Six new species of the diatom genus Gomphonema Ehrenberg are described from lakes, swamps, bogs and streams from the Great Xing'an Mountains region of Northeastern China. Descriptions are based on light and scanning electron microscope observations of valve shape, size and ultrastructure. Of the six new species, four are known from the Great Xing'an Mountains only, while two others have been recognized in nearby Mongolia. All six species are known from habitats that are circumneutral to alkaline. Each species is described and compared with similar taxa. These new species descriptions, in addition to the recognition of other new species in the region, suggest aquatic habitats in the Great Xing'an Mountains may support an endemic diatom flora.

Sand-covered rocks provide a particular habitat to benthic seaweeds, which must tolerate the stressful conditions imposed by the presence of sediments. Turf assemblages are dominant in this habitat, which is widely distributed along the Atlantic Iberian Peninsula, neverthelss their flora remained poorly known. This work presents a taxonomic, floristic and chorological account of the most representative Rhodomelaceae from sand-covered rocks along the Atlantic Iberian Peninsula. For each species we provided morphological descriptions, distribution maps, and/or COI-5P sequences, as well as taxonomic notes. The species studied are: Chondria coerulescens, Ctenosiphonia hypnoides, Herposiphonia cf. secunda f. tenella, Leptosiphonia schousboei, Lophosiphonia reptabunda, L. simplicissima sp. nov., Ophidocladus simpliciusculus, Polysiphonia caespitosa, P. devoniensis, P. foetidissima, P. fucoides, P. nigra, P. stricta, P. tripinnata, Pterosiphonia ardreana, P. parasitica, P. pennata and Streblocladia collabens. Among our taxonomical conclusions, we herein proposed a novel species Lophosiphonia simplicissima as well as the transfer of Streblocladia collabens to the genus Neosiphonia: Furthermore, the parasitic species Aiolocolax pulchellus is described and its taxonomic position is discussed.