Morphogenesis and generic concepts in coralline algae — a reappraisal
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In coralline algae, anatomy has long been used for generic definition, in addition to reproductive structures. Coralline anatomy is here analysed according to its two main components: cell behaviour and morphogenesis. The meristems and thir function are explained and the main types of organization are examined in an evolutionary context. Emphasis is given to ontogenetical data such as the occurrence of metamorphosis and progressive development in some species of theLithophyllum complex, which have raised difficulties for generic definitions in the past. Consequently, a certain number of terms (epithallus, hypothallus, perithallus) are clarified and some of them restricted in relation to their morphogenetic significance. As a consequence of this clarification, evolutionary groups are defined and within them parallel phylogenetic lines appear as continuums along which genera are morphogenetic steps.