THE FUNGAL COMMUNITY ASSOCIATED WITH THE ROOTS OF SOME RAINFOREST EPIPHYTES OF COSTA RICA

At La Selva Biological Station, Costa Rica, we carried out a survey of the microfungi (Ascomycotina and Fungi Imperfecti (Hyphomycetes and Coelomycetes)) associated with the roots of epiphytic orchids and with selected epiphytes from the Araceae, Bromeliaceae, Piperaceae and Polypodiaceae. Numerous isolations were recovered from surface sterilized roots. The Xylariaceae and Nectriaceae were the major groups of ascomycetes isolated. A large number of Fungi Imperfecti including in the Hyphomycetes, the Ingoldian aquatic Tetracladium, and an unidentified species of Acrogenospora, were recovered. Numerous isolates of Pestalotiopsis and Colletotrichum species comprised the majority of the Coelomycetes identified. Enumerating and analysing the components of the mycobiota in this habitat presents a major challenge as the taxa are mostly microscopic and require painstaking isolation procedures that introduce serious sampling bias to results. Our isolates represent a small part of the spectrum of the mycorrhizal, saprophytic and parasitic fungi that play important roles in sequestering, transforming and translocating nutrients among the primary producers in the epiphytic habitat.