Anthopleura sola, a new species, solitary sibling species to the aggregating sea anemone, A-elegantissima (Cnidaria: Anthozoa: Actiniaria: Actiniidae)

The Sunburst Anemone, a common inhabitant of rocky shores in central and southern California, is here designated as Anthopleura sola, new species. This large, conspicuous, solitary sea anemone was previously considered a non-clonal variant of the well-known, clonal Aggregating Anemone, A. elegantissima. Although polyps of these two species are similar in appearance and in cnidae, documented differences in population genetics, ecology, biogeography, development, and life history are evidence of a recently evolved sibling-species pair. Where the two species co-occur, they are readily distinguished in the field by differences resulting from their different life histories. In A. elegantissima, longitudinal fission results in aggregations of small polyps. Anthopleura sola does not divide and instead grows into larger, isolated individuals that have more often been confused with specimens of the Giant Green Anemone, A. xanthogrammica.