Classification Of The Free Living Nematodes In Tong'an Bay Mangrove Wetland,Fujian

Free-living marine nematodes represents the most widely distributed,the most abundant and the highest diversity of metazoan groups.As the main groups of meiofauna,they play an important role in the food web of sedimentary environment.With the further study of marine nematodes response for specific environment(such as acidification,sea level rising,global warming,hypoxia environment and organic pollutants),taxonomy and ecology of marine nematodes are increasingly brought to the attention of the international academic circles.Although the taxonomy of free-living marine nematodes began in the 1980s in China,because of the less researchers,marine nematodes formed a specific morphological and ecological adaptation in different types of sediments,research on the taxonomy of marine nematodes is still in its infancy,a large number of nematodes is still unknown and needs to be found.The vast majority of free-living marine nematodes from artificial mangrove wetland in Tong'an Bay were only identified to genus level,the study identified some dominant genus to species to provide new species for mangrove wetland biodiversity research,to provide a scientific basis for artificial mangrove wetland management and ecological restoration.Thirteen nematode species were described and illustrated in detail,including six new species and three new geographical record.The morphological features are as follows:Tripyloides caudaensis is characterized by a 16.5-22.7,smooth outer labial and cephalic setae,7.2-8.8 ?m and 3.5-5.8 ?m long,respectively,relative small amphideal fovea(17-19%c.b.d.),distinctly set-off proximal conical and distal cylindrical tail;c 8.8-11.0,c' 2.8-3.6,spicules 41.6 ?m long,neither mid-ventral preanal nor postanal supplementary papillae present.Tripyloides gracilis is characterized by a 19.1-24.1,outer labial and cephalic setae,6.2-8,9 ?m and 4.2-6.8 ?m long,respectively;amphideal fovea 15-21%c.b.d.wide,situated at level of posterior lateral pouches of stegostoma;buccal with two divisions,with a small tooth in the anterior portion;spicules 38.9 ?m long,shorter than gubernaculum.The tail is conical-cylindrical,the last 1/3 is cylindrical;c 11.0-12.7,c'2.6-3.3.Dorylaimopsis huojuensis sp.nov.is characterised by cuticle with lateral differentiation consisting of five or six longitudinal rows of larger dots in pharyngeal and caudal regions,two rows of larger dots in middle region of body,cephalic setae 6-8 ?m long,amphideal fovea with 3.0 turns,and spicules 113.7-123.2 ?m long without ventral projection;15 pre-cloacal supplements.Halichoanolaimus xiamenensis sp.nov.is characterized by cuticle with transverse rows of lateral dots;amphid with 3.5 turns,29%of head diameter,situated near mid-length of buccal cavity;about ten denticles in a set at the border of anterior and posterior parts of the buccal cavity,each set subdivided into two parts by a tooth like structure;spicules arcuate,1.8 anal diameter,gubernaculum with apophyses;tail consisting of anterior conoid(12%)and posterior cylindrical(88%)parts;two conical mid-ventral precloacal papillae.Cobbionema xiamenensis sp.nov.is characterized by about twenty five denticles in two rows in the buccal cavity;amphid with 3.5 turns,48%of head diameter;spicules 90 ?m(1.6 a.b.d.),with a distinctive ventral swelling near the distal tip;simple gubernaculum 35 ?m long;tail consisting of anterior conoid(40%)and posterior cylindrical(60%)parts.two precloacal papillae.Metachromadora(Metachromadoroides)xiamenensis sp.nov.is characterized by finely annulated cuticle;deep longitudinal ridges start at mid pharynx level and reach middle of tail;amphidial foveae loop shaped,open top,and have double contour;53-66%c.b.d.wide;pharynx with bipartite cuticularized internal cavity,bulb length is 33-34%of the total pharynx length;spicules 46-56 ?m,with well developed head;18 supplemental organs;tail short,conical,its terminal end ventrally curved.Molgolaimus euryformis sp.nov.is characterized by a short body(485.6-620.7?m);a wide head diameter(12.4-14.5 ?m);relative small amphidial fovea(5-6 ?m in diameter);a spherical oesophageal bulb;the short ventrally curved spicules(29-32?m),0.6-0.8 anal body diameter long;gubernaculum with a distal hook;a conical-cylindrical tail with swollen tip and absence of pre-cloacal supplements.Promonhystera filicaudata sp.nov.is characterized by striated cuticle,very long(about one-third of head diameter)labial papillae setose,10 cephalic setae and somatic setae;amphids circular,18-20%c.b.d.wide,8.7-10.24 ?m from anterior end;elongate spicula,88.5-92.9 ?m;gubernaculum a small plate with a distal hook;conical-cylindrical tail,5.3-6.1 anal diameter.Eleutherolaimus euryformis sp.nov.is characterized by cephalic setae arranged in two separate circles at the level of the anterior gymnostom margin,anterior cephalic circle consisting of four setae,3.3-5.5 ?m,posterior cephalic circle consists of four or six setae,4.2-6.0 ?m,four cervical setae behind base of stoma;sclerotized stoma,with parallel walls,anterior rhabdions set off by ring;circle amphids situated opposite mid-stoma,about 33-39%of corresponding head diameter;spicules arcuate,distally acute,39.0-43.9 ?m;gubernaculum with triangular posterior apophysis;tail elongate,conical,with rounded tip.