B. Papp szerk.: Studia Botanica Hungarica 29. 1998 (Budapest, 1999)

Gönczöl, János; Révay, Ágnes: Aquatic Hyphomycetes in a tributary of the Morgó stream, Börzsöny Mts, NE Hungary

sumption that low altitudes and/or hardwater may be preferred habitats by this species (ROSSET and BÄRLOCHER 1985, CHAUVET 1991). At the same time Tetracladium marchalianum classified also as a species typical in hardwater (ROSSET and BÄRLOCHER 1985) and/or in lowland streams (CHAUVET 1991) occurred only with very low proportion in the conidial communities throughout the year. This finding is a further contribution to the knowledge of the spatial distribution of this species. Considering both the altitude (190 m) and the chemical character of the stream at Site Cs a higher occurrence of T. marchalianum would be expected. An explanation for the limited role of T. marchalianum at this site may be in connection with the absence of alder (Alnus glutinosa) and the dominance of beech (Fagus sylvatica) in the riparian vegetation. Co-occurrence of T. marchalianum and alder leaf substratum have been pointed out in several streams in Hungary (GÖNCZÖL and RÉVAY 1992). Because of the spatial closeness of the downstream sites of the Morgó stream where Clavatospora tentacula is a consistent species in the summer and early autumn conidial communities (GÖNCZÖL 1971, 1975, GÖNCZÖL et al. 1999) its absence at Site Cs in the Csömöle stream was striking. The influence of the annual temperature range, being more limited than that of the Morgó stream, can be suspected as one of the reasons for the different patterns of the distribution of C. tentacula. The hardly detectable presence of Tetrachaetum elegáns and Tumularia tuherculata, might be explained with the unfavourable chemical character of this stream. Both species are considered as typical in softwater streams (BÄRLOCHER and ROSSET 1981, GÖNCZÖL 1987). Amongst the species with scolecoid conidia Filosporella sp. and Anguillospora sp. 1 were permanently present with high percentage distribution in most of the samples. Filosporella sp., a widely distributed species in the downstream portion of the Morgó stream (as Filosporella sp. 1 in GÖNCZÖL et al. 1999), appeared with extremely high proportions in summer and early autumn samples at Site Cs. The conidia of Anguillospora sp. 1 have been collected several times from hardwater streams in Aggtelek Mts (GÖNCZÖL and RÉVAY 1992) and this species was pointed out as a late colonist on submerged wood immersed at hardwater portion of the Morgó stream (RÉVAY and GÖNCZÖL 1990, GÖNCZÖL and RÉVAY 1993). The identification of these two important species is warranted both in taxonomic and ecological respect. * * * Acknowledgement. This study was supported by a grant from the Hungarian Scientific Research Fund (OTKA No.T-17581).