Identity ofThaumatoessa(=Thaumaleus)typicaKrøyer, the first described monstrilloid copepod

The holotype of the monstrilloid copepod Thaumatoessa typica Krøyer in Gaimard, 1842–1845(?) (= Thaumaleus typicus Krøyer, 1849), an incomplete, badly damaged, juvenile female nearing its final molt, is redescribed. It fits the current concept of the genus Monstrilla Dana, 1849. The swimming legs and cuticle exhibit three features that are diagnostic of Monstrilla longicomis Thompson, 1890 [Sars, 1921], although M. clavata Sars, 1921, a putative synonym of M. longicomis, is a better match in body size and antennule length. The widely used generic name Thaumaleus Krøyer, the correct original spelling of which is fixed herein, is an objective junior synonym of Thaumatoessa and a subjective junior synonym of Monstrilla. Cymbasoma Thompson, 1888 is removed from the synonymy of Thaumaleus.