Amoebozoan lobose amoebae (tubulinea, flabellinea, and others)

Abstract

The amoebozoans included here are amoeboid protists that locomote by forward flowing of the internal cytoplasm and protrusion of peripheral, fingerlike or fan-shaped pseudopodia, excluding the myxomycetes and other slime molds, and Archamoebae, which lack classical mitochondria. These lobose Amoebozoa are an eclectic collection of amoeboid organisms. Some are naked without any surface covering, while other species may have a thin organic surface coat (glycocalyx) or delicate scales deposited on the outer cell membrane, with shapes that are species specific. Lobose testate amoebae are enclosed within an organic or mineralized shell (test) with an oral aperture where the tubular pseudopodia emerge. The lobose amoebozoans consume prey (e.g., bacteria, algae, smaller protists, yeast, etc.) by phagocytosis. They are widely distributed globally in aquatic and terrestrial environments. They become dormant cysts under unfavor- able conditions, such as lack of adequate food or drying of the environment, but excyst and become active when environmental conditions improve (or form freeze-resistant, winter resting stages that are not encysted in some soil-dwelling amoebae in temperate regions). The amoebozoan lobose amoebae are significant members of aquatic and terrestrial microbial communities and serve as important linkages in food webs between microbes and higher organisms, such as inverte- brates. Like other Amoebozoa, the lobose amoebae typically have tubular mito- chondrial cristae, which partially distinguish them from the heterolobosean amoebae, with discoidal/flattened cristae. Molecular phylogenetic evidence indi- cates that Amoebozoans are monophyletic, with most, but not all, lobose amoe- bae falling into one of two subclades: Tubulinea (which includes the lobose testate amoebae or Arcellinida) and Discosea.