Acaulopage, free-living amoebae, slime molds
Amoebophagous fungi, Zoopagales,
Samples from mud and decaying plant material from a pond in Southern Sweden were transferred onto NN-agar plates. Within 4-5 days, a meshwork of fungal hyphae with adhering trophozoites of naked free-living amoebae developed on the plates. Conidia formation was induced by the addition of sea salt to the agar. Based on the morphology of its characteristic conidia this amoebophagous fungus was identified as Acaulopage tetraceros DRECHSLER 1935. Clonal cultures of A. tetraceros were established for experimental evaluation of its prey pattern and for molecular characterisation. This strain of A. tetraceros accepted as prey not only various free-living amoebae but also the amoebal stages of slime moulds, including Dictyostelium and Physarum species, when co-cultivated in vitro. The formation of conidia was induced by all strains tested, except two Saccamoeba strains, two Sappinia strains and one strain of Naegleria clarki, that were however still suited as prey. Sequencing of the 18S rRNA gene of the fungus resulted in a sequence of 1762 bp in length with highest identity to Cochlonema sp. and other zoopagalean fungi. To the best of our knowledge, these are the first sequence data of an amoebophagous fungus.