Staurastrum antarcticum Anissimova & Kutuzova

Anissimova, Olga V. & Kutuzova, Irina A., 2024, Staurastrum antarcticum: a new desmid species from a lake in Oasis Larsemann Hills (East Antarctica), Phytotaxa 644 (3), pp. 236-240 : 238-239

Staurastrum antarcticum Anissimova & Kutuzova , sp. nov. ( Figs. 2–3 )

Diagnosis: —Cells in frontal view about as long as broad, with a rather deep sinus, widely opened from a U-shaped apex. Semicell body in frontal view oblong-subelliptic with broadly rounded angles and about straight apex. Semicells in apical view 3-radiate with slightly concave sides and broadly rounded angles. Cell wall smooth. Cell wall pores concentrated in a circle around the base of the semicell lobes, evenly spaced at a distance of about 2 µm from each other. Zygospores are not known. Dimensions: length 9.6-10.6 μm, breadth 9.8‑11.1 μm, isthmus 4.1‑4.7 μm.

Type:—EAST ANTARCTICA, Oasis Larsemann Hills: LH-59 lake, 69°23’31.00” S, 76°21’8.36” E, epiphyton, I. Kutuzova, 13 February 2023, (holotype: MW!, preserved as a fixed natural sample, depicted in Figs. 2A, B , Algae collection of the Department of Mycology and Algology) .

Distribution and ecology:—The taxon is only known from LH-59 lake in the area of Progress Station (East Antarctica, Oasis Larsemann Hills, Broknes Peninsula). It was found in samples of periphyton, in 2023. The water in the lake had the following characteristics: pH 4.5–5.0, total dissolved solids levels of 81.4–92.1 mg /l,. conductivity of 153–190 µS/cm and temperature 0.8–6.9°С.

The samples contained mainly cyanobacteria and but small numbers of eukaryotic algal taxa. There were some species of small-sized diatoms, two species of desmids ( Cosmarium sp. and C. impressulum Elfving var. alpicola Schmidle (1895: 388)) and a large number of filaments of Mougeotia sp. in a sterile state.

Figures

FIGURE 2. Light microscopical images of Staurastrum antarcticum sp. nov., from Oasis Larsemann Hills (Antarctica). A, C) Vegetative cells in frontal view, B, D) Vegetative cells in apical view. Scale bar = 10 µm.

FIGURE 3. Scanning electron micrographs of four cells of Staurastrum antarcticum sp. nov., illustrating the presence of mucilage pores and mucilage plugs (indicated by arrows) on the cell wall. Scale bar = 2 µm.