Kaszab Zoltán (szerk.): A Magyar Természettudományi Múzeum évkönyve 64. (Budapest 1972)

Kol, E.: Snow algae from Signy Island (South Orkney Islands, Antarctica)

In the snow of Signy Island, it was present in several developmental stages in Sample B. The dimensions of the Antarctic plant slightly differ from those of the Northern Hemisphere, the specimens deriving from Signy Island being slightly bigger. This small cryobiont Desmidiaeea is not rare on the snow and glacier surfaces of the Northern Hemisphere, indeed, on one observed occasion it was an important member of the purple-brown ice of the Columbia glacier in Alaska (KOL, 1968). I found it on several snow and ice surfaces of Greenland, Europe and North America. Raphidonema antarctica sp. n. (Pl. I. Figs. 4-7, 10-30, Plate II. Fig. 2) Fuis varie flexuosis, simplex, apicibus setiformibus, 2-4 p latis. Filis 8-16-32 cellulis compositis. Chromatophora singula, parietalia, laminaeformis, viridis, pyrenoidibus et amylio carentia. Multiplicatio aut bipartitione vegetativa transversali {Horum, aut per Sporas. Sporne globosae 3 p in diam. Proximum adest ad Paphidonema nivale LAGERH., sed differt ab eo: 1. flexu filamentorum, 2. latitudine et longitudinefilamentorum, 3. numéros cellidarum, 4. modo multiplication^. Habitat in nive viride Insula Signy, Antarcticum. Masses o funbranching, multiply sinuous or helically curved 2-4 p wide filaments consisting of 8-16-32 cells (Pl. I. Figs. 10-18, Pl. II. Fig. 2). Cells cylindrical. Two end-cells of füament pointed. Chloroplast lamelliform, without pyrenoid. Reproduction by cell-division and spores, that of filaments by transverse division. One of the reproductive processes starts by a 3 p wide sphaerical spore (Pl. I. Fig. 19) slightly elongating (Pl. I. Fig. 21), then curving into a crescent-shape (Pl. I. Fig. 21-22), followed by the appearance of a septum and the elongation of the two young cells (Pl. I. Figs. 23, 24, 26). Cell division continues to form a fourcelled filament (Pl. I. Fig. 25), whose end-cells are still rounded, becoming pointed only later. Division continues until 8-16-32-celled filaments occur. The reproduction of the filaments follows a bisecting process, so that the filament divides, usually between the cells divisible by two or four, by the adjoining surfaces of two cells rounding off and the filament falls apart. This process usually occurs along the curved surface of the filament. One of the ultimate cells of the two filament parts is acute, the other rounded, until also this latter tapers to a point (Pl. I. Figs. 6, 27-29, Pl. II. Fig. 2). This method of division is characteristic to Raphidonema brevirostre SCHERFFEL, hence I call it brevirostre-ty-pe of filamentdivision. In Raphidonema nivale LAGRH., the apical cells of the two young filaments attenuate prior to the separation of the filaments (Pl. I. Fig. 5), and they separate only afterwards ; both apical cells of the young filaments are therefore mucronate already at the time of their separation (Pl. I. Fig. 4) ; I designate this type of filamentdivision as the nivale-ty-pe. Raphidonema nivale LAGERH. was first described by LAGERHEIM (1892) from the red snow of the volcano Pichincha in South America (Ecuador). Since then it was found in the snow of several other regions. It is one of the furthest ranging cyrobiont algal species. Raphidonema antarctica stands nearest to R. nivale LAGERH., differing by 1. the