Abstract
Four species of Thenea are recognized in the North Atlantic instead of two, T. muricata (Bowerbank, 1858) and T. abyssorum Koltun, 1959, as currently believed. T. valdiviae Lendenfeld, 1906 and T. levis Lendenfeld, 1906, are removed from the synonymy with T. muricata, and the first description of fully grown specimens of T. levis is given. Most arctic records of T. muricata refer to T. valdiviae. Giant multi-oscular specimens of T. muricata and T. valdiviae are considered to originate from fusion of several smaller specimens.
