Cosmarium sp.

Komarzewska, Katarzyna & Kowalski, Wojciech W. A., 2024, Staurastrum cyclacanthum var. pseudobrevissimus - a new variety of desmids and some other rare taxa found in peat bogs (Western Pomerania, Poland), Annales Universitatis Paedagogicae Cracoviensis Studia Naturae 9, pp. 9-32 : 21-22

¬ Cosmarium sp. Fig. 8P–S – Appendix 1

In the plankton materials of peat cut water No. 2, an unidentified taxon from the order Desmidiales belonging to the genus Cosmarium was found. The taxon occurred in near-surface waters on various research dates, both in 2005 and 2006.

Description: The cells are small in size, oval in shape, viewed from the front. Cell wall structure with two types of ornamentation. In the central part, semi-cells are made of 4 oval granules, not connected to each other, forming a bulge. The remaining surface is covered with regularly arranged round granules. Cell length 17.0 µm, width 15.3 µm. The length-to-width ratio is 1.11×. The thickness in the top and side view 1.45 µm. Ellipsoidal semi-cells with rounded sides. The apical part is flat to slightly convex, forming a bulge separated from the main surface of the half-cells by shallow sinus indentations. Isthmus narrow, 3.4 µm wide, open, regularly U-shaped in the inner part. Sinus in the side view of the half-cell, obtuse, open and rounded in the inner part. There is an angular bulge on the sides of each half-cell. In the gable view, the semi-cells are oval, regularly rounded at the ends, widening in the central part and equipped with an angular protruding central ornamentation.

Found in site: The recorded ecological and hydrochemical parameters of the Cosmarium sp. habitat for individual research dates are given in table 4.

In available literature (West et G.S. West, 1908, 1912; Hirano, 1957/III, 1957/IV; Lennzenwger, 1999; Coesel, 1991; Coesel, Meesters, 2007; Palmar-Mordvintseva, 1982, 2005; Croasdale, 1988 and Floristic Desmidia studies), such a form was not recommended taxon, which would correspond to the morphology of its cell. For a comparative analysis of the found cell, illustrations included in the materials of the icon library of the Institute of Botany of the Polish Academy of Sciences in Krakow were also used.

Figures

Fig. 8. L–T. L–O. Staurastrum cyclacanthum var. pseudobrevissimum: L–M. cell ornamentation – view of the apical side, N–O. ornamentation of the front side of the cell; P–S. Cosmarium sp.: P – z ornamentation on the front side of the cell, R. side view (without ornamentation), S. view of the gable side (without ornamentation) (orig. engravings W. W. A. Kowalski)