Abstract.--Based on our examination of type material plus additional specimens, it is concluded that Thysanocardia melanium Popkov is a junior synonym of the northern Pacific T. nigra, Ikeda, with a tentacular crown pigmented in many but not all members of the population, and the shape of its nuchal organ may resemble a bicycle seat, a heart, or a thick-sided V. Apionsoma (Phadeonis) claviformes Popkov is shown to be a junior synonym of A. murinae bilobatae Cutler, this subgenus therefore becomes a nomen nudum. Themiste (Themiste) maculosum Popkov is a valid new species from the Sea of Japan.
Publ. Seto Mar. Biol. Lab., 38:34-43, 1997