophyta) Of Freshwater In China

Diatoms are the most species-rich group of algae and the main primary productivity in the marine and fresh water.They are ecologically widespread and have global significance in the carbon and silicon cycles,and are used increasingly in ecological monitoring, paleoecological reconstruction and stratigraphic correlation.Aulonoraphidinales is more evolutional diatom plant,while it is study deficient in our country,only a few areas,in Tibet, Hunan,Heilongjiang et al.,had been relatively systematic investigated.In this thesis,more than 600 samples were observed in the light microscope(LM) and scanning electron microscope(SEM),which collected from 15 provinces where the investigations of algae are relatively deficient,including Hebei,Inner Mongolia,Liaoning, Jilin,Heilongjiang,Shanghai,Jiangsu,Zhejiang,Anhui,Fujian,Hubei,Hunan,Yunnan, Gansu and Xinjiang.On the basis of the currently research situation in China and the results of samples examination,the morphological classification of Aulonoraphidinales from China was studied,according to classification system by Simonsen(1979);The numerical taxonomy of worldwide Epithemiaceae was analyzed by SPSS 13.0;Furthermore,the geographical distribution and ecological characteristics of freshwater Aulonoraphidinales from China were also analyzed.The main results are as follows:1.Based on more than 600 samples,3 families,11 genera,130 species,28 varieties,1 forma were identified,namely Bacillariaceae(5 genera 84 species 7 varieties 1 forma), Epithemiaceae(2 genera 15 species 13 varieties) and Surirellaceae(4 genera 31 species 8 varieties).Moreover,3 species 6 varieties 1 forma were extracted from literatures.Detail characteristics of all species were described,and according to the new characters observed in the LM and SEM,intraspecific and interspecific relationships were discussed.78 plates were presented,concluding 965 photos,775 of which were LM photos,190 were SEM photos.2.One new species was found:Epithemia arguiformis You & Wang;Three drafted new species were described,which all belong to Hantzschia(no nomenclature);New combination of one species,two varieties and one forma were found,Tryb.angustatula(Lange-Bertalot) Q. M.You & Q.X.Wang,Tryb.angustata var.acuta(Grunow) Q.M.You & Q.X.Wang,Sten. curvula var.capitata(Fontell) Q.M.You & Q.X.Wang and Epit.adnata var.proboscidea f. bidens(A.Cleve) Q.M.You & Q.X.Wang;27 species 5 varieties were new records in China, which belong to 3 families 8 genera. 3.The genus Tryblionella was firstly reported in China,it differs from the Nitzschia in which valves are robust,broad,usually undulate,striae usually interrupted by one or more sterna.10 species 1 variety were identified:Tryb.acuminata,Tryb.apiculata,Tryb. angustata,Tryb.angustata var.acuta,Tryb.angustatula,Tryb.calida,Tryb.gracilis,Tryb. hungarica,Tryb.levidensis,Tryb.littoralis and Tryb.victoriae.We support the view of classification of Round et al.(1990):Tryblionella was separated from Nitzschia as a geuns.4.By using software SPSS 13.0,hierarchical cluster analysis of twenty-five morphological characters extracted from twenty-nine species in Epithemiaceae and five outgroup species in Bacillariaceae.The results show that:hierarchical clustering tree can be divided into six branches.It basically agrees with the traditional morphological classification; Denticula and Nitzschia were nested in one group,but not nested with Epithemia and Rhopalodia.It inosculates with classification system of Grunow(1862) and Simonsen(1979). We also adopt this system in our morphological classification.5.Based on identified specimens and literature,the distributions of Aulonoraphidinales in China were discussed.The results show that:(1) Most of the species are cosmopolitan,the distribution in our country has the following three types:â…°.the species are widely distributed, e.g.Nitz.linearis,Nitz.amphibia,Nitz.capitellata,Nitz.frustulum,Nitz.gracilis etc., accounting for around 60%of cosmopolitan species;â…±.the species are sporadicly distributed, which only occur in several provinces,e.g.Nitz.dissipata,Nitz.lorenziana,Tryb.Apiculata etc.,accounting for around 25%of cosmopolitan species;â…².the species are only distributed in one or two provinces,e.g.Nitz.inconspicua,Hant.virgata etc,accounting for around 15% of cosmopolitan species.The results of the latter two situations may be related to lack of resources investigation;(2) there are some regional species,spreading at temperate or subtropical zone;(3) some new species those first found in China,it need for further research to conform whether they are endemic species in China.6.Analysis of ecological characteristics shows that most of Aulonoraphidinales are the benthic and epiphytic types,they are abundant in static water and slow-moving water. Moreover,the ecological distributions of species are affected by the pH and conductivity:the Aulonoraphidinales species are diverse and high biomass in the water with neutral to alkaline pH and medium to high electrolyte.