Identifications And Phylogeny Of Dorylaimina Pearse,1936

Nematodes are the most widely distributed and abundance multicellular animals on earth,they live in various habitats and are nutritionally diverse,and soil and aquatic nematodes are used as biological indicator in ecological studies.In the soil and freshwater habitat,Dorylaimida(de Man,1876)Pearse,1942 has the largest numbers and diverse,and the suborder Dorylaimina Pearse,1936 includes about 95% species of Dorylaimida.However,studies on Dorylaimida in China are quite deficient.Morphology characteristics and molecular biological characteristics of the dorylaimids extracted from soil samples collected from different habitats in China were analyzed.Phylogeny trees were reconstructed and analysis of phylogenetic relationship were carried out.Keys to,identification characteristics,and taxonomic status of some genera were revised,one new subfamily were proposed.The main results are as follows:1.One new genus,15 new species,one new Chinese record genus,one new Chinese record species and two new record species in Sichuan Province of Dorylaimina were identified.The new species were Labronemella major n.sp.,Calcaridorylaimus tengeri n.sp.,Mesodorylaimus boluoensis n.sp.,Mesodorylaimus major n.sp.,Discolaimus anemaqen n.sp.,Eudorylaimus piceae n.sp.,Discolaimium fragaria n.sp.,Heterodorus qinghaiensis n.sp.,Belondira bagongshanensis n.sp.,Belondira guangzhouensis n.sp.,Axonchium shimentai n.sp.,Tylencholaimus zhongshanensis n.sp.,Tylencholaimus helanensis n.sp.,Dorylaimoides shapotouensis n.sp.and Paratylencholaimus sanshaensis n.gen.n.sp.This is the first record of the genus Aporcella Andrássy,2002 and Mesodorylaimus subtilis(Thorne & Swanger,1936)Andrássy,1959 in China,and Aporcelaimellus obtusicaudatus(Bastian,1865)Altherr,1968 and Xiphinema brevicollum Lordello & Da Costa,1961 in Sichuan Province.The sclerotized pars distalis vaginae of Eudorylaimus piceae n.sp.is a new morphology characteristic.In total,45 sequences of the 18 S rDNA and 40 sequences of D2-D3 region of the 28 S rDNA of 12 new species and 2 known species were obtained.And this is the first report of the rDNA sequences of M.subtilis,Aporcella vitrinus(Thorne & Swanger,1936)álvarez-Ortega,Subbotin & Pe?a-Santiago,2013 and the genus Discolaimium Thorne,1939.2.Results of phylogeny trees based on the 18 S rDNA and D2-D3 region of 28 S rDNA supported the current taxonomic status of the new species.The point that Aporcella and its close genus,Aporcellaimellus Heyns,1965,do not have a close phylogeny relationship was supported by the phylogeny tress based on the 18 S rDNA for the first time.Phylogeny relationships of the families of the superfamily Tylencholaimoidea Filipjev,1934 were discussed based on the cuticle type,female genital system,tail and the number and distribution of male supplements.And it was suggested that the characteristics of Tylencholaimoidea mentioned above may evolve in the following directions or patterns:(a)female genital system of the four families with dorylaimoid cuticle only have one evolutionary direction which is didelphic become opisthodelphic,while the two families with tylencholaimoid cuticle have two evolutionary directions which are didelphic can become opisthodelphic or prodelphic;(b)the tail evolution modes at the species level can be as one is that long tails in both sexes evolved into short tails in both sexes must go through the ?tails dissimilar in sexes‘ stage,the other one is that long tails in both sexes evolved directly into short tails in both sexes without the ?tails dissimilar in sexes‘ stage;(c)the fewer and more widely spaced male supplements is a stable evolutionary characteristic of Tylencholaimellidae Jairajpuri,1964.3.Paratylencholaimus n.gen.and Paratylencholaiminae n.subfam.was proposed based on the analysis of the morphological characteristics of the new genus and the other genus.The taxonomy systems of the family Tylencholaimellidae and Mydonomidae Thorne,1964 were revised based on the characteristics of odontostyle and odontophore.Athernema Ahmad & Jairajpuri,1978 and Agmodorus Thorne,1964 were transferred into Mydonominae Thorne,1964,Mydonomidae.Athernematinae Ahmad & Jairajpuri,1978 of Tylencholaimellidae was canceled.Goferus Jairajpuri & Ahmad,1992,which is the only genera of Dorylliinae Izatullaeva,1967 that odontophore without distinct flag or basal knobs,were contained transferred into Dorylliinae.The main identification characteristics of Dorylliinae were revised as amphid not sclerotized;odontostyle straight and without accessory stiffening piece;odontophore with basal knobs or flag.After revision,Dorylliinae includes the genera Doryllium Cobb,1920,Oostenbrinkella Jairajpuri,1965 and Phellonema Thorne,1964.4.The main identification characteristics of the genus Belondira Thorne,1939 were revised based on the characteristics of odontostyle and anterior part of pharynx of Belondira bagongshanensis n.sp.Keys to the genera Labronemella Andrássy,1985 and Discolaimus Cobb,1913 were revised respectively by adding the morphological characteristics and data of Labronemella major n.sp.and Discolaimus anemaqen n.sp.