Mastigamoeba

Mastigamoeba is a genus of the Archamoebae group of protists. Mastigamoeba are characterized as anaerobic, amitochondriate organisms that are polymorphic. Their dominant life cycle stage is as an amoeboid flagellate. Species are typically free living, though endobiotic species have been described. The genus is relatively understudied, and under contention regarding the composition of the genus. There are currently 9 described species of Mastigamoeba. They share many similarities with other Archamoebae, such as Mastigella and Entamoeba. Mastigamoeba is often referred to as Phreatamobea. These two are synonymous, and their classification often causes debate amongst researchers. It includes Mastigamoeba balamuthi. Mastigamoeba invertens is now classified as Breviata anathema. Mastigamoeba was described as a genus of species characterized by an ameboid body with a hyaline based cytoplasm and a flagellum. Due to its similarities to genera such as Mastigella and Mastigina, the genus Mastigamoeba was specified in 1891 to only include organisms with the following features: amoeboid flagellates with hyaline based cytoplasm, a direct connection between the flagellum and the nucleus, lateral pseudopods, and nucleus with an elongated shape. Throughout the 20th century, hundreds of species were described under the genus Mastigamoeba based on external morphological characteristics alone. However, recent discoveries regarding life cycles have shown that a single organism takes on many morphologies throughout its life cycle, putting the number of described species into question. There are currently 9 confirmed distinguished species of Mastigamoeba, with many more in contention. Tom Cavalier-Smith described the class Archamoebae in 1983 and among others included the order Mastigamoebid, which includes the genus Mastigamoeba.  Historically, amoeboid flagellates have been considered Pelobionts, which encompasses mastigamoebids and pelomyxids. There is contention with the naming of the genus. Mastigamoeba and the genus Phreatamoeba are now considered synonymous by some researchers, though this being challenged by others.