Kaszab Zoltán (szerk.): A Magyar Természettudományi Múzeum évkönyve 70. (Budapest 1978)

P. Komáromy, Zs.: Scotiella species (Chlorophyceae) and their theoretical life-cycle

illuminated by tubes about 3000 Lux (8 hours per day). The morphological diversity of the cells were observed in these enrichment cultures and some agar-agar cultures were used in studying the life-cycle of the species. The agar-agar cultures were made with Bold liquid medium (1.5% agar-agar). It was not a unialgal culture, but contained three species: Scotiella levicostata HOLLERB., Chlorella fusca SHIHIRA et KRAUSS, and Chlorocloster terrestris PASCH. Results and discussion — The vegetative cells of Sc. levicostata occurring in enrichment cultures were morphologically diverse as well as in dimension. The individuals are of elongated oval shape and provided with 6-8 rather smooth ribs (Plate II: Fig. 1), and they ended in two poles. In the cell content some discoid parietal chloroplasts with one pyrenoid were usually visible, and a considerable amount of the characteristic oil globules were mostly present. There are some other individuals which were on oocystoid appearance. No ribs were observed on these cells, and they were smaller in dimension than the ribbed ones. The chloroplast was parietal with more or less lobed outlines. One prominent pyrenoid was visible in each of the cells. Some intermediate forms were also observable. In some of the enrichment cultures the multiplication of the ribbed as well as the oocystoid cells occurred (Plate II: Figs. 2, 3). It happens by 2 or 4 autospores but in some cases Enallax-l\kc colonies were observable, too (Plate II: Fig. 2). Some aged cells were found in the cultures (Plate II: Fig. 4). The ribs were wing-like on these individuals and large oil globules and some parietal chloroplast were demonstrable in the cell content. Pyrenoid was present or absent. The lifecycle of the species was investigated in Bold agar-agar culture. I observed that Sc. levicostata had a long life-cycle, because I could not observe any multiplication on the 17th day after inoculation, while Chlorella fusca have multiplied three or four times. The growth of the Scotiella cells were fairly slow, so the reproduction stage was demonstrated in a one-monthold culture. Five phenophases (KOMÁROMY 1976, SZUJKÓ-LACZA et al. 1976) were distinguishable in the vegetative stage of Sc. levicostata as follows: The young vegetative cells are spindlelike, 5-7 /urn in diameter, 10-12 fj,m long. No ribs were observable, the chloroplast is a parietal sheet with a pyrenoid (Plate II: Fig. 5a). The adult cells are oval, 5-9 [xm wide and 9-13 /urn long in optical section. The ribs are prominent, their number were determined as six or eight in individuals, and they ended in two projecting poles. The chloroplast divided up and some oil globules were visible in the cell-content. A pyrenoid is present (Plate II: Figs. 5b-c). Before multiplication the individuals are wide oval, 8-11 ^m wide and 12-15 long. The ribs are well visible, but the poles are not so projecting. There are some chloroplasts with undefined outlines. Pyrenoid is present, and large oil globules fill up the cell cavity (Plate II: Fig. 5d). In the succeeding phase the cells lost their former outer appearance, the cell wall became smooth, the outline of the chloroplasts and the pyrenoid were difficult to observe. The whole of the cell content is granular. These individuals are 8-11 ^m wide and 12-14 ton long (Plate II: Fig 5e). In the last phase autospores were developed. The cell walls of the daughter cells are thin, with fine ribs. The cell content is granular, unformed. The young cells, assumed their characteristic appearance later (Plate II: Fig. 5f, Plate III: Fig. 3). There are two or four daughter cells in one autosporangium. The autospores are 7-8 [im wide and 9-10 /urn long. In some cases an Enallax-Xikç, phase was observed in the enrichment cultures. The order of the daughter cells, the form of parietal chloroplast, the light green colour of cells, the absence of oil globules and the ribs of cell wall were similar to Enallax. Therefore, the original description of Enallax genus, erected by PASCHER (1943) was closely examined. According to PASCHER "Die Membranfalten zeigen bei Scotiella wie bei Enallax eine bestimmte Form und bestimmte Anordnung" ... "Enallax stellt die kojoniale Weiterentwicklung der einzeln lebenden Scotiella dar." (I.e. p. 188). Later PASCHER