Thecostraca is a class of typical crustaceans. There are 2077 species of Thecostraca, in 358 genera and 67 families. It includes groups like Barnacles.
Definition: number of currently described and taxonomically accepted marine species in this clade (Appeltans et al. 2012. The Magnitude of Global Marine Species Diversity. Current Biology 22, 2189–2202. http://dx.doi.org/10.1016/j.cub.2012.09.036)
