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Taxonomic Notes on Polyp and Medusa of Sarsia nipponica Uchida (Hydrozoa : Corynidae) from the Type Locality in Japan

1991; Seto Marine Biological Laboratory; Volume: 35; Issue: 1-3 Linguagem: Inglês

10.5134/176173

2189-2695

Shin Kubota,

Coastal wetland ecosystem dynamics

Life cycle of Sarsia nipponica Uchida, 1927 was revealed through laboratory-culturing of specimens from the type locality, Shirahama, Wakayama Prefecture, .Japan.The morphology of its polyp, newly liberated medusa, and mature medusa was redescribed, stressing new character states observed in these developmental stages.The nematocyst complement and egg size of this species were described for the first time.The taxonomic evaluation of filiform tentacles, which were newly found in the present well-developed polyp, was particularly made.Sarsia nipponica was originally described by Uchida (1927), based on several mature medusae found in plankton samples from Shirahama, Wakayama Prefecture, Japan, particularly a mature specimen collected there on November I, 1922 by the late Mr. Jiro Ikari (Yamada, 1983;Komai and Ikari, 1929).For this species, field-collected polyps and/or newly liberated medusae from them in the laboratory have been described by Uchida (1940), Nakamura (1940, 1941), and Hirohito, H. M. the Emperor Showa ( 1988) based on the specimens from Misaki and Hayama, Kanagawa Prefecture, without confirming their mature medusae.From the type locality no polyps have been collected, while Yamazi (1958) recorded the medusa as a rare species among the hydromedusae found in Tanabe Bay and its environs.From only one locality other than the type locality, the mature medusa was recorded and described by Chow and Huang (1958) based on 10 specimens from Chefoo, China.During a faunal survey of hydrozoans at Shirahama, Wakayama Prefecture, a tiny colony of hydroid polyps was collected from an intertidal red alga Hypnea sp. on September 6, 1989, which were identified to Sarsia nipponica.The polyp bore a small number of medusa buds and all of them released as the youngest medusae within 12 hours after collection.These medusae were reared in the laboratory for two weeks to reveal the life cycle.Each individual was kept in a 60 cc polystyrene vessel filled with filtered seawater from Oshoro, Hokkaido at 22°C and was fed with Artemia nauplii.By this culture, mature medusae were obtained, but maintaining polyps transplanting zooids onto polystyrene or glass vessels were unsuccessful.Comparing the present specimens with the description given so far, some new character states were observed in every developmental stage.Nematocyst complement of polyp and medusa and egg size were examined and revealed for the first time.In this paper, the morphology of the polyp, the newly liberated medusa, and the mature medusa of S. nipponica is redescribed, together with these new taxo-Pub!.