A COMPARATIVE BIOGEOGRAPHICAL STUDY OF MYXOMYCETES IN THE MID-APPALACHIANS OF EASTERN NORTH-AMERICA AND 2 REGIONS OF INDIA

Although species lists for particular localities have been compiled by numerous workers, relatively few biogeographical studies of myxomycetes (plasmodial slime moulds) have been carried out. In the present study, the data represented by a total of 3788 collections of myxomycetes made during the period of 1954-90 from two study areas in the mid-Appalachians of eastern North America and study areas in northwestern and southern India were analysed to obtain information on the biogeographical relationships and patterns of occurrence of these organisms. The climate of the study area in southern India is tropical/subtropical, whereas both study areas in eastern North America and the one in north western India have a temperate climate. Based on coefficient of community indices calculated for all possible combinations of the four different data sets, southern India had the lowest overall similarity (mean index = 0.322) to the other study areas. Members of the Physarales made up a much greater proportion (63%) of the collections from southern India than elsewhere, whereas members of the Liceales were conspicuously under-represented when compared to the other study areas. The majority of collections ( > 63%) from southern India occurred on leaf litter and other types of non-woody plant debris, whereas > 80% of all collections from eastern North America and north western India were made from woody substrates. These results suggest that myxomycetes show recognizable patterns of latitudinal variation not unlike those described for many other groups of organisms. Not only is the assemblage of species found in tropical/subtropical regions of the world distinctly different from that of temperate regions, but the species present also exhibit quite different patterns of distribution with respect to the types of substrates upon which they typically occur.