Ewamiania thermalis G.B. McGregor & B.C. Sendall (2017: 46)

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

Ewamiania thermalis G.B. McGregor & B.C. Sendall (2017: 46) Figs. 68 A–K, 69 A–C .

Filaments densely arranged to form blackish-green hemispherical caespitose mats beginning as small 1–4 cm diameter circular tufts up to mats 4–6 cm wide by several metres long. Filaments isopolar, cylindrical, straight or flexuous, 15.5– 40 μm in diameter, densely arranged and erect, often parallely fasciculate, up to 3 cm long, with tolypotrichoid false-branching, rarely with scytonematoid false-branching. Vegetative cells short barrel-shaped or isodiametric, 0.5–1.2 × as long as wide, 7.2–16.9 μm long, 10.4–14.5 μm wide, slightly constricted at the cross walls, with granulated contents; terminal cells widely rounded. Sheath firm, relatively thick, lamellated, uncoloured to yellowish or yellow–brown in colour, cylindrical, closed at the apex. Heterocytes basal and intercalary, solitary, rarely up to 2(3) in series, developing particularly at the base of branches, spherical or ovoid, 7.5–16.5 μm in diameter, 9.0–24.6 μm long. Akinetes not observed. Reproduction by up to 12-celled hormogonia, often with terminal heterocytes, not constricted at cross-walls, separated by necridic cells.

Specimens examined:—Talaroo thermal springs.

Observations:—A subaerophytic species known from a thermal spring complex in tropical, north-eastern Australia. Observed growing along the crests of travertine minidams just above the thermal waters discharging from the springs (48.5–62.7 oC) as well as along some of the shallow unconfined areas of vent-discharge aprons.

ININGAINEMA

Figures

FIGURE 69. A–C Colonies of Ewamiania thermalis growing along the crests of minidams just above the thermal waters discharging from the springs.