Calothrix cf. fusca Bornet & Flahault (1886: 364)

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

Calothrix cf. fusca Bornet & Flahault (1886: 364) Fig. 58 A–D.

Filaments solitary, or in small irregular groups, unbranched, up to 500 (–795) μm long, gradually tapering towards the ends. Sheath thin to thick, lamellated, often funnel-like widened, colourless to yellow-brown in colour. Trichomes continually narrowed towards the ends, 8.0–13.0 (–20.5) μm wide in the middle, usually constricted at the cross walls, ending in a fine, hair-like arrangement of hyaline cells. Vegetative cells at the base isodiametric or shorter than broad, 3.0–5.8 μm long × 6.0–10.5 μm wide, blue-green in colour; apical cells hyaline, 1.5–2 × longer than broad, 2.3–5.5 μm wide. Heterocytes basal, spherical to hemispherical 4.0–7.8 μm long × 5.5–8.5 μm wide. Akinetes not observed.

Specimens observed:—Rainbow Beach Fens, Great Sandy Natl Park, Cooloola Section, Amity Swamp, North Stradbroke Is.

Observations:—Growing in the metaphyton of acidic coastal wetlands amongst emergent sedges. C. fusca is considered cosmopolitan, more common in the northern temperate zone. Komárek (2013) considers material reported from various tropical and subtropical regions to be inconsistent with the original concept. Compare with C. furfosa Geitler from peaty pools in Indonesia.