INTRODUCTION

Cyanobacteria or blue-green algae are a prokaryote that plays a role of primary producer through photosynthesis since about 3.5 billions years (Graham et al. 2009). The cyanobacteria are found in various environments even extreme conditions like hot spring, polar region, ultra-oligotrophic or high pH/salinity water (Parker et al. 1981; Wharton et al. 1983; Whitton 2012).

Planktonic cyanobacteria are floating algae suspended in slow moving water such as in a lake. They usually clustered within 30 cm of the water surface caused by colonization, mucilaginous sheath and gas vesicles. It often produces bright green or blue-green soup-like scums (Samuel et al. 2014).

Nowadays, freshwater habitats are threatened worldwide by blooming of cyanobacteria, such as Microcystis, Anabaena. Once they are bloomed, they can cause the problems in water environments and drinking water supplies by producing toxins like microcystin and anatoxin (Codd 1995; Kim et al. 1995). Therefore, continuous researches of cyanobacteria, especially Microcystis, Anabaena, Oscillatoria, and Aphanizomenon are being conducted worldwide (Park and Kim 1995; Park 2005; Lee et al. 2017).

The 4,617 taxa of cyanobacteria have been reported to AlgaeBase (Guiry and Guiry 2018), and 377 taxa have been reported in Korea (Kim 2015; Song and Lee 2017; Yim et al. 2017). Microcystis have been reported 51 taxa in worldwide, and 7 species in Korea. Anabaena have been reported 151 taxa in worldwide (Guiry and Guiry 2018), and 10 taxa in Korea.

For this study, we collected unrecorded cyanobacteria from fresh and brackish waters to add the algal flora of Korea.

MATERIALS AND METHODS

We collected planktonic cyanobacteria from nine sites in Korea from August 2016 to May 2018 (Fig. 1; Tables 1, 2). They were collected using phytoplankton net with mesh size 20 μm and diameter 30 cm (Sournia 1978). Each sample was sealed in sterile bottles and transported to the laboratory (Crispim et al. 2004). Measurement of salinity was performed by marine tester (DMT-10, DYS, Korea).

The samples were examined under BX53 light microscope at ×400-1,000 (Olympus, Tokyo, Japan) and photographed using AxioCam HRC camera (Carl Zeiss, Oberkochen, Germany). The taxonomic classification system was based on Komárek et al. (2014) and Algaebase (Guiry and Guiry 2018). In this study, identification of cyanobacteia referred to Hirose et al. (1977), Prescott (1982) Chung (1993), Komárek and Anagnostidis (1999, 2005), John et al. (2011) and Komárek (2013).

RESULTS AND DISCUSSION

Three genera and nine species of planktonic cyanobacteria were newly recorded in Korea. The newly recorded genera were Anathece, Chondrocystis and Geminocystis, and the newly recorded species were Anabaenopsis arnoldii, Anathece smithii, Chondrocystis dermochroa, Coelosphaerium aerugineum, Eucapsis microscopica, Geminocystis herdmanii, Microcystis panniformis, Synechococcus nidulans and Woronichinia karelica.

Colonies are free-living and more or less irregular or irregular- polygonal. Colonies are surrounded by packet-like outline, gelatinous, laterally usually flattened or (in masses) slimy mucilage envelopes. They are composed of numerous partial subcolonies. Subcolonies are surrounded by more or less cubic or polygonal flattened, widened, colourless, delimited slime, cells with individual thin, gelatinous, slightly stratified envelopes. Envelopes are partially thickened. Reproduction is occured by small subcolonies after colony disintegration. This genus is newly recorded in Korea.

Chondrocystis dermochroa (Nägeli ex Kützing) Komárek and Anagnostidis 1995 (Fig. 2)

Synonym:Gloeocapsa dermochroa Nägeli ex Kützing 1849

Colony size is microscopic or rarely macroscopic. Colonies are more or less spherical, hemispherical or oval. Large colonies are composed of very densely packed and small subcolonies. Subcolonies are spherical or polygonally- rounded, and composed of clustered cells. Mucilaginous envelope that surround the subcolony is narrow and firm, but later diffluent. Mucilaginous envelope forms single or slightly lamellated layers. The cell is spherical and bluegreen in color. Cell diameter is 1.5-3 μm.

Ecology: This species appears in freshwater and subaerophytic habitat. This species lives usually in limestone areas or on rocks with periodically flowing water, but rarely in the water-level zone of streams (Komárek and Anagnostidis 1999). We collected it from midstream of Nakdong river.

Distribution: Arctic: Svalbard (Matula et al. 2007); North America: Arkansas (Smith 2010).

Site of collection: Yulji-gyo, Changnyeong-gun, Gyeongsangnam- do (August 24, 2016).

Specimen Locality: ACKU2018MD03

Genus Geminocystis Korelusová et al. 2009

Cells are solitary, and spherical or slightly oval, after division hemispherical. Cell’s diameter is 3-10 μm. Mucilage is abscent or narrow, fine, colorless, and usually diffluent and indistinct mucilaginous envelopes. Cell contents are homogeneous, without separation of centro- and chromatoplasma, sometimes with lengthwise striation (thylakoids situated in cells lengthwise). Color of cells is pale blue-green, bright-green, grey, or pinkish. Cells are divided by binary fission into two morphologically equal, hemispherical daughter cells, which reach the original globular shape before next division. This genus is newly recorded in Korea.

Geminocystis herdmanii Korelusová et al. 2009 (Fig. 3)

They are solitary, not forming a colony. The cell is spherical but hemispherical after cell division by binary fission. Cell contents are homogeneous or has slightly irregularly keritomic thylakoid content. Thylakoids in cells are arranged irregularly or in parallel. The cell is blue-green in color and diameter is 3-5 μm.

Ecology: This species appears in freshwater and planktonic habitat. They lives in oligotrophic lakes (Komárek and Anagnostidis 1999). We collected it from mesotrophic reservoir at mountainside.

Distribution: North America: Wisconsin (Korelusová et al. 2009).

Site of collection: Yonggok-reservoir, Jangdong-myeon, Jangheung-gun, Jeollanam-do (August 7, 2017).

Specimen Locality: ACKU2018MD02

Family Synechococcaceae Komárek and Anagnostidis 1995

Genus Anathece (Komárek and Anagnostidis) Komárek et al. 2011

Colonies are multicellular, irregular, microscopic or rarely macroscopic. They are composed of irregularly arranged cells and surrounded by fine, colourless, homogeneous and diffluent mucilage, but sometimes they disintegrated in solitary cells. Colonies fragment into solitary cells. Mostly planktonic, rarely benthic. Cells are oval to rodlike, straight or slightly arcuate, without own mucilaginous envelopes. Cells are pale-grey, blue-green or olive-green colored, and (0.8)1-2 (6) μm long, 0.3-2 μm width. Cell division is occured by binary fission, perpendicular to the long axis. This genus is newly recorded in Korea.

Anathece smithii (Komárková-Legnerová and Cronberg) Komárek et al. 2011 (Fig. 4)

Synonym: Aphanothece smithii Komárková-Legnerová and G. Cronberg 1994

Colonies are microscopic and free floating. Colonies are more or less spherical or irregular in outline and sometimes elongated. Cells that form colonies are usually arranged regularly, not very densely. Mucilage is colorless and usually wraps all the cells by a narrow, hyaline. The cell is more or less oval to cylindrical and straight. The cell is pale bluegreen or grey-blue in color. The cell’s length is 2-3.5 μm and width is 1-1.5 μm.

Ecology: This species occurs in freshwater and planktonic habitat. They lives in mesotrophic and slightly eutrophic, usually large water bodies (Komárek and Anagnostidis 1999). In this study, we collected it from eutrophic brackish waterway (salinity 5.1‰).

Distribution: Australia and New Zealand: Queensland (Bostock and Holland 2010).

Site of collection: Eutrophic waterway, Hupo-myeon, Uljin- gun, Gyeongsangbuk-do (September 23, 2017).

Specimen Locality: ACKU2017IR10

Genus Synechococcus Nägeli 1849

Synechococcus nidulans (Pringsheim) Komárek in Bourrelly 1970 (Fig. 5)

Synonym:Lauterbornia nidulans Pringsheim 1968

Cells are solitary and free-floating. The cells are straight or sometimes slightly sigmoid or arcuate and without mucilage. Cell contents are homogeneous and pale blue-green in color. Cell’s length is 1.5-6.5 μm and width is 1-1.5 μm.

Ecology: This species appears in freshwater and planktonic habitit. They lives in small water bodies, ditch ponds and large lakes (Komárek and Anagnostidis 2005). We collected it from eutrophic and brackish waterway (salinity 1‰).

Distribution: South America: Brazil (Lopes et al. 2005); Australia and New Zealand: Queensland (Bostock and Holland 2010).

Site of collection: Goraebuldae-gyo, Byeonggok-myeon, Yeongdeok-gun, Gyeongsangbuk-do (March 30, 2018).

Specimen Locality: ACKU2018IR06

Anabaenopsis arnoldii Aptekar 1926 (Fig. 6)

Trichomes are free-floating, solitary or clustered in small, irregular colonies, irregularly screw-like coiled, with 1-12 coils. The coil width is ±25 μm, and the length is 7-30 μm, constricted at the cross-walls, with wide, colourless, diffluent mucilaginous envelopes. Cells are spherical or widely barrel-shaped, yellow-green. Heterocytes are spherical, 8-10×7-10 μm.

Ecology: This species occurs in freshwater ponds and lakes (Komárek 2013). We collected it from seawall.

Distribution: Russia (Medvedeva and Nikulina 2014); Australia and New Zealand: Queensland (Bostock and Holland 2010).

Site of collection: Deep-water of seawall, Inju-myeon, Asan-si, Chungcheongnam-do (August 7, 2017).

Specimen Locality: ACKU2017NR17

Coelosphaerium aerugineum Lemmermann 1898 (Fig. 7)

Colonies are free floating and spherical. However, sometimes they consist of 2-3 hemispherical subcolonies with irregularly and sparsely or densely aggregated cells (where they never touch one another). Cells are spherical or hemispherical after division and have a bit of a granule, but without gas vesicles. The cells are usually bright blue-green in color and diameter is 2.2-3.5 μm.

Ecology: This species appears in freshwater and mainly planktonic habitit. They lives in eutrophic to mesotrophic water bodies (Komárek and Anagnostidis 1999). We collected it from brackish waterway (salinity 0.2‰).

Distribution: North America: Arkansas (Smith 2010).

Site of collection: Okpo-gyo, Dongjin-myeon, Buan-gun, Jeollabuk-do (September 26, 2017).

Specimen Locality: ACKU2017IR01

Genus Woronichinia Elenkin 1933

Woronichinia karelica Komárek and Komárková- Legnerová 1992 (Fig. 8)

Colonies are solitary and irregularly spherical or oval, and they are composed of subcolonies when matured. The colonies are composed of cells that arranged radially and densely packed in the peripheral layer, and which grow up to 50 μm in diameter. The cells joined by the faintly visible, colorless and thick stalks radiating from the colonial center. The cells are more or less elongated and obovated with a homogeneous contents and pale blue-green in color. The cell’s length is 3-3.5 μm and width is 1.5-2 μm.

Ecology: This species appears in freshwater and planktonic habitat. They lives in oligo- or mesotrophic lakes and ponds of northern part of the whole temperate zone (Komárek and Anagnostidis 1999). We collected it from downstream of Nakdong river.

Distribution: Asia: Russia (Medvedeva and Nikulina 2014).

Site of collection: Gupodae-gyo, Gupo-dong, Buk-gu, Bu-san (June 9, 2017).

san (June 9, 2017). Specimen Locality: ACKU2017NR18

Eucapsis microscopica (Komárková-Legnerová and G. Cronberg) Komárek and Hindák 2016 (Fig. 9)

Synonym:Chroococcus microscopicus Komárková-Legnerová and G. Cronberg 1994

Colonies are microscopic and free floating. They are composed of numerous cumulus-like densely packed groups of cells. Mucilage is colorless, without structure, delicate and more or less clearly delimited or diffluent. Cells are spherical and usually 4-8 cells forms subcolonies arranged regularly and surrounded by a mucilage, which is easily recognizable after staining or in phase contrast. The cell contents are homogeneous and pale blue-green in color. The cell’s diameter is 0.9-1.3 μm.

Ecology: This species appears in freshwater and planktonic habitit. They lives in mesotrophic lakes; known only from Sweden, but probably more widely distributed in northern lakes (Komárek and Anagnostidis 1999). We collected it from mesotrophic and brackish wetland (salinity 6.6‰).

Distribution: Europe: Baltic Sea (Hällfors 2004).

Site of collection: Soreapogu-wetland, Nonhyeon-dong, Namdong-gu, Incheon (May 4, 2018).

Specimen Locality: ACKU2018IR01

Microcystis panniformis Komárek, Komárková-Legnerová, Sant’Anna, Azevedo and Senna 2002 (Fig. 10)

Colonies are microscopic and macroscopic. The young colonies are subsphaerical close to a sphere; as they mature, they get somewhat flattened, growing irregularly into a lobe-shape. Cells that form colonies are arranged homogeneously or slightly clathrate. Mucilage is colorless, homogeneous, diffluent and indistinct of the margin. Reproduction of cells happen on the margin of matured colonies. Cells are spherical or hemispherical after division, and they have gas vesicles. The cells are yellow-green or olive brown in color, and their diameter is 3.5-4.5 μm.

Ecology: This species are founded in freshwater and planktonic habitit. They lives in subtropical eutrophic lakes and ponds (Komárek et al. 2002). We collected it from eutrophic and brackish paddy pond (salinity 0.6‰).

Distribution: Australia and New Zealand: Queensland (Bostock and Holland 2010).

Site of collection: Paddy field nearby Jangsu-stream, Bangsan- dong, Siheung-si, Gyeonggi-do (May 4, 2018).

Specimen Locality: ACKU2018IR02