Biecheleria donggangensis sp. nov. (Suessiaceae, Dinophyceae), a new marine woloszynskioid species germinated from coastal sediment of the Yellow Sea, China

A new marine woloszynskioid dinoflagellate, Biecheleria donggangensis sp. nov., germinated from the sediments of Rizhao coastal area, China, was examined by light and scanning electron microscopy. Its phylogenetic position was inferred from nuclear rDNA (partial LSU, SSU and ITS1-5.8S-ITS2) sequences. Cells were spherical to ellipsoidal (8.5-19.2 mu m long and 5.9-11.5 mu m wide) with numerous small and discoid chloroplasts, and a centrally located nucleus. Scanning electron microscopy showed an apical furrow area consisting of a single elongated apical vesicle (EAV) with 20 to 34 small globular knobs at the top of the epicone, and 13-15 latitudinal series of amphiesmal vesicles (AVs). Biecheleria donggangensis can be distinguished from other congeneric species by the configuration of the AVs bordering the EAV, the number of latitudinal AVs, and the trichocyst pore (TP) structures around the EAV. Thick-walled and spherical (or oval) cysts were 16.1-23.5 mu m in diameter and decorated with needle-like processes, each with a distal swelling. Molecular phylogenies using maximum likelihood (ML) were examined by three statistical methods (bootstrap, approximate Bayes and the Shimodaira-Hasegawa-like approximate likelihood-ratio test), which clearly demonstrated that the isolate belonged to the genus Biecheleria but formed a clade distinct from all previously described species. Genetic distance analyses justified describing the isolate as a new species rather than a new ribotype of B. cincta.