Kaszab Zoltán (szerk.): A Magyar Természettudományi Múzeum évkönyve 63. (Budapest 1971)
Gönczöl, J.: Aquatic Hyphomycetes from the Mts. Börzsöny
Tetracladium marehalianum DE WILD (Table II, Fig. 2) According to INGOLD (1966), this species is very frequent in Great Britain, T. setigerum common, while T. maxilliformis rare. In the course of my investigations of the Morgó brook, I failed to discover T. maxilliformis (found by BÁNHEGYI in Hungary, 1962), T. setigerum appeared to be very rare, while the frequency of T. marehalianum fluctuated between very wide limits during the year, its abundance in the lower and rarity in the upper reaches of the stream were the most conspicuous among those of all aquatic Hyphomycetes. According to the investigations up to now, the seasonal distribution was as follows : in the January sample, of very rich material both as to species and individual numbers, T. marehalianum occurred very rarely, in no more than one-tenth percent of all conidia. The February and March samples showed ratios similar to that of January. The number of conidia became higher first in the first days of May (12%), and since then T. marchalianus appeared in masses, the most frequent species for every month until October —November (60—70% of all conidia in August). Interestingly, changes in the frequency of Alatospora acuminata displayes an exactly opposite trend during the year. Concerning the comparative investigations, the individual numbers of T. marehalianum was the highest in June and July in the lower reach: 55 and 64%, respectively, while in the upper reach merely 0.3—0.4%, with no conidia found in August. In June, the temperature of the brook-water differed significantly at the two sample sites: at site I 18 °C and at site II 13—14 °C. This difference disappeared by August, and I found a uniform 15—16 °C water temperature along the whole course of the brook. Even the total number of spores was smaller at the upper reach, whereas the lower one was rich in the conidia of also the rarer species. Proportional occurrence of some conidia in the foam Species Anguillospora sp. Clauariopsis aquatica DE WILD Lemonniera aquatica DE WILD Tricladium splendens INGOLD Differences were found also in the developmental stage of the conidia: in the upper reach nearly all conidia were germinating whereas none of them was germinating in the lower reach. Tetracladium setigerum (GROVE) INGOLD (Table II, Fig. 1) One or two specimens of its conidia were found in the lower reach at all seasons of the year. It was only comparatively rarer in the winter —-early spring samples. ver reach Upper reach 1 10 1 20 1 10 1 20 5 TT. Múzeum Évkönyve 1971
