Hydroids (Cnidaria: Hydrozoa) from Tristan da Cunha and St. Helena

Abstract

The present report provides the first account of the shallow water hydroids of St. Helena, which comprises 17 species, and adds nine new records to the hydrozoan fauna of the Tristan da Cunha group of islands, raising their number to 34. A total of 34 species, belonging to five families of Anthoathecata and eight families of Thecata, are discussed herein. Although distributional data are given for each species, brief diagnoses are provided for the lesser known or unidentifiable species, and the common taxa are occasionally accompanied by succinct remarks. Illustrations are provided for nearly all species in order to justify their identification and to facilitate identification by others.Fiordlandia protectaandFilellum bouvetensis,both from Gough Island, represent the second world records and extend their known area of distribution.