Morphology and taxonomy of Sinophysis (Dinophyceae, Dinophysiales)including two new marine sand-dwelling species from the North German Wadden Sea

Three sand-dwelling species of the marine dino¯agellate genus Sinophysis were examined from intertidal and subtidal North German Wadden Sea sand and are illustrated by light and scanning electron microscopy. Two are described as new: S. stenosoma sp. nov. and S. grandis sp. nov. Sinophysis stenosoma sp. nov. is compressed laterally with a cell size of 37±56 lm long and 21±33 lm wide, a length}width ratio of 1±43±1±89, an epitheca width (dorsoventrally)of 5±5±8±0 lm, and a sulcus length of about half the cell length. Sinophysis grandis sp. nov. is compressed laterally with a cell size of 50±59 lm long and 35±0±41±5 lm wide, a length}width ratio f 1±29±1±61, an epitheca width (dorsoventrally)of 12±17 lm, and a sulcus length of about three-quarters the cell length. The third species, Sinophysis ebriolum (Herdman)Balech, is the most common species in the Wadden Sea. All species occur throughout the year and are all sand-dwelling, non-photosynthetic, with a smooth theca. They can be distinguished by size, length}width ratio, epitheca size, relative sulcal length and thecal pore pattern. A key to the ®ve known Sinophysis species is provided.