Revision Of Doubtful Marcrobenthic Species And The Preliminary Study Of Formation Mechanism Of Estuarine Species In The Yangtze Estuary

Macrobenthic invertebrates at the Yangtze River estuary play a vital part in the local ecological system.Scientific research can be further performed on community structure,physiological mechanism and environmental toxicological effect of related species based on correct identification and classification of macrobenthic invertebrates at the Yangtze River estuary.Meanwhile,from the perspective of biogeography,correct identification of affinis species distributed by salinity gradient change of fresh water,estuary,and ocean can offer better research on their distribution and habitats.Only through establishing phylogenetic relationship and estimating divergence time of sibling species based on the former research can the further research on the reason of biodiversity be conducted.In this study,macrobenthic invertebrates specimen collected in specimen museum of Yangtze River Delta Estuary Wetland Station and some supplementary specimen are classified by traditional morphological classification.Additionally,some doubtful species are reidentified by DNA barcoding technology.In the classification based on traditional morphological characteristics,some doubtful species are redescribed and their morphologies areidentified by comparing important classification feature of specimen at the Yangtze River estuary and specimen of affinis species or affinis species in documents.Mitochondrial COI gene,mitochondrial 16sRNA gene,nuclear 18sRNA gene and 28sRNA gene are utilized during DNA molecular sequencing to conduct molecular phylogeny,offering support to the revision of doubtful species at molecular level.Two major advances were made in this paper:1.Some doubtful species of macrobenthic invertebrates at the Yangtze River estuary are clarified and the amendment results are as follows:Dentinephtys glabra(Hartman,1950)is actually Nephtys glabra(Hartman,1950);Corbicula fluminea(O.F.Muller,1774)is Corbicula largillierti(Philippi,1844)indeed;Corophium volutator(Pallas,1766)turns out to be Sinocorophium dongtanense(Ren&Liu,2014);Synidotea laevidorsalis(Miers,1881)is Synidotea laticauda(Benedict,1897)in fact;Gnorimosphaeroma rayi(Hoestlandt,1969)is actually Gnorimosphaeroma chinensis(Tattersall,1921);Chiromantes dehaani(H.Milne-Edwards,1853)is Chiromantes neglectum(De Man,1887);additionally,Ilyoplax deschampsi(Rathbun,1913)comes from intraspecific variation,hence the hypothesis of cryptic species fails.2.Regarding the fact that some macrobenthic invertebratesat the Yangtze River estuary are distributed in estuary area,the concept of estuarine species is proposed,including Nephtys glabra(Hartman,1950),Corbicula largillierti(Philippi,1844),Sinocorophium dongtanense(Ren&Liu,2014),Gnorimosphaeroma chinensis(Tattersall,1921),Cleantioides emarginata(Kwon&Kim,1992),Chongxidotea annandalei(Tattersall,1921),Synidotea laticauda(Benedict,1897),Exopalaemon annandalei(Kemp,1917),Exopalaemon carinicauda(Holthuis,1950),Palaemon gravieri(Yu,1930),Chiromantes neglectum(De Man,1887),and Ilyoplax deschampsi(Rathbun,1913).Through Bayes method,divergence of estuarine species is estimated,and occurrence time of natural geological events is compared to explain the formation mechanism of estuarine species by reasons like transgression,regression,and bioretention.The revision of doubtful species of macrobenthic invertebrates at the Yangtze River estuary is to continue the massive accumulation and constant replenish of specimen in Yangtze estuary,and also a fundamental work conducted under the attention on researches on the classification and identification of relevant species.The completion of this work will help discover the overlooked science research and advance the process of relevant subjects,also,it has certain practical significance towards people's production and living.In this research,DNA molecular sequencing is used to estimate divergence time of estuarine species and sibling marine species,then the formation mechanism of estuarine species is explained.This is an attempt to explain the reason of biodiversity of macrobenthic invertebrates at the Yangtze River estuary,and it is a positive example for the future research on biodiversity.