Stichodactyla haddoni (Saville-Kent, 1893)

Titus, Benjamin M., Bennett-Smith, Morgan F., Chiodo, Tommaso & Rodríguez, Estefanía, 2024, The clownfish-hosting sea anemones (Anthozoa: Actiniaria): updated nomenclature, biogeography, and practical field guide., Zootaxa 5506 (1), pp. 1-34 : 5

Notes on Stichodactyla haddoni & Stichodactyla gigantea

Among the most complicated nomenclatural problems to arise among the clownfish-hosting sea anemones is the one that involves the species that have long been recognized by Dunn (1981) and the broader community as S. haddoni ( Saville-Kent, 1893) and S. gigantea ( Forsskål, 1775) . Recently, Bennett-Smith et al. (2021) demonstrated that what Dunn (1981) recognized as S. gigantea does not occur in the Red Sea, nor in the broader Indian Ocean West of the Bay of Bengal. Their conclusion was that the species currently recognized as S. gigantea has never occurred in the Red Sea, and thus, Dunn (1981) had misattributed Forsskål’s 1775 description of Priapus giganteus to the wrong clownfish-hosting sea anemone species. Bennett-Smith et al. (2021) document two clownfish-hosting species from the Red Sea in the genus Stichodactyla : S. haddoni and S. mertensii . Unfortunately, as Dunn (1981) and Bennett-Smith et al. (2021) both noted, Forsskål’s description is not diagnostic and the type specimen has not been found. Dunn (1981) ultimately elevated Forsskål as the authority of the species she recognizes as S. gigantea based on Forsskål’s comment on the extreme adhesiveness of the tentacles. Both S. haddoni and S. mertensii have adhesive tentacles where they co-occur in the Red Sea and combined with the lack of diagnostic description from Forsskål, the name S. gigantea could equally be applied to either species.

Further complicating matters is Dunn’s nomenclature for these three taxa in the genus Stichodactyla have been consistently applied in the scientific community for over 30 years, and S. haddoni is an especially popular animal in the ornamental aquarium trade. Swapping and synonymizing species names for two animals that have long been recognized as clownfish-hosting sea anemones does not foster nomenclatural stability and will likely serve to further the long-standing confusion surrounding the taxonomy and identification of these anemones in the literature and among aquarium trade hobbyists. As such, we have petitioned the ICZN to retain Dunn’s (1981) usage for S. haddoni ( Saville-Kent, 1893) and S. gigantea ( Forsskål, 1775) (Rodríguez et al. in press: case 3885). This will maintain nomenclatural stability at the species level while minimizing the number of species-level name changes among these close relatives until a thorough revision of morphological and genomic data is completed.