Ramicristates

Circumscription: Amoeboid organisms with tubular cristae that branch. Amoebae are distinguished by moving and/or acquiring food by means of pseudopodia, which can be filose, lobose, branching, conical, or with subpseudopodia. This group contains the bulk of the naked lobose amoebae of previous classifications, the lobose and filose testate amoebae. Three groups-stercomyxids, dictyostelids (a type of cellular slime mould), and acanthamoebids have a lamellate microtubule organizing centre. Dictyostelids and acanthamoebids use cellulose, the former in the stalks, which support spores and in the cysts of the latter. The true slime moulds (the eumycetozoa = protostelids and myxomycetes) are included. In these, the individual cells aggregate into a syncitial plasmodium that moves with an ebb and flow pattern. The syncitium produces a fruiting body from which are released resistant distributive cysts (spores). The eumycetozoa have a biflagellated stage in life cycle-one of the few types of ramicristates with flagellated forms. Leucodictyon is another plasmodial organism with flagellated distributive stage. Ultrastructural identity: Mitochondria with irregular tubular and branching cristae. Mitosis variable but typically with nuclear envelope either breaking down at poles or breaking down entirely. Spindle microtubules arising from amorphous material near the nucleus or from basal bodies if flagella are present. Synapomorphy: Mitochondriate eukaryotes with branched tubular mitochondrial cristae. Composition: The euamoebae (corresponding broadly with the naked lobose Amoebae); centramoebae (i.e., with lamellate microtubule organizing centre: Acanthamoebae Stereomiyxidae and Dictyosteliidae), the leptomyxids, Trichosphaerium, lobose testate amoebae (Testacealobosea), filose testate amoebae (Testaceafilosea), and Gromia, protostelids, and myxomycetes. This group contains the bulk of the naked lobose amoebae of previous classifications, the lobose and filose testate amoebae.