Studies of neotropical mycetozoans

Abstract

During the period of 1995 to 2002, biotic surveys for mycetozoans (slime moulds) were carried out in a number of study areas in Central and South America to document more complete- ly the species associated with tropical forests and other ecosystems in this region of the world. Primary emphasis of these surveys was on myxomycetes; more limited data were obtained for dic- tyostelids and protostelids, two other groups of mycetozoans that share some of the same micro- habitats as myxomycetes. The body of data represented by the more than 8,000 field and moist chamber collections of myxomycetes accumulated during these surveys have provided evidence for a number of ecological patterns not previously reported for myxomycetes. The most important of these are that (1) both overall abundance and species richness of myxomycetes appear to be lower in tropical forests than in temperate forests, (2) species richness and (especially) relative abun- dance increase with decreasing moisture conditions, and (3) in tropical forests, distinct assem- blages of myxomycetes are associated with microhabitats that have no counterparts in temperate forests. The most extensive of the latter is the aerial litter (dead but still attached plant parts) micro- habitat, where myxomycetes appear to be especially abundant and diverse. Most of the dictyostelids recovered from samples collected in the various study areas are cosmopolitan forms or species known to have tropical or subtropical affinities. However one new species (Acytostelium minutis- simum), several other forms that possibly represent undescribed species, and a number of species not previously known from the Neotropics also were recorded. For the most part, the species of pro- tostelids associated with Neotropical forests are the same as those found in temperate regions of the world, and species richness in this group appears to be highest in mesic but not wet habitats. Microhabitat trends of particular species of protostelids appear to vary with habitat. Overall in