Stygotantulus
Stygotantulus is a genus of crustacean with the sole species Stygotantulus stocki, that lives as an ectoparasite on harpacticoid copepods of the families Tisbidae and Canuellidae. It is one of the smallest arthropods in the world, at a length of less than. The specific name stocki commemorates Jan Hendrik Stock, a Dutch carcinologist.
Another contender for the world's smallest arthropod is Tantulacus dieteri, with a total body length of only.