A new species of large and highly contractile hydroid in the genus Candelabrum (Hydrozoa: Anthoathecatae) from southern Oregon, U.S.A.

Abstract

A new species of hydroid, Candelabrum fritchmanii, is described from Cape Arago, Oregon, U.S.A. Specimens were collected from the intertidal region underneath boulders. This new species' standing with respect to other members of the genus is discussed. The claspers in the blastostylar region of the new species show similarities to the North Atlantic Candelabrum cocksii. However, three specimens had multiple, connected polyps at varying stages of development and the cnidome differs between C. cocksii and the new species, leading to the erection of a new species. The polyp cnidome consists of desmonemes, heteronemes (microbasic mastigophores and homotrichous microbasic euryteles), and stenoteles and the actinula cnidome consists of desmonemes, haplonemes (atrichous isorhizas), and stenoteles. Emendations to the family, subfamily, and genus diagnoses are presented to accommodate these findings. Observations are also presented on actinula development and the ensnaring, predatory feeding behavior of the highly contractile polyp.