Myxomycete biodiversity in four different forest types in Costa Rica

The moist chamber culture technique was used to examine patterns of biodive rsity and distribution of myxomycetes in four different forest types in Cos ta Rica, focusing on the substrates represented by the bark surface of livi ng trees and leaf litter. Rarefaction as well as bootstrap analyses were ca rried out to estimate the completeness of the survey in terms of the number s 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 m yxomycetes, species richness was found to be negatively correlated with epi phyte (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 eleva tion. All of these results indicate that the excess of moisture in continuo usly moist tropical forests does not favor myxomycete growth and developmen t. Species richness and frequency patterns for both substrate types were fo und to be comparable with those calculated from a data set reported for a s tudy area in the temperate zone, indicating that myxomycete biodiversity do es not reach its highest levels in tropical forests.