Substrate assemblages of Myxomycetes (Myxogastria) on the bark of living trees and aerial litter in Vietnamese forests

Abstract

Myxomycete (Myxogastria) are amoeboid protists, usually associated with soil or nearby substrates, as their trophic stages require moist conditions and sufficient number of microorganisms to feed on. However, they are able to inhabit places that have no direct connection with soil. In this paper myxomycete assemblages encountered on bark and aerial liter, a unique substrate of tropical forest, were studied. The material was collected in different years in various vegetation types of 3 national parks, Phia Oac-Phia Den, Bidoup-Nui Ba and Cat Tien, located in distant parts of Vietnam during the last 10 years. Taxonomic diversity was revealed via the experiment using moist chamber cultures. A total of 1009 cultures resulted in 747 records, assigned to 87 morphospecies from 5 orders, 9 families, and 23 genera. Seventy-three species were recorded on the bark of living plants and 45 were found on aerial litter, and the study for each substrate was completed for 74.5 and 72.7 per cent respectively. More than a half of the total number of species was presented by singletons and doubletons. The analysis of indicator species was performed, which confirmed the dominance of specialist species on bark (Cribraria confusa, C. minutissima, and Licea operculata) and aerial litter (Perichaena depressa, P. dictyonema, and P. pedata). Some species, such as Perichaena chrysosperma, demonstrated no specific substrate preference. A typical lignicolous species in temperate regions, Stemonitis fusca, appeared to be abundant on aerial litter, showing a change in substrate preferences, which is common for several myxomycete species in tropics. High-quality photographs, including those obtained with SEM, of 10 indicator morphospecies are provided.