Rivularia beccariana Bornet & Flahault (1886: 356)

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

Rivularia beccariana Bornet & Flahault (1886: 356) Fig. 67 A–F.

Colonies small, irregularly hemispherical up to 1 cm in diameter, without calcareous encrustations, olive- to blue-green in colour. Sheaths thin, colourless or yellow-brown, sometimes indistinctly lamellated, narrowed towards the ends. Trichomes gradually attenuated towards the end, not or slightly constricted at the cross walls, attenuated into a long flexuous hair at the trichome apex. Vegetative cells cylindrical or long barrel-shaped, isodiametric or longer or shorter than broad 8.0–19.0 μm long × 4.8–6.5 μm broad. Heterocytes spherical, solitary, 7.2–9.5 (–14) μm in diameter.

Specimens observed:—Fitzroy R. at Murray Lagoon.

Other records:— Queensland: SE Queensland, McLeod (1975), Stony Ck, Wallaman Falls Natl Park, A.B. Cribb, 1972 ( BRI 0702310 ) ; New South Wales: Northern Tablelands , Severn R., Dundee, on Vallisneria, Skinner, 2000 ( NSW) . Central Coast, Dismal Swamp , Wollemi Natl Park, on Myriophyllum leaves, Coveny, 2000 ( NSW) . Victoria: Dandenong area, Devilbend Res., south of Mornington , Mackey, 1991 ( MEL 2028556 and 2047042) . Northern Territory: Nitmiluk Natl Park, Seventeen Mile Ck, near crossing on track from Katherine Gorge to Edith Falls , Entwisle, 1997 ( MEL) .

Observations:—Growing amongst littoral vegetation, and filamentous algae; widespread distribution, this epiphytic species, known from a variety of substrates (Komárek 2013), can be cryptic and is therefore likely to be under reported.

Other species known from Australia: R. borealis ( Entwisle 1994) , Victoria; R. calcarea ( Entwisle 1994, Hardy 1906); R. concentrica Pambula R., Chalkhills Rd , off Wyndham–Pambula Rd, 8 km WNW of Pambula, New South Wales, Entwisle, 1991 (MEL), Wallagaraugh R., Newtons Crossing, picnic area, Allan Brooke Rd, New South Wales, Entwisle 1991 (MEL),Adams R above Adams Falls, Strathgordon, Tasmania, Entwisle, 1996 (MEL), Lisdillon Rivulet, Orford–Swansea Rd, 20 km from Swansea, Tasmania, Entwisle, 1996 (MEL).

6. SCYTONEMATACEAE

Scytonemataceae Rabenhorst ex Bornet & Flahault (1886: 85)

Type: Scytonema Agardh ex Bornet & Flahault (1886: 85)

Heterocystous, uniseriate, filamentous, with obligatory false branching. Thallus prostrate, forming flat or woolly mats, sometimes occurring as solitary filaments amongst other algae. Trichomes monoseriate, isopolar, cylindrical or widened or narrowed at both ends, rarely forming hairs, usually with distinct meristematic zone, less frequently combined with intercalary growth. Sheaths usually thick, firm or gelatinous, often lamellated, sometimes funnel-like and widened at the ends, colourless or variously coloured. Heterocytes intercalary, mostly occurring singly. Akinetes absent. Reproduction by the formation of hormogonia.