Microstructural differences observable within septa are currently recognized as major phylogenetic criteria among Scleractinia. If the emergence of molecular techniques provides a good mean of assessing these criteria, some recent results using molecular approach seem to give only low support for microstructural-based phylogenetic relationships of Scleractinia. This, however, may result from the numerous uncertainties concerning the microstructural pattern of species upon which major taxa are based. Three-dimensional characters of septal growth units and their variability have here been investigated using the specimens of Favia fragum included within the Milne Edwards Collection, these being the oldest reference material still available today. Integrating these data with results from the most recent work on this species leads to the reconstruction of the three-dimensional pattern of septal architecture. The phylogenetic significance of this requires assessment with alternative approaches.
Favia fragum, Scleractinia, skeletogenesis.