Study On Classification And Community Structure Of Free-living Nematodes In The Intertidal Zone Of The Yellow Sea

From July 2019 to May 2021,samples were collected from the intertidal zone along the coast of the Yellow Sea（31°4′-35°6′N,119°1′-121°6′E）,and undisturbed sediment samples were successfully quantitatively sampled at 8 stations,so as to explore the community structure,classification and diversity of the free-living nematodes.A list of free-living nematodes in the intertidal zone of the Yellow Sea was established,and new species and new recorded species of the sea area were discovered and described.According to the sorting study of sediment samples in the intertidal zone of the Yellow Sea,six groups of meiobenthos were selected,among which the free-living nematodes were dominant,with an average abundance of 1607±579 ind·10cm^-2,accounting for 94%of the total abundance of meiobenthos.The ratio of female to male is1.2:1,and the proportion of juveniles in the nematode community is 44.6%.As to oral cavity types,according to the statistics of nematode species,type 2A has the highest dominance,with 113 species,accounting for 46.7%of the total species;according to the number of nematodes,the number of type 1B nematodes is the largest,accounting for50.7%of the total number.According to the taxonomic study of free-living marine nematodes in the intertidal zone of the Yellow Sea,247 species or taxonomic entities of free-living nematodes were identified,belonging to 104 genera,32 families and 9 orders,among which Daptonema was the most dominant genus,followed by Chromadorina,Ptycholaimellus and Theristus.The most dominant species is Thalassomonhystera Siamensis Kito&Aryuthaka,1998,accounting for 12.6%of the total number of nematodes,followed by Daptonema parabreviseta Huang&Sun,2018 and Ptycholaimellus ocellus Huang&Wang,2011,respectively.In this study,eleven new species of free-living nematodes were identified and described,which are:Setostephanolaimus longiseta Hao,Hu&Huang,2021,Trefusia brevicauda Hao,Chu&Huang,2022,Conilia parasinensis Hao,Chu&Huang,2022,Actinonema diplobulba sp.nov.,Diplolaimelloides rudongensis sp.nov.,Leptolaimus sinicus sp.nov.,Nannolaimoides crassicaudatus sp.nov.,Perspiria zhangi sp.nov.,Setosabatieria longiseta sp.nov.,Theristus unequalis sp.nov.and Tripyloides conicus sp.nov.Six new recorded species of free-living nematodes were identified and described in this study,which are:Enoplolaimus medius Pavljuk,1984,Gammanema uniformis Cobb,1920,Pomponema websteri Sharma&Vincx,1982,Rhynchonema tomakinense Nicholas&Stewart,1995,Thalassomonhystera siamensis Kito&Aryuthaka,1998 and Xyala striata Cobb,1920.In this paper,the classification and community structure of free-living nematodes in the intertidal zone of the Yellow Sea were studied,which improved and enriched the research on the classification and diversity of free-living nematodes in the Yellow Sea.The results provided basic data for the catalogue of marine biodiversity in China,especially the species diversity of free-living nematodes,and laid a scientific foundation for the research on the ecology,diversity and species differentiation of nematodes.