INTRODUCTION

Though they are microscopic in size and simple in cellular structure, the cyanobacteria played dramatic roles in Earth’s remote past, photosynthetic cyanobacteria produced Earth’s first oxygen atmosphere, thereby reducing carbon dioxide levels and influencing the global climate. Cyanobacteria remain important today, having both positive and negative impacts from the human perspective. Some cyanobacteria have potential biotechnological applications in producing medicinal compounds and hydrogen-based energy. The tendency of many cyanobacteria to produce toxins and form harmful blooms is an increasingly serious concern worldwide (Robarts and Zohary 1987; Kim et al. 1995; Graham et al. 2009). The harmful cyanobacterial genera that mainly cause bloom, such as Microcystis, Oscillatoria, Anabaena and Aphanizomenon have been intensively studied.

Filamentous cyanobacteria are consecutively connected, either long or short; they mainly attach to submerged substrates including aquatic plants, submerged land plants, and rocks, and sometimes they free-float. Although filamentous cyanobacteria produce toxins including Anatoxin (Anabaena), their main problem is bloom caused by the production of odorous substances such as Geosmin and 2-MIB in drinking water supplies (Saadoun et al. 2001; You et al. 2013).

The 4,598 taxa of cyanobacteria have been reported to AlgaeBase (Guiry and Guiry 2017), and 343 taxa have been reported in Korea (Kim 2015). In Oscillatoria, 305 taxa have been reported in AlgaeBase, and 18 have been reported in Korea, and in Phormidium, 211 have been reported in AlgaeBase, and 42 taxa has been reported in Korea. Fewer taxa have been reported for Anagnostidinema, Komvophoron, Hydrpcoleum and Pseudanabaena in Korea, but studies on Korean cyanophytes are still scarce. For this study, we collected and identified unrecorded filamentous cyano- phytes in Korea from freshwater streams and ponds and brackish water to add the cyanophycean flora of Korea.

MATERIALS AND METHODS

We collected filamentous cyanobacteria from both freshwater and brackish water from small streams in Sangju-si, Gyeongsangbuk-do, and Uljin-gun, Gangwon-do, and from a small pond and a bay in Jeju-do from July 2016 to May 2017 (Table 1). We collected planktonic cyanobacteria with a 20 μm-mesh phytoplankton net; benthic cyanobacteria, we collected the samples by scrubbing submerged plants and rocks. We stored and sealed each sample opaque containers and transported them to the laboratory (Crispim et al. 2004); some samples were fixed with 1% formalin aldehyde. We made enrichment cultures of the algae in BG-11 (Sigma C3061), and deposited the samples at the Nakdonggang National Institute of Biological Resources and the National Institute of Biological Resources. The samples were examined under an Olympus BX41 light microscope (at ×400- 1,000; Olympus, Tokyo, Japan) and photographed using an AxioCam HRC camera (Carl Zeiss, Oberkochen, Germany).

The taxonomic classification system was based on Komárek et al. (2014) and AlgaeBase (Guiry and Guiry 2017), and we identified the cyanobacteria following Prescott (1982), Hirose et al. (1977), Chung (1993), Wehr and Sheath (2003), Komárek and Anagnostidis (2005), and John et al. (2011).

RESULTS AND DISCUSSION

In this study, one genus and six species of filamentous cyanobacteria were newly recorded in Korea. The newly recorded genus was Borzia, and the newly recorded species were Anagnostidinema acutissimum, Komvophoron bourrellyi, Hydrocoleum stankovicii, Borzia trilocularis, Phormidium tinctorium and Pseudanabaena lohchoides.

The characteristics of the species are as follows.

Order Oscillatoriales

Family Coleofasciculaceae

Genus Anagnostidinema

Anagnostidinema acutissimum (Kufferath) Strunecký, Bohunická, J. R. Johansen and J. Komárek 2017 (Fig. 1)

The thallus is mucilaginous and membranaceous. These cyanobacteria consists of fine blue-green trichome bundles and sometimes free-floating solitary trichomes. Trichomes are blue-green in color and straight, but a small number of cells are attenuated and bent at the ends. At the crosswalls, constriction occurs inconspicuously or not, and there are cyanophycin granules near the cross-wall. The cells are 1.5-2.5 μm and 3-7 μm long.

Ecology: This species lives in freshwater and is benthic in shallow stagnant water. We collected it from submerged plants in freshwater streams.

Distribution: Arctic: Svalbard (Spitsbergen; Matula et al. 2007); Europe: Georgia (Barinova et al. 2011), Germany (Täuscher 2011, 2014), Lithuania (Karosiene and Kasperoviciene 2009), Romania (Caraus 2012, 2017); North America: Arkansas (Smith 2010); Asia: Russia (Medvedeva and Nikulina 2014)

Site of collection: Gyonchun-gyo, Gyeongsangnam-do (July 28, 2016)

Specimen Locality: KTSN 120000207789

Order Oscillatoriales

Family Gomontiellaceae

Genus Komvophoron

Komvophoron bourrellyi X. Turon, M. Hernández- Mariné and J. Catalan 1991 (Fig. 2)

Trichomes are solitary, short, and composed of 2-50 cells. They are straight or bent in shape and deeply constricted at the cross-walls. The cell is red in color, barrel-shaped, and homogeneous without granules or aerotopes. The apical cell is rounded or hemispherical in shape and is 1.8-2.2 μm wide and 1-2.3 μm long.

Ecology: This species lives in marine areas in epibiotes on ascidians from the Mediterranean Sea (Turon et al. 1991), but we collected it from submerged plants in freshwater streams.

Distribution: Europe: Spain (De la Rosa Álamos 2016; Gallardo et al. 2016)

Site of collection: Jungdong-gyo, Gyeongsangnam-do (September 20, 2016)

Specimen Locality: KTSN 120000207790

Order Oscillatoriales

Family Microcoleaceae

Genus Hydrocoleum

Hydrocoleum stankovicii Cado 1958 (Fig. 3)

Filaments are solitary or in groups and do not form compact thalli; they are not branched or calcified. The sheath is fine, colorless, and uneven from the outside, containing several blue-green trichomes, and it does not show constriction at the cross-walls. The trichome is attenuated toward the end, and the apical cell is conical-round and has conical calyptra. The cells are approximately 6 μm wide and 3.5-6 μm long.

Ecology: This species lives in freshwater, we collected it from submerged plants in freshwater streams.

Distribution: Yugoslavia (Komarek and Anagnostidis 2005)

Site of collection: Jungdong-gyo, Gyeongsangnam-do (Sep- tember 20, 2016)

Specimen Locality: KTSN 120000005865

Order Oscillatoriales

Family Phormidiaceae

Genus Borzia F. Cohn ex M. Gomont 1892

Trichomes are solitary or aggregated in small groups. They are short, consisting of up to eight cells, and are composed of simple structures. The species is normally immotile and can be constricted at the cross-walls. There is no sheath; however, thin mucilage is found occasionally. The cell is cylindrical or barrel shaped, and the apical cell is rounded. In terms of dimensions, it is isodiametric.

Order Oscillatoriales

Family Phormidiaceae

Genus Borzia

Borzia trilocularis Cohn ex Gomont 1892 (Fig. 4)

Trichomes are solitary and straight, they are very short and lack mucilaginous sheath. They are straight, normally consisting of three to eight cells. They are blue-green in color and distinctly constricted at the ungranulated crosswalls. They can be intensely creeping or immotile. The cell is barrel shaped, with large prominent granules inside. The apical cell is hemispheric. The cell is 5-8 μm wide and 2-6.1 μm long.

Ecology: This species lives in freshwater or terrestrial water, and we collected it from submerged plants in the brackish water of a small bay (salinity 18‰).

Distribution: Europe: Georgia (Barinova et al. 2011), Romania (Caraus 2012, 2017), Spain (Alvarez-Cobelas and Gallardo 1988); North America: Arkansas (Smith 2010); South America: Argentina (Tell 1985), Brazil (Bicudo 1965; Azevedo et al. 1996; Werner 2010); South-west Asia: India (Chatterjee and Keshri 2005; Gupta 2012), Iran (Afsharzadeh et al. 2003), Iraq (Maulood et al. 2013)

Site of collection: 57-9, Ojo-ri, Jeju-do (May 20, 2017)

Specimen Locality: KTSN 120000212682

Order Oscillatoriales

Family Phormidiaceae

Genus Phormidium

Phormidium tinctorium Kützing ex Gomont 1892 (Fig. 5)

Thallus is tufty with fasciculated and penicillated filaments. It is dark olive to brown in color, forms gelatinous or membranaceous mats, and attaches to substrates. Filaments are nearly straight and densely arranged in parallel. The sheath is fine, strongly mucilaginous, and diffluent. Trichomes are indistinctly to distinctly constricted and ungranulated at the cross-walls; sometimes they are lengthily attenuated at the ends. The apical cell is either acute-conical or cylindrical-conical and without calyptra. The cell is 6-8.5 μm wide and 5-11 μm long.

Ecology: This species lives in freshwater and is benthic (mainly on stony substrate) in streams and rivers. We collected this species from submerged stone in a brackish stream (salinity 0.1‰).

Distribution: Europe: Germany (Täuscher 2014), Romania (Caraus 2002, 2017), Spain (Alvarez-Cobelas and Gallardo 1988); Asia: South China Sea (Phang et al. 2016); Pacific Islands: Hawaiian Islands (Sherwood 2004)

Site of collection: Uljin-daegyo, Gangwon-do (May 31, 2017)

Specimen Locality: KTSN 120000212680

Order Synechococcales

Family Pseudanabaenaceae

Genus Pseudanabaena

Pseudanabaena lonchoidesAnagnostidis 1961 (Fig. 6)

Thallus is usually thin, fine, and indefinite. It forms a mat to attach to substrates, but it can be free-floating. Trichomes are commonly bright blue-green in color and less frequently bluish to greenish. They are straight or variously curved but sometimes slightly screw-like or coiled in shape. Normally, they are densely arranged, entangled, or parallel. The trichomes vary in length, and the cross-walls are constricted and not granulated. The trichomes have large or small aerotopes like spherical or lance-like at each end. The apical cell is acute-conical and does not have calyptra or thickened cell walls. The cell is 0.6-1.3 μm wide and 0.8-1.8 μm long.

Ecology: This species lives in thermal, brackish and salty water. We collected it from submerged plants in a eutrophic salt water pond (salinity 35 ‰).

Distribution: Europe: Turkey (Europe) (Aysel 2005); South America: Argentina (Rodriguez et al. 2006)

Site of collection: 83, Ojo-ri, Jeju-do (May 19, 2017)

Specimen Locality: KTSN 120000212679