Redescrição e ciclo de vida de Clytia gracilis e Clytia linearis (Cnidaria, Hydrozoa, Campanulariidae). / Redescription and life cycle of Clytia gracilis and Clytia linearis (Cnidaria, Hydrozoa, Campanulariidae).

AUTOR(ES)
DATA DE PUBLICAÇÃO

2000

RESUMO

he life-cycles of Clytia linearis (Thornely, 1899) and two species with characters considered diagnostic of Clytia gracilis (M. Sars, 1850) – Clytia cf. gracilis sp. 1 and Clytia cf. gracilis sp. 2 – have been studied based on specimens collected in the shallow subtidal coast of São Sebastião and Ilhabela, southeast Brazil, between February 1999 and April 2000. Medusae were cultured in the laboratory (22-24oC). Colonies of C. linearis are monosiphonic, sympodial, up to 21.5mm high and bearing up to 26 hydranths and 10 gonangia. Adult medusae reached 2.5-3.6mm in diameter, and up to 29 tentacles and 28 statocysts. The presence of microbasic mastigophore type C nematocysts distinguishes adult medusae of C. linearis from other species of Clytia. A band of microbasic mastigophore type A nematocysts in the umbrella, at the level of the circular canal, distinguishes adult medusae of Clytia cf. gracilis spp. 1 and 2 from other species of the genus. Adult medusae of C. cf. gracilis sp. 1 and C. cf. gracilis sp. 2 have up to 16 tentacles, and can be distinguished by the diameter of the umbrella: 6.6-10.1mm and 3.6-5.5mm, respectively. Colonies of C. cf. gracilis sp. 1 are usually erect and dichotomous, the hydrothecae are elongated and the gonothecae present in the hydrorhiza and pedicels. These features closely match with the description of C. gracilis, but both species differ in the morphometry of the gonothecae and microbasic mastigophore type B nematocysts: about 15mm (length) for C. gracilis and 9-10mm for C. cf. gracilis sp. 1. Type B nematocysts of C. cf. gracilis sp. 2 (about 14.5mm in length) are more similar in size to those of C. gracilis. However, the former species differs from the latter in the shape of the hydrothecae, by having gonothecae only at the hydrorhiza and polysiphonic well-developed colonies. A third species, C. cf. gracilis sp. 3, is described based on an unfertile colony. Aspects of the systematics of Clytia are discussed.

ASSUNTO(S)

brazil taxonomy ilhabela são sebastião brasil hydroids systematics hydrozoa life-cycle medusas clytia gracilis sistemática campanulariidae taxonomia ciclo de vida nematocistos nematocysts hidróides cnidaria medusae clytia linearis

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