Chrysosporum Zapomělová, Skácelová, Pumann, Kopp & Janeček (2012: 359)

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

Chrysosporum Zapomělová, Skácelová, Pumann, Kopp & Janeček (2012: 359)

Type: C. ovalisporum (Forti) Zapomělová, Skácelová, Pumann, Kopp & Janeček (2012: 359)

Filaments planktonic; trichomes solitary, straight or slightly flexuous, constricted at the cross walls.Apical cells conical, or tapered and elongated, often hyaline. Vegetative cells cylindrical, compressed during division, with aerotopes. Heterocytes intercalary, solitary, spherical, or slightly elongated. Akinetes widely ovoid, with brownish or yellow-brown epispore, remote from heterocytes.

A widely distributed genus of three species, all known from the plankton of freshwater lakes, reservoirs and rivers. Here two species are described from north-eastern Australia. Bibliography: Baker (1991), Stüken et al. (2006, 2009), Komárek & Mareš (2012), Zapomělová et al. (2012), Sukenik et al. (2012), Komárek (2016).

1. - Vegetative cells barrel-shaped, 4–8 μm broad, apical cells conically narrowed and tapered ................................................ C. bergii Vegetative cells cylindrical, 2.5–4.5 μm broad, apical cells elongated, narrowed and hyaline ................................. C. ovalisporum

Chrysosporum bergii (Ostenfeld) Zapomělová, Skácelová, Pumann, Kopp & Janeček (2012: 359) Fig. 6 A–E. Basionym: Anabaena bergii Ostenfeld (1908: 142)

Filaments planktonic; trichomes solitary, straight or slightly flexuous, narrowed towards the ends, constricted at the cross walls, with indistinct mucilaginous envelope. Vegetative cells barrel-shaped, ± spherical, 4–8 μm broad, with aerotopes; apical cells conically narrowed, tapered and hyaline. Heterocytes solitary, intercalary, spherical to ovate, 5–10 μm broad. Akinetes broadly ovate with dark brown epispore, intercalary, remote from the heterocytes, (12–) 20–24 μm long × 10–20 μm broad.

Specimens examined:—Condamine R. at Allan Tannock Weir, Boondooma Dam, Borumba Dam, Callide Dam, Cania Dam, Eungella Dam, Fred Haigh Dam, Glenlyon Dam, Julius Dam, Lake Clarendon, Maroon Dam, Paradise Dam, Peter Faust Dam, Fitzroy R. at Tartrus Weir, Teemburra Dam, Tinaroo Falls Dam.

Other records:— South Australia: Beetaloo Res., Baker (1991), Thornden Park Res., Humpage et al. (2013); New South Wales: Baker & Fabbro (2002); Victoria: Western Australia: Swan Coastal Plain Wetlands, Kemp (2009), Baldwin Park, Lee et al. (2014); Northern Territory: Palm Valley Ck, Humpage et al. (2013).

Observations:—Widely distributed throughout eastern Australia, however not often associated with bloom events.

Chrysosporum ovalisporum (Forti) Zapomělová, Skácelová, Pumann, Kopp & Janeček (2012: 359) Fig. 7 A–G. Basionym: Anabaena ovalisporum Forti 1911

Filaments planktonic; trichomes solitary, straight or slightly flexuous, narrowed towards the ends, constricted at the cross walls. Vegetative cells cylindrical, isodiametric up to 3 × as long as broad, 2.5–4.5 μm broad, with aerotopes; apical cells elongated and narrowed, tapered and hyaline. Heterocytes solitary, intercalary, spherical to sub-spherical, 5.0–8.5 μm broad. Akinetes broadly ovate with yellow-brown epispore, intercalary, remote from the heterocytes, 18–27 μm long × 10–15 μm broad.

Specimens examined:—Atkinson Dam, Bill Gunn Dam, Boondooma Dam, Borumba Dam, Bucca Weir, Burdekin Falls Dam, Callide Dam, Cania Dam, Coolmunda Dam, Crookes Dam, Pioneer R. at Dumbleton Weir, Fitzroy R. at Eden Bann Weir, Eungella Dam, Fred Haigh Dam, Haughton R. at Giru Weir, Glenlyon Dam, Julius Dam, Kinchant Dam, Burnett R. at Kirar Weir, Burnett R. at Ned Churchward Weir, Lake Clarendon, Leslie Dam, Maroon Dam, Mary R. at Mary R. Barrage, Moogerah Dam, Paradise Dam, Peter Faust Dam, Teemburra Dam, Tinaroo Falls Dam, Wuruma Dam.

Other records:— Queensland: Hervey Bay, Shaw et al. (1999); New South Wales: Cobaki L., Everson et al. (2009), Angourie Blue Pool, Humpage et al. (2013); South Australia: Baker & Fabbro (2002), Thornden Park Res., Humpage et al. (2013); Western Australia: Swan Coastal Plain Wetlands, Kemp (2009), Baldwin Park, Lee et al. (2014), Ling & Tyler (2000).

Observations:—Reported throughout Europe, typically from waters with higher conductivities. Widespread distribution throughout Australia, where it is known to produce the cyanotoxins cylindrospermopsin and deoxycylindrospermopsin ( Shaw et al. 1999, Everson et al. 2009). This species was the main constituent of a major bloom in the Murray R., New South Wales in 2016 where it affected Lakes Hume and Mulwala, and 400 km further downstream ( Willis 2016).

CUSPIDOTHRIX