Cnidome and Growth of a Medusa of Cirrholovenia tetranema (Leptomedusae, Cirrholoveniidae) in Japan

Abstract

The cnidome, growth of a medusa, as well as the gametes and spawning time, of Cirrholovenia tetranema Kramp (Leptomedusae, Cirrholoveniidae) were studied for the first time. The medusae were collected from six localities: Tsushima Island (Nagasaki Prefecture) as the northernmost geographical distribution in the Pacific; Matsuyama (Ehime Pref.); Shirahama (Wakayama Pref.); Amamioshima Island (Kagoshima Pref.); Tomari in Okinawa Island and Aka in Akajima Island (Okinawa Pref.). These are the first record of this species from each locality and the first record of this species in Japan. The morphological characteristics of the medusae caught in the sea generally agree with those reported earlier from other regions in the world. However, the medusae reared in the laboratory exhibited considerable morphological differences, which are highlighted here.