Assessment of myxomycete species diversity on twig litter on Yakushima Island, World Natural Heritage site, Japan

Our knowledge of the ecological features of myxomycetes of the Yakushima Island World Natural Heritage site is poor. The present study assessed myxomycetes living on twig litter in Yakushima Island using the moist chamber culture method and focused on their distribution and association with different forest types. The survey was conducted along an altitudinal gradient from the coast to the montane forest (1,360 m). Fallen twigs were sampled from the forest floor surface beneath representative dominant tree species at each survey site. Nineteen twig samples from seven tree species were cultured in dishes for a total of 380 cultures, of which 54% culture dishes yielded myxomycete fruiting colonies. In total, 35 myxomycete species in 15 genera were identified from 19 myxomycete communities. Ordination using non-metric multidimensional scaling indicated a significant correlation between community structure and twig pH. Four different forest types classified according to elevation separated into different myxomycete community structures, with species richness and abundance decreasing with increasing elevation. Species diversity was the highest in the coastal subtropical vegetation community, while the montane forest that comprised Cryptomeria japonica trees had lower species diversity. Subtropical vegetation characteristically involved four species, Comatricha tenerrima, Lamproderma scintillans, Perichaena depressa, and P. chrysosperma, but Cribraria microcarpa preferentially occurred in the montane forests. The dominant trees in the forests apparently affected the myxomycete communities on twig litter. The new distribution data generated through this study provide a better understanding of the spatial composition of myxomycetes on Yakushima Island.