Eremithallus costaricensis (Ascomycota: Lichinomycetes: Eremothallales), a new fungal lineage with a novel lichen symbiotic lifestyle discovered in an urban relict forest in Costa Rica.

摘要

The NSF-funded TICOLICHEN biodiversity inventory in Costa Rica revealed a new fungal lineage with a novel type of lichen symbiosis, here described as Eremothallales ordo novus and Eremothallaceae familia nova, with the single species Eremithallus costaricensis genus et species nova, the 'Costa Rican hermit crab lichen'. Instead of forming a proper thallus enclosing the photobiont, the Trentepohlia algal cells are located in groups within individual periderm cells of the tree bark, from where they connect to the superficial apothecia of the lichen fungus by hyaline fungal hyphae. Such a mode of lichenization is unknown in other lichenized fungi and raises the question about the mechanics of algal cell positioning during the development of the lichen. Although showing morphological and anatomical similarities with Ostropales, molecular analysis using a three gene approach (mtSSU, nuLSU, RPB1) places the new lichen fungus outside the Lecanoromycetes. Instead, the taxon forms a separate lineage presumably close to Lichinales in the Lichinomycetes. The novel lichen fungus was found in a small forest remnant on the campus of the University of Costa Rica (Leonelo Oviedo Ecological Reserve), founded by the renown Costa Rican ecologist and conservationist Dr Luis Fournier, inmidst the extensive deforested area of the Costa Rican central valley. This underlines the importance of such refugia for conserving biodiversity and, as in this case, even previously unknown evolutionary lineages.