Anabaena Bory de Saint-Vincent ex Bornet & Flahault (1886: 224)

Mcgregor, Glenn B., 2018, Freshwater Cyanobacteria of North-Eastern Australia: 3. Nostocales, Phytotaxa 359 (1), pp. 448-450 : 448-450

Anabaena Bory de Saint-Vincent ex Bornet & Flahault (1886: 224)

Type: A. oscillarioides Bory de Saint-Vincent ex Bornet & Flahault (1886: 233)

Filamentous; trichomes solitary or aggregated into macroscopic mats on the substrate, straight or variously coiled and twisted, constricted at the cross walls, always without firm sheaths, sometimes with hyaline, colourless, diffluent mucilage; trichomes often moniliform, isopolar, metameric with heterocytes developing solitary and intercalary, which are generally regularly spaced. Vegetative cells cylindrical, barrel-shaped or spherical, shorter or longer than wide, pale or bright blue-green or olive-green in colour, without aerotopes, sometimes with granular contents; apical cells may be slightly elongated, conical, conical rounded or spherical. Heterocytes spherical, widely oval or cylindrical, sometimes elongated, usually slightly larger than vegetative cells. Akinetes spherical, oval or cylindrical, solitary or many in series, intercalary, developing paraheterocytically, adjacent to or near the heterocytes. Cells divide crosswise and grow to the original size before the next division; without meristematic zones. Reproduction by trichome fragmentation and by akinete production.

A widely distributed genus of 150 species known from freshwater lakes and reservoirs, rivers and estuaries. Here 10 species are described from north-eastern Australia. Many traditional Anabaena species which produce aerotopes, and are typically planktonic, were transferred to Dolichospermum ( Wacklin et al. 2009) . Bibliography: Willame et al. (2006), Wacklin et al. (2009), Komárek (2013), Komárek et al. (2014), Kust et al. (2015), Kozlíková-Zapomělová et al. (2016).

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Akinetes always remote from heterocytes..........................................................................................................................................2 Akinetes either remote from, or adjacent to heterocytes....................................................................................................................5 Apical cells bluntly rounded, and generally undifferentiated.............................................................................................................3 Apical cells conically rounded...........................................................................................................................................................4 Akinetes cylindrical with bluntly rounded ends, 15.5–17.0 μm long × 5.0–6.5 μm wide, exospore undifferentiated........... A. sp. A Akinetes rounded cylindrical, 15.5–24.0 μm long × 7.0–11.5 μm wide, exospore radially striated ........................ A. cf. alatospora Vegetative cells isodiametric or up to 2 × longer than broad, akinetes cylindrical, sometimes concave towards the centre .............. ....................................................................................................................................................................................... A. cf. oblonga Vegetative cells isodiametric or shorter than broad, akinetes uniformly cylindrical ...................................................... A. inaequalis Filaments straight or only slightly flexuous.......................................................................................................................................6 Filaments flexuous to irregularly coiled and contorted......................................................................................................................8 Heterocytes cylindrical, L:B ratio 1.4–2.1 ........................................................................................................................ A. cf. willei Heterocytes spherical to ovate............................................................................................................................................................7 Akinetes widely cylindrical, flatly rounded at the ends ..................................................................................................... A. torulosa Akinetes oblong-ovate to cylindrical with rounded ends .......................................................................................... A. oscillarioides Apical cell conically rounded.......................................................................................................................................... A. cylindrica Apical cell bluntly rounded and generally undifferentiated...............................................................................................................9 Akinetes rounded cylindrical, exospore covered with long flexuous hair-like processes........................................... A. wallumensis Akinetes long cylindrical with rounded ends, exospore smooth........................................................................... A. cf. augustumalis