Anabaena cf. oblonga Wildeman (1897: 50)

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

Anabaena cf. oblonga Wildeman (1897: 50) Fig. 38 A–E .

Filaments aggregated into fine mucilaginous mats, which can form into macroscopic columnar structures that rise from the benthos, sometimes detaching and freely floating in the water column. Trichomes flexuous to irregularly coiled and variously entangled, constricted at the cross walls, not attenuated towards the ends. Vegetative cells isodiametric or up to 2 × longer than wide, 4.3–7.7 μm long × 3–5 μm wide; apical cells conically rounded. Heterocytes intercalary, oval to cylindrical, 6.5–9.6 μm long × 4.2–5.5 μm wide. Akinetes cylindrical with bluntly rounded ends, sometimes slightly concave towards the centre, solitary or up to three in series, remote from heterocytes, 2.7–4.7 × longer than wide, 14–30 μm long × 4.4–6.3 μm wide, exospore smooth, colourless.

Specimens examined:—Walsh R. at Wrotham.

Observations:—Forming extensive mats and columnar structures in the benthos of shallow, off- stream pools on sand and gravel substrates. The observed material has akinetes which are slightly longer and narrower than typical A. oblonga , a tropical species originally described from Indonesia, but also known from Cuba and Argentina (Komárek 2013).

Figures

FIGURE 38. A–D Anabaena cf. oblonga; E Columnar structures of mature benthic mats. Scale bars = 20 μm