Microchaete Thuret ex Bornet & Flahault (1886)

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

Microchaete Thuret ex Bornet & Flahault (1886)

Type: M. grisea Thuret ex Bornet & Flahault (1887)

Filaments uniseriate, heteropolar, solitary or in small irregular groups, straight or slightly flexuous; attached by the base or creeping along the substratum or unattached and growing freely amongst other algae. Sheaths cylindrical, ± slightly narrowed or widened towards the ends, thin, firm, and usually colourless and unlamellated. False-branching typically lacking, occasionally with tolypotrichoid type false-branching. Trichomes cylindrical along the whole length or slightly attenuated towards the ends. Vegetative cells barrel-shaped to cylindrical, isodiametric or shorter or longer than broad, often shortened and rounded at the apex. Heterocytes basal, spherical to sub-spherical, less frequently intercalary. Akinetes known from a few species, solitary or in short rows adjacent to the trichome apex. Reproduction by the production of hormogonia or akinete germination.

As currently prescribed, the genus Microchaete is polyphyletic ( Hauer et al. 2014). Many species share morphological similarity with species from Calothrix that do not have terminal hairs. Various morphotypes were observed from habitats across north-eastern Australia which do not correspond to currently described species; due to the uncertainty about the genus, three have been given nominal designations here. Bibliography: Komárek (2013), Hauer et al. (2014), Komárek et al. (2014).

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Filaments amongst other algae or attached to rocky substratum........................................................................................................2 Filaments epiphytic on filamentous algae or submerged vegetation..................................................................................................3 Vegetative cells 0.6–1.3 × longer than broad, 5.0–6.5 μm broad........................................................................................... M. sp. A Vegetative cells up to 1.6 × longer than broad, 3.8–5.6 μm broad......................................................................................... M. sp. B Basal heterocytes <6.8 μm broad .......................................................................................................................................... M. sp. C Basal heterocytes> 6.8 μm broad......................................................................................................................................................4 Trichomes 6.0–7.5 μm wide................................................................................................................................................. M. tenera Trichomes 7.7–10.4 μm wide.................................................................................................................................... M. cf. investiens