Gloeotrichia natans Rabenhorst ex Bornet & Flahault (1886: 369)

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

Gloeotrichia natans Rabenhorst ex Bornet & Flahault (1886: 369) Fig. 25 A–F.

Thallus composed of gelatinous, irregularly spherical colonies, olive-green to brown in colour, 4–10 cm in diameter, attached to the substratum or less commonly free-floating. Filaments long, radially arranged within colonies, gradually tapered towards the ends, ± constricted at the cross walls. Sheath vase-like, widened, initially colourless, later yellow to yellow-brown in colour, layered and opened at the end. Vegetative cells initially shorter than broad to isodiametric, elongated towards the ends, up to 3 × longer than broad, 6.3–16.0 μm long × 4.0–7.0 μm broad. Heterocytes basal, single, ± spherical, 8.0–12.5 μm long × 9.0–12.0 μm broad. Akinetes cylindrical, slightly arcuate when mature, up to 5 × longer than broad, 25–55 μm long × 10–15 μm broad, with brown coloured exospore.

Specimens examined:—Cattle Ck at Gargett, Little Yabba Ck at Maleny Kenilworth Rd Crossing.

Other records:— Queensland: Canarvon Ck, A.B. Cribb 1964 (BRI 0700772), Bailey (1895), SE Queensland, McLeod (1975); Victoria: Bailey (1895), Entwisle (1994), Möbius (1895), Schmidle (1896).

Observations:—Known from coastal streams in south-east and northern Queensland. Observed forming olive-green to brownish gelatinous colonies on granitic cobbles and boulders, and large woody debris.