Studies on Dasyaceae. 1. Reproductive structures of Eupogodon planus and E. spinellus (Ceramiales, Rhodophyta) from Corsica (Mediterranean)

Abstract

Reproductive structures of Eupogodon planus (C. Agardh) Kützing and E. spinellus (C. Agardh) Kützing, including the tetrasporangial stichidia of both species and mature carposporophytes and spermatangial branches of E. spinellus, are described for the first time. Early procarp development of E. spinellus is also described. The female reproductive system of E. spinellus closely resembles that in the genus Dasya C. Agardh, the proposed sister genus of Eupogodon Kützing. Similar features include procarp position on the central axis, number of periaxial cells and manner of their formation, location of the supporting cell, number and arrangement of sterile cells, absence of pericarp initials before fertilization, the monopodial branching of the gonimoblast, and the development of the carposporangia in terminal chains. As regards the tetrasporangial stichidia, however, the two genera differ markedly in the number of sporangia per stichidial segment, although sharing the character of postsporangial cover cells that only partially envelop the tetraspores. The taxonomic status of both Eupogodon species is discussed in light of the present findings, and the family Dasyaceae is re-evaluated on the basis of reproductive structures.