AQUATIC HYPHOMYCETE DISTRIBUTION IN SOUTH-WESTERN FRANCE

In a survey of aquatic hyphomycetes in South-Western France, the species composition of conidia in foam samples was analysed at twenty-seven stations located on different streams. Correspondence analysis was used to examine the relationships between general distribution patterns of the hyphomycete species and some external factors (altitude, pH, temperature, and season). With respect to the first two axes determined, a group of five species (Campylospora chaetocladia Ranzoni, Campylospora sp., Heliscus tentaculus Umphlett, Lunulospora curvula Ingold and Triscelophorus monosporus Ingold) emerged and was clearly associated with typical lowland streams with high pH and temperature. In a second analysis, in which these five species and nineteen rare species were excluded, two species (Clavatospora longibrachiata (Ingold) Marvanova and S. Nilsson and Tetrachaetum elegans Ingold) appeared characteristic of acid water (pH < 6), low altitude and autumn months. Many of the remaining species were essentially discriminated in relation to altitude. Tetracladium marchalianum de Wildeman, Tricladium angulatum Ingold and Tricladium gracile Ingold were typical of lowland streams, whereas Taeniospora gracilis Marvanova and Tricladium chaetocladium Ingold were generally found in mountain streams. Compared to the effect of altitude, water pH seemed to be of secondary importance in this region.