Raphidiopsis mediterranea Skuja (1937: 23)

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

Raphidiopsis mediterranea Skuja (1937: 23) Fig. 20 A–F .

Filaments planktonic; trichomes straight or slightly bent, narrowed and sharply pointed at both ends, solitary or aggregated into fasciculated, parallel arranged clusters, not constricted at the cross walls. Vegetative cells cylindrical, 2–5 × longer than broad, 1.0–3.5 μm broad, blue-green in colour, with aerotopes. Apical cells elongated and sharply pointed. Akinetes intercalary, barrel-shaped or bluntly cylindrical oval, single or 2–4 in series, with smooth, colourless or brownish epispore.

Specimens examined:—Lake Clarendon, Bill Gunn Dam, Wuruma Dam, Atkinson Dam, Borumba Dam, Cania Dam, Wyndham Dam, Bjelke-Petersen Dam, Peter Faust Dam, Fitzroy R. at Moura Weir, Fitzroy R. at Eden Bann Weir, Fitzroy R. at Neville Hewitt Weir, Fitzroy R. at Bingegang Weir, Fred Haigh Dam, Coolmunda Dam, Pioneer R. at Marian Weir, Pioneer R. at Dumbleton Weir, Pioneer R. at Mirani Weir, Teemburra Dam, Fairbairn Dam, Fitzroy R. at Tartrus Weir, Julius Dam, Moogerah Dam, Leslie Dam, Kinchant Dam, Callide Dam, Tinaroo Falls Dam, Burnett R. at Ben Anderson Barrage, Burnett R. at Kirar Weir, Burnett R. at Jones Weir, Tinaroo Falls Dam, Ibis Dam, Warrego R. at Allan Tannock Weir, Eungella Dam.

Other records:— Baker & Fabbro (2002).

Observations:—A widely distributed species, although generally considered more common throughout the tropics. In Australia, it has been infrequently reported from the plankton of mesotrophic reservoirs. The low frequency at which it has been reported is not surprising given its morphological similarity to R. raciborskii ( McGregor & Fabbro 2000) . In R. raciborskii heterocytes are solitary, terminal, and develop at one or both ends of the trichome, whereas in R. mediterannea heterocytes are lacking. Given that heterocytes are not always expressed in R. raciborskii populations, distinction from R. mediterannea is often based on differential apical cell morphology alone. Morphological similarities between these two species therefore, may result in misidentifications ( Mohamed 2006, Alster et al. 2010). Australian populations of R. mediterannea produce the cyanotoxins cylindrospermopsin and deoxy-cylindrospermopsin ( McGregor et al. 2011).

Raphidiopsis raciborskii (Wołoszyńska) Anguilera, Berrendero Gómez, Kaštovský, Echenique & Salerno (2018: 144) Fig. 21 A–H .

Basionym: Anabaena raciborskii Wołoszyńska (1912: 684)

Trichomes solitary, straight, coiled or sigmoidal, often slightly attenuated towards the apices. Vegetative cells quadrate to cylindrical, not or slightly constricted at the cross walls which are often indistinct, 2.0–8.5 μm long × 2.0–4.5 μm broad, with aerotopes. Heterocytes long ovoid or conical, sometimes slightly curved, terminal at one or both ends of the trichome, 3.5–11 μm long × 2.5–4.0 μm broad. Akinetes oblong-ovate to cylindrical and rounded at the ends with curved margins in coiled trichomes, 7.5–16.0 μm long × (2.5–) 3.5–4.5 μm broad, solitary or in series, typically remote from the heterocytes.

Specimens examined:—Atkinson Dam, Beardmore Dam, Bill Gunn Dam, Bjelke-Petersen Dam, Boondooma Dam, Borumba Dam, Bowen R. Weir, Burdekin Falls Dam, Burnett R. at Ben Anderson Barrage, Burnett R. at Jones Weir, Burnett R. at Kirar Weir, Burnett R. at Ned Churchward Weir, Callide Dam, Cania Dam, Condamine R. at Chinchilla Weir, Coolmunda Dam, Copperfield Dam, Corella Dam, Crookes Dam, East Leichhardt Dam, Dowse Lagoon, Eungella Dam, Fairbairn Dam, Fitzroy R. at Bedford Weir, Fitzroy R. at Bingegang Weir, Fitzroy R. at Claude Wharton Weir, Fitzroy R. at Eden Bann Weir, Fitzroy R. at Glebe Weir, Fitzroy R. at Moura Weir, Fitzroy R. at Neville Hewitt Weir, Fitzroy R. at Tartrus Weir, Fitzroy R. at Theodore Weir, Fred Haigh Dam, Gattonvale offstream storage, Glen Niven Dam, Glenlyon Dam, Haughton R. at Giru Weir, Julius Dam, Kinchant Dam, Kolan R. at Bucca Weir, L. Clarendon, Lake Moondarra, Leslie Dam, Marian Weir, Maroon Dam, Mary R. Barrage, Moogerah Dam, Moura offstream storage, Paradise Dam, Peter Faust Dam, Pioneer R. at Dumbleton Weir, Pioneer R. at Mirani Weir, Six Mile Ck at Bajool Weir, Somerset Dam, Stag Ck Weir, Teemburra Dam, Tinaroo Falls Dam, Warrego R. at Allan Tannock Weir, Wivenhoe Dam, Wuruma Dam, Wyndham Dam.

Other records:— Queensland: Palm Is., Hawkins et al. (1985), Ling & Tyler (2000); New South Wales: River Murray at Heywoods, Yarrawonga, Torrumbarry, Swan Hill and Euston, Sullivan et al. (1988); Victoria: Bonyaricall Ck, U/S Robinvale, Swan Reach, L. Alexandrina at Goolwa, Baker (1991); South Australia: Big Bend Lagoon, Murray R., Baker (1991); Northern Territory: Ling & Tyler (2000).

Observations:—Pantropical species, widely distributed throughout tropical regions and warmer areas of the temperate zone where it has more recently been considered an invasive species ( Antunes et al. 2015, Moreira et al. 2015). Reported from lakes, reservoirs and rivers in every mainland state of Australia (as Cylindrospermopsis raciborskii, Baker & Fabbro 2002 ). Australian populations produce the cyanotoxins cylindrospermopsin and deoxycylindrospermopsin (Hawkins et al. 1997, Saker & Eaglesham 1999). Three morphological forms of R. raciborskii are known from Australia including straight, coiled, and sigmoid/irregular. This morphological plasticity may lead to identification difficulties, as many similarities exist between these morphotypes and other species of Raphidiopsis with terminal heterocytes such as R. philippinensis (Taylor) Anguilera, Berrendero Gómez, Kaštovský, Echenique & Salerno and R. catemaco (Komárková-Legnerová & Tavera) Anguilera, Berrendero Gómez, Kaštovský, Echenique & Salerno. This variability appears intrinsic to R. raciborskii and does not reflect interspecific differences between morphotypes.

SPHAEROSPERMOPSIS

Sphaerospermopsis Zapomělová, Jezberová, Hrouzek, Hisem, Řeháková & Komárková (2010: 415) Type: S. reniformis (Lemmermann) Zapomělová, Jezberová, Hrouzek, Hisem, Řeháková & Komárková (2010: 415)

Filaments planktonic; trichomes solitary, coiled or straight, constricted at the cross walls, with or without mucilaginous sheaths. Apical cells elongated and tapered in straight species, or undifferentiated in coiled species. Vegetative cells spherical or barrel-shaped, compressed during division, with aerotopes. Heterocytes intercalary, solitary, spherical. Akinetes spherical or widely oval, adjacent to either side of the heterocytes.

A widely distributed genus of seven species known from freshwater lakes and reservoirs, rivers and estuaries. Here three species are described from north-eastern Australia. Bibliography: Zapomělová et al. (2009, 2010), Werner et al. (2012), Li et al. (2015, 2016).

1. - 2. - Trichomes straight .............................................................................................................................................. S. aphanizomenoides Trichomes coiled................................................................................................................................................................................2 Coils (7.0–) 8.5–15.8 μm in diameter........................................................................................................................... S. eucompacta Coil diameter 12–24 μm in diameter............................................................................................................................... S. reniformis

Sphaerospermopsis aphanizomenoides (Forti) Zapomělová, Jezberová, Hrouzek, Hisem, Řeháková & Komárková (2010: 415) Fig. 22 A–H .

Basionym: Anabaena aphanizomenoides Forti (1911: 4)

Filaments planktonic; trichomes straight or slightly flexuous, slightly attenuated towards the ends, constricted at the cross walls. Vegetative cells quadrate or sub-spherical, isodiametric or 1–2 × longer than broad, 3.0–6.0 (–10) μm long × 3.0–5.5 (–7.0) μm broad, with aerotopes; apical cells slightly narrowed and shortly rounded or elongated and club-shaped. Heterocytes spherical or ovate, intercalary, solitary, 4.0–7.5 μm in diameter. Akinetes spherical to widely oval, 6.5–14.6 μm long × 6.5–14.0 μm broad, solitary or in pairs, adjacent either side of the heterocytes, epispore smooth, colourless.

Specimens examined:—Atkinson Dam, Beardmore Dam, Bill Gunn Dam, Bjelke-Petersen Dam, Boondooma Dam, Borumba Dam, Bowen R. at Bowen R. Weir, Burdekin Falls Dam, Burnett R. at Ben Anderson Barrage, Burnett R. at Claude Wharton Weir, Burnett R. at Jones Weir, Burnett R. at Kirar Weir, Burnett R. at Ned Churchward Weir, Callide Dam, Cania Dam, Condamine R. at Chinchilla Weir, Coolmunda Dam, Corella Dam, Crookes Dam, Eungella Dam, Fairbairn Dam, Fitzroy R. at Bedford Weir, Fitzroy R. at Bingegang Weir, Fitzroy R. at Eden Bann Weir, Fitzroy R. at Glebe Weir, Fitzroy R. at Moura Weir, Fitzroy R. at Neville Hewitt Weir, Fitzroy R. at Tartrus Weir, Fitzroy R. at Theodore Weir, Fred Haigh Dam, Gattonvale offstream storage, Glen Niven Dam, Glenlyon Dam, Haughton R. at Giru Weir, Horn Is. Dam, Ibis Dam, Julius Dam, Jumna Dam, Kinchant Dam, Kolan R. at Bucca Weir, Lake Clarendon, Leslie Dam, Loudon Dam, Maroon Dam, Mary R. at Mary R. Barrage, Moogerah Dam, Moura offstream storage, Paradise Dam, Peter Faust Dam, Pioneer R. at Dumbleton Weir, Pioneer R. at Marian Weir, Pioneer R. at Mirani Weir, Six Mile Ck at Bajool Weir, Teemburra Dam, Tinaroo Falls Dam, Warrego R. at Allan Tannock Weir, Wuruma Dam, Wyndham Dam.

Other records:— New South Wales: Lake Victoria, Baker (1991), Clarie Hall Res., River Murray at Tocumwal, Humpage et al. (2013); Victoria: River Murray at Torrumbarry, Sullivan et al. (1988), River Murray at Merbein, Baker (1991); South Australia: Lake Alexandrina, Lake Albert, Baker (1991), Ling & Tyler (2000); Western Australia: Vasse R., Lee et al. (2014).

Observations:—Widespread species throughout Australia, known from every mainland state. Australian populations closely resemble European populations (after Hindák 2000). There has been wide variability reported in the vegetative cell dimensions of this species (see Stüken et al. 2009, Zapomĕlová et al. 2009), however the shape and position of akinetes adjacent to the heterocytes is generally a conserved feature.

Figures

FIGURE 20. A–F Raphidiopsis mediterranea; G Raphidiopsis curvata. Scale bars = 20 μm

FIGURE 21. A–H Raphidiopsis raciborskii (arrows indicate position of akinetes). Scale bars = 20 μm

FIGURE 22. A–H Sphaerospermopsis aphanizomenoides. Scale bars = 20 μm