Myxomycetes in Araucaria forests: diversity and community structure across substrate types

Myxomycetes occupy a wide range of microhabitats in forest ecosystems, but substrate-associated ecological patterns remain poorly understood in subtropical Araucaria forests. We investigated myxomycete diversity and community structure across five substrate types in the São Francisco de Paula National Forest, southern Brazil. Dead logs, dead branches, twigs, leaf litter, and living plants were surveyed at three spatially distinct sampling points, resulting in 15 sampling units and three spatial replicates per substrate type. A total of 160 specimens representing 30 taxa, 21 genera, and eight families were recorded. Lycogala exiguum and Tubifera ferruginosa are newly recorded for Rio Grande do Sul. Exact permutation-based Friedman tests detected significant differences among substrate types in species richness ( p = 0.0075), abundance ( p = 0.0060), Shannon diversity ( p = 0.0090), and Simpson diversity ( p = 0.0090), with dead logs showing the highest mean richness and abundance. Community composition also differed significantly among substrates (Bray–Curtis PERMANOVA: pseudo- F ₄,₁₀ = 4.76, R 2 = 0.656, p < 0.001), whereas multivariate dispersion did not differ significantly. These results reveal substrate-associated variation in myxomycete diversity and community composition within the sampled forest. However, given the limited spatial and temporal sampling and the lack of quantitative measurements of substrate availability, these patterns should be interpreted at the local scale.