Aphanizomenon gracile (Lemmermann) Lemmermann (1907: 193)

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

Aphanizomenon gracile (Lemmermann) Lemmermann (1907: 193) Fig. 5 A–H.

Basionym: Aphanizomenon flosaquae var. gracile Lemmermann (1898: 204)

Filaments planktonic; trichomes solitary, not forming fascicles, isopolar, sub-symmetrical, straight or slightly flexuous, constricted at the cross walls. Vegetative cells isodiametric to short cylindrical, 2.8–6.5 (–9) μm long × 2.5–5.5 μm broad, with aerotopes; apical cells rounded or club-shaped, sometimes slightly elongated and narrowed. Heterocytes intercalary, solitary, ovate to sub-cylindrical, 3.5–7.5 μm long × 3.0–5.0 μm broad. Akinetes solitary, long cylindrical, often with a collar-like extension at either end which extends over the adjacent vegetative cells, 7.5–15.0 (–42) μm long × (2.5–) 4.0–6.5 (–8.0) μm broad.

Specimens examined:—Atkinson Dam, Ben Anderson Barrage, Bill Gunn Dam, Bjelke-Petersen Dam, Boondooma Dam, Borumba Dam, Cania Dam, Claude Wharton Weir, Coolmunda Dam, Eden Bann Weir, Eungella Dam, Giru Weir, Glen Niven Dam, Glenlyon Dam, Ibis Dam, Kinchant Dam, Kirar Weir, Lake Clarendon, Leslie Dam, Mirani Weir, Moogerah Dam, Paradise Dam, Peter Faust Dam, Tartrus Weir, Teemburra Dam, Tinaroo Falls Dam, Wuruma Dam, Wyndham Dam.

Other records:— Queensland: Ling & Tyler (2000); South Australia: River Murray at Murtho, Morgan, Swan Reach in Lake Alexandrina, Lake Albert at Narrung and Meningie, Warren Res., Strathalbyn Res., Dawesley farm dam, Mount Lofty Ranges, Bundaleer Res., Barcoota Res., Baker (1991); Victoria: Violet Ck Res., Lance Ck Res., Lake Whitton, Sea L. Storage, Baker (1991), Ling & Tyler (2000); New South Wales: River Murray at Yarrawonga, Euston, Redcliffs, Merbein, Sullivan et al. (1988), Hume Dam, Humpage et al. (2013); Northern Territory: Magela Ck, Thomasson (1986); Western Australia, Chelodina Wetlands, Lee et al. (2014).

Observations:—Widespread species, known from the plankton of mesotropic lakes and reservoirs throughout the temperate zone (Komárek 2013). In Australia is has been widely reported, however it is not typically a bloom forming species and has not been associated with cyanotoxin production. Trichomes lacking akinetes may be confused with Sphaerospermopsis aphanizomenoides .

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