Myxomycete biodiversity in four different forest types in Costa Rica

The moist chamber culture technique was used to examine patterns of biodiversity and distribution of myxomycetes in four different forest types in Costa Rica, focusing on the substrates represented by the bark surface of living trees and leaf litter. Rarefaction as well as bootstrap analyses were carried out to estimate the completeness of the survey in terms of the numbers of species of myxomycetes present. Both species diversity and myxomycete abundance decreased with increasing elevation and resulting higher moisture levels of the investigated forest types. The two seasonal dry forest types accounted for 90% of the total myxomycete diversity. For bark-inhabiting myxomycetes, species richness was found to be negatively correlated with epiphyte (i.e., mosses, liverworts, and lichens) coverage. For both litter and bark, a higher substrate pH tended to be positively correlated with higher species diversity. Among litter-inhabiting myxomycetes, the proportion of species with rather robust phaneroplasmodia increased with increasing elevation. All of these results indicate that the excess of moisture in continuously moist tropical forests does not favor myxomycete growth and development. Species richness and frequency patterns for both substrate types were found to be comparable with those calculated from a data set reported for a study area in the temperate zone, indicating that myxomycete biodiversity does not reach its highest levels in tropical forests.