Benthic shallow-water hydroids (Cnidaria, Hydrozoa) of the coast of São Sebastião, Brazil, including a checklist of Brazilian hydroids

The paper presents the results of a general survey of the hydroid fauna of the coastal region of the São Sebastião Channel, São Paulo State, Brazil. Intensive collecting in the intertidal and infralittoral zones, from 1984 to 1992, led to the discovery of many species, some of which are small and inconspicuous. Out of 59 species of hydroids (17 athecate and 42 thecate) described and illustrated, three are new records for the Atlantic Ocean, six for the western South Atlantic, and 21 for the Brazilian coast. The medusa stage of Asyncoryne ryniensis and the cnidome of 24 species are described for the first time. The paper also contains a synopsis of the hydroids recorded from the Brazilian coast, the list now including 107 species. Pseudostenotele nematocysts, recently described, were found in three species of Haleciidae (Halecium dichotomum, H. tenellum, Ophiodissa spec), in four species of Halopterididae (Halopteris constricta, H. diaphana, H. buskii, Monostaechas quadridens) and in four Plumulariidae (Monotheca margaretta, Plumularia floridana, P. strictocarpa, Ventromma halecioides).