Three New Diatom Species From Coastal Sandy Environment

Three new diatom species,Navicula amoyensis,Hippodonta arenaria,Lunella dalianensis,were described from the sandy environments in Nantaiwu,Fujian Province and Haiyang Island,Liaoning Province,China,using light microscopy and scanning electron microscopy.Lunella genera was firstly recorded in China,and Navicula amoyensis was decribed as a new species which have been published in?Phytotaxa?.Navicula amoyensis is an interesting diatom found in Nantaiwu intertidal flats.The key diagnostic features of this species include the simple terminal raphe endings,broad terminal area,two rows of perpendicular apical pores,a wide contracted girdle region with pectinate margin and internal proximal raphe endings with a raised siliceous rib and accessory rib.Navicula amoyensis is similar with Hippodonta species in most features,but Hippodonta species always lack siliceous ribs from internal proximal raphe endings and pectinate margin in the girdle region.Hippodonta arenaria is another new diatom found in Nantaiwu intertidal flats,Funjian Province.The raphe system is simple in this species and the distal termination of raphe is distinct and slightly curved towards same side.Two rows of areolae positioned in valve apices.Like other Hippodonta species,Hippodonta arenaria doesn't have obvious internal raphe ribs.Lunella dalianensis was found in Haiyang Island in Dalian City,Liaoning Province.It's the first record in China for Lunella genera,and four other species of Lunella have been described from coastal areas and lake.The simplest trait shared by the Lunella species is the catenuloid valve shape,bilaterally asymmetrical in valve view and rectangular in girdle view.The striae,composed of circular to ovoid,rectangular or elongate areolae,are continued on the mantle and around the poles.The girdle bands possess double rows of round poroids.Dorsal margin is convex and ventral margin is slightly convex or sometimes straight.Lunella dalianensis is different from other Lunella species in density of striae,which is distinctly coarser in dorsal than ventral.Especially at the valve center,areolae on the dorsal margin are coarser than on the ventral margin,and almost visible in LM.