Antipathidae Ehrenberg 1834

Family Antipathidae Ehrenberg, 1834

This family was the first to be established and contains the highest number of species, with around 130 descriptions (Opresko 1972, 1974; Molodtsova & Opresko 2020). The family is characterized by unbranched species that have a single stem, and branched forms that can be bushy, arborescent, fan-shaped or bramble-like. Clearly defined pinnules are never present, but flabellate species can appear pinnulate because of the bilateral arrangement of the smallest terminal branches. The spines are smooth or papillose and can be simple, forked or multi-lobed. The polyps have ten mesenteries and range from 1 to 3 mm in size (Brugler et al. 2013). Polyps are not elongate in the transverse plane and sagittal tentacles are generally longer than the lateral tentacles (Opresko 2005 b; Wagner 2015a).

There are currently nine genera within the Antipathidae: Antipathes, Arachnopathes, Hillopathes, Pteropathes, Stichopathes, Cirrhipathes, Pseudocirrhipathes, Allopathes and Blastopathes. Members of this family typically occur at depths less than 200 m, but some species may occur deeper (Opresko 2019). Revisions have been published to clarify the taxonomic position of many antipatharian families (Opresko 2001, 2002, 2003b, 2004, 2005a, 2006), but the family Antipathidae still needs a major revision since colony and skeleton morphologies are very heterogeneous, and genomic studies have identified a number of polyphyletic groups (Bo et al. 2012 a; Brugler et al. 2013). For example, the type species of the genus Antipathes, Antipathes dichotoma Pallas, 1766, is more closely related to members of the family Aphanipathidae than to many members of Antipathidae. Future studies gathering molecular and morphological data from large sets of widely distributed specimens will be needed to reassess the current classification of both families (Brugler et al. 2013).