Monotypic Maxillopoda genera

Stygotantulus is a genus of crustacean with the sole species Stygotantulus stocki. It lives as an ectoparasite on harpacticoid copepods of the families Tisbidae and Canuellidae. It may be the smallest arthropod in the world, at a length of less than . The specific name stocki commemorates Jan Hendrik Stock, a Dutch carcinologist.

Cephalobaena is a genus of crustaceans in the subclass Pentastomida. It has only one species, Cephalobaena tetrapoda, found in South America parasitizing snakes such as Lygophis lineatus and Crotalus durissus.