The Ability ofTetrahymena utriculariae(Ciliophora, Oligohymenophorea) to Colonize Traps of Different Species of Aquatic CarnivorousUtricularia

The host specificity of the recently described ciliate speciesTetrahymena utriculariaewas tested in a greenhouse growth experiment, which included 14 different species of aquaticUtriculariaas potential host plants. We confirmed the high specificity of the interaction betweenU. reflexaandT. utriculariae, the former being the only tested host species able to maintain colonization for prolonged time periods. We conclude that this plant-microbe relationship is a unique and specialized form of digestive mutualism and the plant-microbe unit a suitable experimental system for future ecophysiological studies.