Molecular identification and classification of Cochlonema euryblastum, a zoopagalean parasite of Thecamoeba quadrilineata

Free-living amoebae can serve a great variety of organisms, predominantly bacteria but to a certain extent also fungi, as a suitable host supplying them with nutrients and protecting them from adverse environmental conditions. In the current study 18S rDNA sequencing was performed to identify a fungal parasite in a Thecamoeba quadrilineata isolate. This parasite morphologically resembled Cochlonema euryblastum, a member of the order Zoopagales, which comprises parasitic species on fungi and invertebrates. Sequence analysis corroborated the morphological identification and the fungal parasite clearly can be assigned to the Zoopagales. Phylogenetic analysis revealed C. euryblastum clustering with two representatives of the mycoparasitic family Piptocephalidaceae. This zooparasitic-mycoparasitic clade represents a sister group of a clade including another member of the Piptocephalidaceae and two other zooparasitic families. Thus, the addition of C. euryblastum to the zoopagalean tree further confirms the finding that molecular data do not support the traditional classification of the Zoopageles.