Redescription of Antipathes dichotoma Pallas, 1766 (Cnidaria: Anthozoa: Antipatharia)

The species Antipathes dichotoma was established by Pallas in 1766 on the basis of a description given by Marsigli (1725) of a specimen collected in the Mediterranean off the coast of Marseille. Marsigli's specimen (Lithophyte no. 9) was described and illustrated as a loosely dichotomously branched colony with strong spines and a biserial arrangement of polyps, with each polyp appearing to have only two tentacles. Pallas (1766) had no additional specimens on which to expand and clarify the species definition. Brook (1889) was the first worker who provided a more detailed description of the species based on a specimen from the Bay of Naples. Brook's specimen did not closely match Marsigli's illustration in that the branching was more irregular and not so dichotomous. Later workers have followed Brook's diagnosis and, in general, most of the specimens described from the Mediterranean more closely resemble Brook's specimen than Marsigli's illustration. Brook (1889) designated Antipathes dichotoma Pallas as the type species of the genus Antipathes. Of the five species originally placed in the genus by Pallas, A. dichotoma was the only species of two retained in the genus (the other was A. foeniculacea Pallas) for which Brook had a specimen. Brook, however, did not specifically designate his specimen as a neotype. It is unlikely that Marsigli's specimen is still extant, and because of confusion over the identity of this species with others from many different localities, it seemed necessary to describe the species on the basis of modern techniques and to provide sufficient information to help differentiate this species from a number of others which had previously been synonymized with it.