Wollea saccata Bornet & Flahault (1886: 233)

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

Wollea saccata Bornet & Flahault (1886: 233) Fig. 54 D .

Thallus macroscopic, cylindrical, finger-like, mucilaginous, up to 10 cm long × 2–10 mm wide, comprised of ± parallel arranged trichomes. Trichomes cylindrical, clearly constricted at the cross walls, not or slightly attenuated towards the apices. Vegetative cells barrel-shaped, isodiametric to longer than broad, or elongate-cylindrical with rounded ends, blue-green in colour, 5–10 μm long × 4–6 μm wide; apical cells rounded. Heterocytes spherically ellipsoidal to cylindrical, slightly broader than vegetative cells, 6.5–10 μm long × 4–6 μm wide. Akinetes elongate-ellipsoidal to ovate, 3–5 in series, either side of the heterocyte, 15–22 μm long × 6–8 μm broad, with smooth exospore.

Specimens examined:—Thompson R. at Longreach.

Observations:—Growing on silty substrate in the shallow littoral zone of a subtropical riverine waterhole in small colonial clumps. Known from Europe and North America (Komárek 2013).

5. RIVULARIACEAE

Rivulariaceae Bornet & Flahault (1886: 338)

Type: Rivularia C.Agardh ex Bornet & Flahault (1886: 345)

Thallus macroscopic, usually attached to the substratum, flat, prostrate, crustaceous, bushy or gelatinous, spherical, ± encrusted, rarely occurring as solitary filaments. Filaments heteropolar, uniseriate, apical parts typically ending in terminal hair-like cells, constricted or unconstricted at the cross walls. Filaments with gelatinous sheaths, in some genera stratified at the ends and funnel-like widened, sometimes laterally confluent. Branching occurs in some genera; where present occurring as single false-branching, less typically geminate; branches grow in the same direction as the main filament. Vegetative cells cylindrical or barrel-shaped, terminal cells often elongated, narrowed and cylindrical. Heterocytes basal, sometimes intercalary, single or up to several in series.Akinetes known from several genera, usually developing above the basal heterocytes, solitary or in series. Reproduction by thallus disintegration, through branching, or production of hormogonia.

A cosmopolitan family of seven genera, five of which are known from Australia; four are described here from north-eastern Australia.

Figures

FIGURE 54. A–C Wollea ambigua; D Colonies of Wollea saccata; Colonies of Nostoc verrucosum. Scale bars = 20 μm