THE LIFE HISTORY OF EPERETMUS TYPUS BIGELOW AND THE SYSTEMATICS OF THE FAMILY OLINDIADIDAE (LIMNOMEDUSAE)

Abstract

The olindiadiid medusa, Eperetmus typus was first described by BIGELOW (1915) as a new species of a new genus from Alaska based on a single medusa. Since then this species has sometimes been reported from the northern Pacific; two specimens from Alaska (BIGELOW, 1920), several specimens from Vancouver (FORSTER, 1923), three and many specimens from Hokkaido, northern Japan (UCHIDA, 1929, 1940), one specimen from Friday Harbor (MACKIE and MACKIE, 1963). All of them are the records of the medusan stage. Recently, the author found the hydroid colonies of this species from Akkeshi Bay, Hokkaido, and successfully reared the medusae liberated from these hydroids till matured (NAGAO, 1969a). On the one hand, from May to November in 1966 and 1967, many medusae of Eperetmus typus in various developmental stages were obtained by surface tows in the bay. The young medusae obtained by the surface tows coincided with the young medusae reared in the laboratory. The present paper deals mostly with the development of the medusan stage and the systematic considerations of the family Olindiadidae.