MICROMORPHOLOGICAL ANALYSIS OF TWO CARIBBEAN REEF CORALS

Recent molecular data has shown that the Montastraea “cavernosa” species complex and the Montastraea “annularis” species complex are not sister taxa, indicating that the genus Montastraea is polyphyletic. This disagrees with the traditional classification of Vaughan and others. Recent research has shown that micromorphology, namely the shape and arrangement of septal teeth, may agree with the molecular results. This indicates that molecular data and morphological trees may agree; the correct morphological characters just need to be identified. A first step in identifying these characters and understanding how septal teeth grow, involves the study of variation in micromorphology across a colony. Differences between the upper and lower portions of a coral colony may be caused by astogeny and/or ecophenotypic plasticity. In the current study, the three members of the Montastraea “annularis” complex and the three morphospecies of the Montastraea “cavernosa” complex are examined. Photos are taken of the calical surface of both the top and the bottom of several different colonies using a scanning electron microscope, and compared with microstructure observed in polished and etched sections. Teeth on the columella, mid-septum, upper septal margin, and intercorallite area are examined. Comparisons are made among teeth at different locations within corallites, and between colony tops and bottoms. The results are used to develop 3D models characterizing tooth growth. Based on the models, several characters were identified for use in phylogenetic analyses.