Search

Our environmental DNA analysis identified Annamia-like operational taxonomic units (OTUs) from Lake Kasumigaura, Japan every summer season during the period from June 2012-May 2015. A strain from Lake Kasumigaura that agreed with an Annamia-like OTU (NIES-4383) was established with a cell-sorting machine. Based on the differences in morphology and 16S rRNA sequences, a new taxon is described: Annamia dubia Tuji, Yamaguchi et Niiyama sp. nov. A. dubia produces a microcystins that is also produced by A. toxica. Our 16S rRNA phylogenetical analysis reveals that the genus Annamia makes a monophyletic clade with the genera Geminocystis, Geminobacterium, and 'Cyanobacterium.' Although this clade agrees with Cyanobacteriaceae Komarek et al. (2014), this family is invalid based on the invalid genus Cyanobacterium and the type species Cyanobacterium stanieri. We propose the alternative name Geminocystaceae Tuji, Yamaguchi et Niiyama fam. nov. based on the genus Geminocystis.

Nasty smell of tap water supplied from Lake Biwa caused a great trouble. Then many researches have been conducted from the point of view of water supply management or water quality in Japan. The matter of this bad smell was identified as 2-methylisoborneol (2-MIB) and the source organism of this bad odor was then reported as Phormidium tenue and later two different cultured strains were established. One of these strains shows green color, produce 2-MIB, and is marked PTG. The other shows brown color, does not produce 2-MIB and is marked PTB. However their nomenclatural description has not been done yet and, in fact, they have morphological characters of genus Pseudanabaena rather than Phormidium. Pseudanabaena species are also observed in Lake Kasumigaura. PS1306 produces 2-MIB and other strain PS1303 has no smell. This study focuses on morphological and genetical (16S rRNA) comparison of strains from both lakes. In addition, the ultrastructure of cells of PTB and PTG are demonstrated. On the basis of this comparison we propose description of two new planktic species producing 2-MIB: Pseudanabaena foetida Niiyama, Tuji et Ichise sp. nov. and P. subfoetida Niiyama et Tuji sp. nov.

Umezakia natans M.Watan. was described by Dr. M. Watanabe in 1987 as a new species in the family of Stigonemataceae, following the rules of the Botanical Code. According to the original description, this planktonic filamentous species grows well in a growth media with pH being 7 to 9, and with a smaller proportion of sea water. Both heterocytes and akinetes were observed, as well as true branches developing perpendicular to the original trichomes in cultures older than one month. Watanabe concluded that Umezakia was a monotypic and only planktonic genus belonging to the family of Stigonemataceae. Unfortunately, the type culture has been lost. In 2008, we successfully isolated a new strain of Umezakia natans from a sample collected from Lake Suga. This lake is situated very close to the type locality, Lake Mikata in Fukui Prefecture, Japan. We examined the morphology of this U. natans strain, and conducted a DNA analysis using 16S rDNA regions. Morphological characters of the newly isolated strain were in a good agreement with the original description of U. natans. Furthermore, results of the DNA analysis showed that U. natans appeared in a cluster containing Aphanizomenon ovalisporum and Anabaena bergii. Therefore we conclude that Umezakia natans belongs to the family of Nostocaceae, not to Stigonemataceae.

The morphology of freshwater Cladophora (Chlorophyta) in Japan forming balls was investigated, together with apparently closely related forms not forming balls, and the classification of these forms was re-examined. Cladophora Sect. Aegagropila in Japan has been classified variously by previous authors, based on the form of the aggregates, cell shape and other criteria. The alga is perennial, floating or attached to substrates, with filaments 0.3–3.5 cm long, branched laterally, opposite or sometimes secund, and with cylindrical or clavate cells. Its morphology changes during growth and is also influenced by the environment. Various forms grow in the same habitat in nature, while two different forms were seen to develop the same shape when grown under standard conditions in the laboratory. The present author therefore proposes to unite all the lake ball-forming forms reported from Japan into one taxon, Cladophora aegagropila (L.) Rabenhorst. The growth-form of the alga appears to be influenced by...