Kaszab Zoltán (szerk.): A Magyar Természettudományi Múzeum évkönyve 66. (Budapest 1974)

P. Komáromy, Zs.: Studies on the aerophytic Chorhormidium flaccidum (Kütz.) Fott (Ulotrichales)

ANNALKS Tomus 66. HISTORICO-NATURALES MUSEI NATIONALIS HUNGARICI Budapest 1974. Studies on the Aerophytic Chorhormidium flaccidum (Kiitz.) Fott (Ulotrichales) By Zs. P.—

KOMÁROMY, Budapest Abstract — The diameter ((5.3 — 7.0 \x), the minimum (5.5—8.8 LA) and maximum (22 — 24 LA) length values of Chlor

hormidium flaccidum (KÜTZ.) FOTT filaments in various cultures conditions are the same, and they are identical with the values obtained from crude cultures of different localities under natural conditions. A specific character of the species is that in liquid media the filaments in different physiological states differentiate according to their specific weight. — 5 figures. In the course of the study of the aerophytic alga flora of the Mátra Mts. it was established that soil surface samples collected in early spring and in rainy autumn periods from different localities comparatively distant from each other always included Chlorhormidium FOTT sp. (= Hormidium KÜTZ.). Under laboratory conditions in crude cultures wetted with distilled water the Chlorhormidium sp. formed a continuous layer of silky lustre on the fragments of leaves, perules and lumps of soil, further, it formed a thin film on the surface of water collected at the bottom of the Petry dish or between large lumps of the soil. Under the microscope the filaments forming the superficial film and the thin layer of silky lustre showed no difference in structure. The filaments were not ramose, there was no special form to distinguish thallic or apical cells. Cell wall was thin, weakly mucose. Diameter of filaments is 6.3-7.0 LA, the minimum length of the cell is 5.5 u,, the maximum is 24 \L. The chloroplast is parietal, filling about the half of cell cavity, in it one oval or globular pyrenoid is seen. A nucleus may be seen even without staining, situated in the cytoplasm bridge opposite the chloroplast. Characteristic vacuoles are present at the end of the cell. During the examination reproduction occurred vegetative cell division and by fragmentation of filaments. In the alga layers on the soil surface of the Mátra Mts. the Chlorhormidium species stands close as far as dimensions are concerned to Hormidium flaccidum KÜTZ. described also by B. Petersen (1932, 1935). However, with regard to physiology (in fluid cultures forming a superficial film and in the medium a mass like cotton-wool) it resembles Chlorhormidium flaccidum (KÜTZ.) FOTT examined by TAROOQUI (1969). Chlorhormidium flaccidum has a wide scale of ecological plasticity, it occurs on the barks of trees, on bare soil, litter, stones ans also in water. This explains why several authors described it under various names (FOTT 1960). STRÖM (1928) established by his experiments that the forms of Hormidium of identical cell structure but of different thallus composition when cultured in media of various pH reproduce with diverging intensity and even display morpho-