[1][2] Since the 7th edition of Bergey's manual (=top authority in bacterial nomenclature), other authors have given the etymology to be: Greek pseudēs (ψευδής, false) and monas (μονάς, single unit or monad), which can mean "false unit".
One speculation is that the name was chosen simply out of aesthetics,[4] while the most plausible theory states that Migula intended it as false Monas,[4] a nanoflagellate protist (Chrysophyceae: Ochromonadales: Ochromonadaceae: Chrysomonadida: Ochromonadidae).
Subsequently, the term "monas" was used in the early history of microbiology to denote single-celled organisms.
[4] In English to make a vernacular name for members of a genus, i.e. trivialising the scientific name, the scientific name is taken and written with sentence case and in roman type (i.e. "standard") as opposed to uppercase italic, the plurals are generally constructed by adding an "s", regardless of Greco-Roman grammar.
The use of the stem for non-nominative cases is seen more often in botany, where trivialisation is more common, e.g. a bromeliad is a member of the genus Bromelia.