Dolichospermum helicoideum (Bernard) Wacklin, Hoffmann & Komárek (2009)

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

Dolichospermum helicoideum (Bernard) Wacklin, Hoffmann & Komárek (2009) Fig. 13 A–F.

Trichomes planktonic, solitary, ± regularly spirally coiled, without mucilaginous sheath, constricted at the cross walls; coils 25–40 μm in diameter. Vegetative cells barrel-shaped, isodiametric or up to 1.8 × longer than broad, 3.6–6.0 μm long × 3.0–3.8 μm broad, with aerotopes; apical cells sometimes slightly narrowed and elongated. Heterocytes solitary, spherical to ellipsoidal, 4.2–5.2 μm long, 3.9 × 4.4 μm broad. Akinetes cylindrical, slightly arcuate, up to 3.3 × longer than broad, 9.4–18.2 μm long × 3.7–5.9 μm broad, single or up to two in series, adjacent to or remote from the heterocytes.

Specimens examined:—Ben Anderson Barrage, Bjelke-Petersen Dam, Boondooma Dam, Bowen R. Weir, Bucca Weir, Callide Dam, Cania Dam, Coolmunda Dam, Eungella Dam, Glenlyon Dam, Kirar Weir, Ned Churchward Weir, Paradise Dam, Wuruma Dam.

Other records:— Queensland: central Queensland as Anabaena flos-aquae f. lemmermannii, Fabbro & Duivenvoorden (1993) .

Observations:—Known from tropical areas of south-east Asia and South and Central America. In Australia, it is commonly misreported as D. flosaquae , however D. helicoideum differs by the elongated cylindrical shape of akinetes, which may be either remote or adjacent to the heterocyte.