The holotype of the monstrilloid copepod Thaumatoessa typica KROYER in
GAIMARD, 1842-1845(?) (= Thaumaleus typicus KROYER, 1849), an incompl
ete, badly damaged, juvenile female nearing its final molt, is redescr
ibed. It fits the current concept of the genus Monstrilla DANA, 1849.
The swimming legs and cuticle exhibit three features that are diagnost
ic of Monstrilla longicornis THOMPSON, 1890 [SARS, 1921], although M.
clavata SARS, 1921, a putative synonym of M. longicornis, is a better
match in body size and antennule length. The widely used generic name
Thaumaleus KROYER, the correct original spelling of which is fixed her
ein, is an objective junior synonym of Thaumatoessa and a subjective j
unior synonym of Monstrilla. Cymbasoma THOMPSON, 1888 is removed from
the synonymy of Thaumaleus.