Abstract
The prokaryotic, generic names Micromonas Murdoch and Shah 2000 and Quadricoccus Maszenan et al. 2002 are illegitimate* because they are later homonyms of the names Micromonas Manton and Parke 1960 (alga) and Quadricoccus Fott 1948 (alga). [Principle 2, Rule 51b(4) of the Bacteriological Code (1990 Revision)]. Such names have no claim to be correct names (Principle 6) and, therefore, replacement generic names must be proposed (Rule 54).