Stigonema ocellatum Thuret ex Bornet & Flahault (1886: 69)

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

Stigonema ocellatum Thuret ex Bornet & Flahault (1886: 69) Figs. 84 A–D , 85 A–E.

Filaments solitary, growing amongst other algae or aquatic plants, forming cushion-like clusters or tufts, olive-green to brownish in colour, 18–35 (–50) μm broad, irregularly branched. Branches long, flexuous, generally of the same wide as the main filament; hormogonia occur at the ends of branches; sheath wide, yellow or yellow-brown in colour, slightly lamellated, up to 15 μm wide. Vegetative cells quadrate-globose or globose, 6–24 (–35) μm, blue-green to olive-green in colour, often with colourless to brownish coloured distinct individual envelopes; hormogonia cells short barrel-shaped, 8–15 μm long × 6–12 μm broad. Heterocytes intercalary, lateral, 10–24 μm in diameter.

Specimens examined:—Amity Swamp, North Stradbroke Is., Coomera R. at Lamington Natl Park, Burra Burra Section, Honey Eater L., Moreton Is. Natl Park, Moon Point Fens at Great Sandy Natl Park, Fraser Is. Section, Rainbow Beach Fens, Great Sandy Natl Park, Cooloola Section, Welsby Lagoon, North Stradbroke Is.

Other records:— Queensland: Canal Ck at Twin Falls, Cape York, A.B. Cribb, 1992 (BRI 0714696), Burster Ck, Cape York, A.B. Cribb, 1985 (BRI 0703551), Amiens, A.B. Cribb, 1972 (BRI 0703549), L. Broadwater, A.B. Cribb, 1985 (BRI 0703550), South Mimosa Ck, Blackdown Tablelands,A.B. Cribb, 1985 (BRI 0703554), Upper Kroombit Ck, Kroombit Tops, A.B. Cribb, 1986 (BRI 0703557), Sundown Natl Park, A.B. Cribb, 1985 (BRI 0703559), Missionary Bay, A.B. Cribb, 1979 (BRI 0703560), Refuge Bay, Scawfell Is., A.B. Cribb, 1994 (BRI 0715669); New South Wales: Swampy Plains R. above L. Cootapatamba, H. Steinmann, 1978 (CBG 7806032), Round Mountain Rd, near Barokee Rest Area, Cathedral Rocks Natl Park, Skinner, 2000 (NSW); Oakey R., Cathedral Rocks Natl Park, Cherry (Skinner 0174), 2000 (NSW), Quarantine Stn, North Head, Sydney Harbour Natl Park, Skinner, 2000 (NSW); Woronora R., Heathcote, Hamilton & Lucas, 1915 (NSW A2157–2160), Gadara Ck, Bilpin, Cherry, 1999 (NSW); Tomah Spur, Cherry, 2000 (NSW).

Observations:—Cosmopolitan species; recorded growing in the metaphyton of peaty wetlands, and from the littoral zone of wallum lakes and streams, amongst submerged vegetation (Komárek 2013). This is consistent with observations from similar temperate and tropical biotopes. Records from granitic substrates and the splash zone of cool, subtropical streams in New South Wales may refer to another species.

Other species known from Australia: Queensland: Stigonema minutum, Ling & Tyler (2000)

8. SYMPHONEMATACEAE

Symphyonemataceae Hoffmann, Komárek & Kaštovský (2005:109)

Type: Symphyonema Jao (1944: 75)

Thallose, irregular, flat to pulvinate; filamentous, with true branching; Sheath thin or thick, firm, or widened and mucilaginous, gelatinous, homogeneous or lamellated, colourless or yellow-brown in colour. Trichomes uniseriate, heteropolar or isopolar, not or distinctly constricted at the cross walls, with cylindrical or attenuated branches. Branching reverse Y-shaped, less commonly lateral T-like or V-like; branches usually of the same morphology as the main trichome or narrowed towards the apices. Vegetative cells barrel-shaped, irregularly barrel-shaped or cylindrical; apical cells usually rounded, rarely attenuated. Heterocytes usually solitary, intercalary, barrel-shaped to elongatedcylindrical. Reproduction by disintegration of thallus or in a few species, by production of hormogonia from the filament apices.

SYMPHYONEMA

Symphyonema Jao (1944: 75)

Type: S. sinense C.-C.Jao (1944: 81)

Thallose; thallus pulvinate or woolly, up to 1.5 cm thick, greyish blue with multiple densely coiled, or parallel arranged filaments, sometimes joined into erect fascicles. Filaments irregularly branched, not distinctly morphologically diversified in basal sections and branches. Trichomes uniseriate, isopolar, with vegetative cells usually longer than wide, cylindrical, not constricted or slightly constricted at cross walls, not attenuated towards the ends, with rounded terminal cells. Branching of two types, true or reverse Y-type, and false, scytonematoid; branching initiates remote from the heterocytes (reverse Y-branching originates always from special oblong cells, located between two shortened cells, containing densely granular and deeply coloured contents; later the oblong cell lengthwise divides and new cells elongate). Sheaths firm, homogeneous or slightly lamellated, yellow-brown in colour in mature parts. Vegetative cells blue-green in colour with slightly granular content. Heterocytes intercalary, cylindrical, solitary. Akinetes not observed. Cell division crosswise to the trichome length. Reproduction by hormogonia, separating from trichome apices.

A small genus with two species currently taxonomically accepted; one epilithic species from limestone caves in Spain, and one aerophytic species known from French Guiana. Two strains of Symphonema were isolated from soil in Papua New Guinea and sequenced by Gugger & Hoffmann (2004), which supports the distinct phylogenetic position of this genus. This genus has not been previously described from Australian freshwaters. One new species is described here from north-eastern Australia. Bibliography: Gugger & Hoffmann (2004), Komárek (2013), Komárek et al. (2014).

Figures

FIGURE 84. A–D Stigonema ocellatum. Scale bars = A–C 20 μm, D 50 μm