An emended description of the genus Fogedia (Bacillariophyceae) with reports of four species new to science from a Korean sand flat

A taxonomic investigation of the microphytobenthos from the lower intertidal zone of a Korean sandflat revealed unprecedented dominance and diversity of the marine diatom genus Fogedia. Four new species are described: Fogedia coreana sp. nov., F. densa sp. nov., F. elliptica sp. nov., and F. lyra sp. nov. A great abundance of Fogedia species in the study area provided a unique opportunity to observe the frustule ultrastructure and cell contents. The first reported observation of the presence of two girdle-appressed plastids each with a single rod-like pyrenoid was made in species of Fogedia, indicating its close relationship to Navicula sensu stricto and Hippodonta. Ultrastructural characteristics ( e. g. hymenate areola occlusions) of Fogedia also support such a relationship. Meanwhile the genus Fogedia differs from Navicula sensu stricto with respect to the raphe system and differs from Hippodonta with respect to the girdle bands and apical striae. The present study increased the overall worldwide number of the taxa of Fogedia to 13. An emended generic description of Fogedia is provided along with the biogeographic information of the species belonging to the genus.