Lichen thalli as substrates and microhabitats for slime moulds (Myxomycetes)

Lichen thalli and plasmodial slime moulds often co-occur in cryptogam-rich microsites on bark, decaying wood and soil, where they form part of complex forest microhabitat systems. This evidence-led synthesis compiles published observations of myxomycete sporocarps developing on lichen thalli, together with evidence for trophic stages within thallus microzones and environmental studies describing lichen–myxomycete co-occurrence under shared abiotic drivers. The assembled evidence indicates that lichen thalli repeatedly act as microtopographically heterogeneous fruiting substrates, potentially linked to surface roughness and associated microbial films, and can harbour myxomycete trophic stages, whereas direct evidence of feeding on lichen symbionts is absent. Licea parasitica (Zukal) G.W. Martin is the most consistently documented taxon on lichen thalli and is also recorded on bare bark, indicating a facultative, substrate-flexible association. When lichen substrates are grouped ecologically, L. parasitica is reported predominantly from corticolous (epiphytic) lichen systems, whereas terricolous (epigeic) lichens are associated with recurrent records of other myxomycete taxa. Treating lichen thalli as myxomycete microhabitats can improve interpretation of cryptogam-associated forest biodiversity and guide targeted tests of trophic-stage activity within thallus microzones.