Studies on the Mastophora–Lithoporella complex (Corallinaceae, Rhodophyta)

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Abstract
A comparative study of reproduction in the type species of Mastophora and Lithoporella (Corallinaceae, Rhodophyta) has revealed that differences associated with tetrasporangial conceptacle development and structure provide a reliable basis upon which to delineate the two genera. In Lithoporella melobesioides, tetrasporangial conceptacles are characterized in part by the presence of a layer of elongate perithallial cells, roof formation from filaments interspersed among tetrasporangia and the absence of a columella. In Mastophora rosea, tetrasporangial conceptacles lack a layer of elongate perithallial cells, have roofs formed from peripheral filaments surrounding fertile tissue and possess a columella. The two patterns of tetrasporangial conceptacle development differ, both from one another and from the patterns recorded for other' Corallinaceae. Details of gametangial conceptacle structure and ontogeny are provided for the first time, and a number of stages of carposporophyte ontogeny are presented including transfer of diploid nuclei from carpogonium to auxiliary cell. The taxonomic implications of all results are considered, generic concepts and typification are reviewed and emended diagnoses of the two genera are presented. The relationships of Mastophora and Lithoporella to other genera of non-geniculate Corallinaceae also are discussed briefly.