Description of Vampyrellids:
Circumscription: Medium to large amoebae with filose/tapering pseudopodia usually finely granular cytoplasm, pseudopodia rarely anastomosing. Mostly ingest the contents of algal and fungal cells, which they gain access to by perforating the cell walls. Feeding amoebae alternating with digestive cysts, cytoplasm frequently orange. Freshwater and marine. Cells uninucleate or multinucleate. Ultrastructural identity: Mitochondria with tubular cristae. Dictyosomes present. No flagella or centrioles known. Cytoplasm with helical arrays (of ribosomes?) Mitotic nuclei with intact nuclear envelopes and intranuclear spindles. Synapomorphy: Tubulocristate filose amoebae with alternation of motile amoebae and digestive cysts.