The Vampyrellid Amoebae (Vampyrellida, Rhizaria)

The Vampyrellida (Endomyxa, Rhizaria) is a group of free-living, predatory amoebae, which is most closely related to the Phytomyxea (plasmodiophorids and phagomyxids). It encompasses about 50 credibly described species that have a characteristic life history with the regular alternation of trophic amoebae and immobile digestive cysts. All known vampyrellid amoebae are naked and filose, but the different species display a broad morphological variety. Vampyrellids also vary greatly in their feeding habits, and range from generalist predators to specialized ‘protoplast feeders’ that exclusively feed on the cell contents of eukaryotic prey. They can be found in freshwater, soil and marine habitats, and appear to be globally distributed. Yet, the phenotypic diversity and ecological roles of the Vampyrellida are still poorly explored. Currently, there are eight well-recognized subclades that comprise four families (Vampyrellidae, Leptophryidae, Placopodidae and Sericomyxidae) as well as some lineages without any phenotypic information. Research on vampyrellids is challenging due to their cryptic occurrence in nature, intricate feeding habits that complicate cultivation, and a convoluted taxonomic history. Here, we review available information about cell structure, diversity, ecology, taxonomy and phylogenetics, and provide an up-to-date introduction to the Vampyrellida that may facilitate future research.