Geographical Distribution of Acrasieae

SUMMARYThe frequency of occurrence of Acrasieae was determined in 28 temperate and tropical countries on five continents. Twenty-nine different cellular slime molds, including five new to science, were isolated. Diversity is greatest in the tropics and decreases as latitude increases. Eight species are cosmopolitan. The 11 species found in temperate forest also occur in the tropics; no endemics to temperate areas have been found. Half the species are endemic to the tropics and subtropics but the majority of these are pantropical. On the basis of frequency distributions six cosmopolitan species show definite responses to a climatically controlled temperature gradient. Two other cosmopolitan species Dictyostelium mucoroides and Polysphondylium pallidum are relatively unresponsive to climate or vegetation. The responses to a climatic temperature gradient may be direct but more likely are related to substrate.