MICROMORPHOLOGICAL CHARACTERS PROVIDE FURTHER EVIDENCE OF SPLIT WITHIN EUPHYLLIDAE (ORDER: SCLERACTINIA)

Coral reefs form the most diverse marine ecosystem, but are increasingly threatened by pollution, disease, bleaching, and ocean acidification. Taxonomy is vital to directing conservation efforts. Taxonomic revision within Scleractinia has been hampered by difficulty finding informative nuclear markers and a slow mitochondrial rate of change in addition to traditional morphological characters and molecular data creating consistently conflicting phylogenies within scleractinian corals. Traditional morphological characters are often convergent between groups we now understand to be distantly related. This homoplasy has understandably negative repercussions within morphology based phylogenetic analyses. Micromorphological characters are best viewed under scanning electron microscopy, are linked to how the animal secretes its skeleton, and consist of differences in septal shape, granulation, and development of thickening deposits. Micromorphological characters also show character patterns that are more consistent with molecular phylogenies than traditional characters provide. Here I examine the split within the Pacific polyphyletic family Euphyllidae (class: Anthozoa, order: Scleractinia). Molecular phylogenies conclude that Euphyllidae consists of two distantly related groups. Morphological characters are necessary to discuss evolutionary patterns through geologic time and understanding the relationships between fossils and extant taxa. I have found micromorphological characters that provide distinction between the two family-level clades formerly assigned to Euphyllidae. Neither group contains members that had been exclusively assigned to Euphyllidae. Euphyllia is grouped with Ctenella (previously assigned to Meandrinidae) and Galaxea (previously within Oculinidae) on the basis of smooth septal margins, patterns of granulation and smoother thickening deposits. Physogyra and Plerogyra were linked to Blastomussa (Mussidae) and some members of Plesiastrea (Faviidae) by the robustness of their thickening deposits and different patterns of granulation.