Porosira glacialis (Grunow) Jørgensen

Al-Handal, Adil Y., Torstensson, Anders & Wulff, Angela, 2022, Revisiting Potter Cove, King George Island, Antarctica, 12 years later: new observations of marine benthic diatoms, Botanica Marina (Warsaw, Poland) 65 (2), pp. 81-103 : 83

Porosira glacialis (Grunow) Jørgensen ( Figures 2–4 , 107, 108 )

Literature: ( Hendey 1964, p. 88, pl. 1, fig. 12; Scott and Thomas 2005, p. 84, fig. 2.41a–f).

Description: Diameter 54–72 µm.

Remarks: Valve areole very fine, either arranged in fascicules or irregularly scattered, sometimes indistinct. Valve surface with scattered spines. A single labiate process located below valve margin and visible in LM.

Ecology and distribution: This is a marine neritic species widely distributed in both the Arctic and Antarctica (bipolar), normally associated with sea-ice flora. It is also known from temperate waters ( Pike et al. 2009). According to Armand et al. (2005), P. glacialis is found on the sediment only as resting spores. In our material, all specimens were vegetative cells that might have been deposited from the plankton. Frequent in Potter Cove.

Thalassiosira eccentrica (Ehrenberg) Cleve ( Figure 5 ) Literature: ( Fryxell and Hasle 1972, p. 300, figs. 1–18; Hendey 1964: p. 80, pl. 24, fig. 7 [as Coscinodiscus eccentricus Ehrenberg ]; Simonsen 1974, p. 9, pl. 2, figs. 1–3).

Figures

Figures 2–11: Marine benthic diatoms in Potter Cove, King George Island, Antarctica, summer 2015. (2–4) Porosira glacialis. (5) Thalassiosira eccentrica. (6) Thalassiosira gracilis. (7) Thalassiosira oliveriana. (8) Thalassiosira sp. (9, 10) Melosira sol, (10) showing chain of cells in girdle view. (11) Melosira cf. adeliae.

Figures 107–112: SEM images of the marine benthic diatoms in Potter Cove,King George Island, Antarctica,summer 2015.(107,108) Porosira glacialis, internal valve view showing the single marginal labiate process. (109–111) Entopyla ocellata, (109, 110) external valve view showing the wide and superficial apical porefield which occupies large area of valve face, (111) internal valve structure showing the narrow and crescent-like rimoportula openings (white arrows). (112) Navicula sp. 2.