Umezakia natans M.Watan. does not belong to Stigonemataceae but to Nostocaceae.

Abstract

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.

Review of the cyanobacterial genera implying planktic species after recent taxonomic revisions according to polyphasic methods: state as of 2014

“…the small planktic genera Cyanospira [in the original concept of Florenzano et al (1985) and Iteman et al (2002)] and Umezakia also probably belong to this family [acc. to Watanabe (1987), Niiyama et al (2011)]. …”

Sporadic Distribution and Distinctive Variations of Cylindrospermopsin Genes in Cyanobacterial Strains and Environmental Samples from Chinese Freshwater Bodies

“…To date, CYNs have been detected in Nostocales and Oscillatoriales species, including Cylindrospermopsis, Raphidiopsis (22,23), Aphanizomenon (24)(25)(26), Anabaena (27), Umezakia (28,29), Oscillatoria (30), and Lyngbya (31) spp. CYN-producing Cylindrospermopsis from Australia and Asia have been reported, whereas Cylindrospermopsis strains isolated from Europe and America are incapable of CYN production (32)(33)(34)(35)(36).…”

Molecular Basis and Phylogenetic Implications of Deoxycylindrospermopsin Biosynthesis in the Cyanobacterium Raphidiopsis curvata

“…U. natans was originally classified under the Stigonematales. However, based on recent molecular evidence, U. natans has recently been reevaluated and results showed that it belongs to the Nostocales (34). Therefore, the known CYN producers belong to the two orders of cyanobacteria, namely, Nostocales and Oscillatoriales.…”