(fig. 4 L)
Medusa hemisphaerica Linnaeus, 1767: 1098.
Clytia hemisphaerica.— Cornelius, 1982: 73 –82, fig. 9.— Cornelius 1995 b: 252, fig. 57.— Medel & López-González, 1996: 205.— Medel & Vervoort, 2000: 34 –38.—Peña Cantero & García Carrascosa, 2002: 147–148, fig. 28 c–d.— Bouillon et al. 2004: 194, figs. 108 H–K.— Vervoort, 2006: 271.— Wirtz, 2007: 14.
Campanularia johnstoni.— Da Cunha, 1940: 109, 118.— Da Cunha, 1944: 9, 59, fig. 34;
Material studied. Ormonde, stn 1: abundant, fertile colonies, on Zonaria tournefortii, DBUA 1507.10. Ormonde, stn 2: few specimens, fertile colonies, on Zonaria tournefortii and Aglaophenia pluma, DBUA 1507.01. Ormonde, stn 3: abundant, fertile colonies, on Zonaria tournefortii, DBUA 1507.02. Ormonde, stn 4: abundant, fertile specimens, on Zonaria tournefortii (in higher abundance), Eudendrium armatum, Sertularella ellisii and other species of algae; usually in different algae of those overgrown by Orthopyxis integra; DBUA 1507.03. Gettysburg, stn 5: abundant, fertile colonies, on Zonaria tournefortii and Aglaophenia pluma. Gettysburg, stn 6: abundant, fertile, on Zonaria tournefortii, DBUA 1507.05. Gettysburg, stn 7: very abundant, fertile colonies, on Zonaria tournefortii, DBUA 1507.06. Gettysburg, stn 8: some specimens, fertile colonies, on Zonaria tournefortii, DBUA 1507.07. Gettysburg, stn 9: abundant, fertile colonies, on Zonaria tournefortii and calcified Bryozoa, DBUA 1507.08. Gettysburg, stn 10: abundant, overgrowing Aglaophenia kirchenpaueri, Sertularella gayi and Zonaria tournefortii, DBUA 1507.09.
Remarks. Clytia hemisphaerica was the most abundant and frequent hydroid species collected. Pedicels of hydrothecae in some colonies are extremely annulated. This is the first record of this species in the Gorringe.
Reported distribution. Eastern Atlantic.—Very common (e.g. Russell 1953; Cornelius 1982; Medel & Vervoort 2000), from Iceland (Broch 1918) to South Africa (Millard 1975). Herein reported for the first time in the Gorringe.
Mediterranean.—Well dispersed (e.g. Medel & Vervoort 2000; Peña Cantero & García Carrascosa 2002)
Elsewhere.—Nearly cosmopolitan through shallow waters, possibly absent from the Antarctic and Arctic, but many old records of the species are dubious (e.g. Ralph 1957; Kramp 1961; Calder 1991; Cornelius 1995 b). The type locality of the species is in Belgium.