Abstract
Morphological classification of zooxanthellate (hermatypic) corals (hereafter corals) in the Screlactinia is currently based on skeletal features of the corallite and colony forms. These corals, however, have few taxonomically significant morphological characteristics because such characters show polymorphism, intraspecific variation, and phenotypic plasticity in response to environmental factors. Quantitative description of taxonomic features that comprise differences between morphologically similar genera and/or species is challenging. Recently in Japan, picture books and identification guides of the corals that focus mainly on their living features have become popular. These publications promote awareness of the corals, but they have decreased attention to the skeletal features of corals. A number of these publications do not adhere to the International Code of Zoological Nomenclature, especially with regard to scientific names, thereby reducing the current stability of coral taxonomy. This complicates the effort to obtain a consensus on the taxonomic identification of coral species, which is important for comparing results of studies, past and present. Application of molecular phylogenetic analyses to corals has provided useful information for understanding the relationships among closely related families and/or genera as well as neighboring species in the same genus. These analyses should be used to revise the traditional taxonomic scheme, which is based only on morphological characteristics. Compounding the difficulty, past studies may also have used misidentified coral species. To establish greater taxonomic consistency among coral species, the morphological characteristics used for traditional taxonomy should be quantitatively compared among closely related species. Identification of new morphological characteristics of the external or internal skeletal structures of colony and/or corallite that are consistent with available phylogenetic evidence is also necessary. Because of the possibility of misidentification, efforts should be taken to retain samples of soft tissues of these species as well as skeletal specimens of their corallite and/or colonies.
