Coleodesmium Borzì ex Geitler (1942: 154)

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

Coleodesmium Borzì ex Geitler (1942: 154)

Type: C. wrangelii Borzì ex Geitler (1942: 356)

Filaments solitary or fasciculated, forming small irregular mats, shrub-like colonies or tufts on the substratum, heteropolar with obligatory false branching; branching typically initiated by trichome disintegration, lateral branches fan-like and remain parallel attached to the mother filament growing in a common sheath. Mucilaginous sheath colourless or yellow-brown in colour, often lamellated and containing 2–16 parallely arranged filaments which often have their own, laterally coalescent sheaths. Trichomes cylindrical, sometimes slightly narrowed at the base, constricted or unconstricted, constrictions usually more prevalent at the apical ends of the trichome. Vegetative cells cylindrical or barrel-shaped, terminal cells often hyaline and pseudo-vacuolated. Heterocytes basal, hemispherical, oval, ovoid or cylindrical with rounded ends, typically solitary, less frequently in series of 2–3. Akinetes not known. Reproduction by trichome disintegration through the formation of necridic cells, and horomocyte production from the apical regions.

Nine species described, most as epiphytes on aquatic plants or epilithic on boulders and stones in high altitude rivers and streams. Here one species is described from north-eastern Australia, one other species is known from elsewhere in Australia. Bibliography: Dutt et al. (1982), Komárek & Watanabe (1990), Elster et al. (1997), Skinner & Entwistle (2001), Flechtner et al. (2002).