Postfertilization development in Clathromorphum, Melobesia and Mesophyllum with comments on the evolution of the Corallinaceae and the Cryptonemiales (Rhodophyta)

Abstract

The history of classification of the Corallinaceae and the nomenclature of suprageneric taxa in the family are reviewed. The formation of connecting filaments and the presence of an auxiliary complex at the periphery of the female disc are demonstrated in Clathromorphum, Melobesia and Mesophyllum. It is postulated that the progenitor of the Corallinaceae formed conceptacles in which all disc filaments developed receptive carpogonia and post-fertilization development was procarpial. The evolution of the Corallinaceae is hypothesized as involving a gradual reduction of peripheral carpogonial branch systems and a change in the site of initiation of carposporangia from fertilized to unfertilized carpogonial branch systems, resulting in a non-procarpial condition. It is hypothesized that the families of the Cryptonemiales can be grouped into three lines of evolution: the fertile axial line (e.g. Cryptonemiaceae), the scattered polycarpogonial line (e.g. Kallymeniaceae) and the condensed polycarpogonia...