Structure and reproduction of Spongites wildpretii sp. nov. (Corallinaceae, Rhodophyta) from the Canary Islands, with observations and comments on S. absimile comb. nov.

Abstract

On the basis of a critical study of the holotype specimen, Lithophyllum absimile Foslie & Howe is transferred to the genus Spongites Kützing, and plants previously reported from the Canary Islands as Lithophyllum absimile or Neogoniolithon absimile (Foslie & Howe) Cabioch are described as a new species: Spongites wildpretii Afonso-Carrillo. The new species is described anatomically and compared with the holotype specimen of Lithophyllum absimile and plants from Japan assigned to L. absimile. Spongites wildpretii is distinguished from the holotype of L. absimile by the lack of excrescences, by the less-developed perithallium and by the small size of cells. It is distinguished from the Japanese plants mainly by reproductive attributes (conceptacle dimensions, conceptacle roof structure and occurrence of columella). A detailed reproductive account of S. wildpretii is provided with special reference to carposporophyte ontogeny. The diagnostic value of the post-fertilization characters as accessory attributes for segregating Spongites from related genera is discussed. Collapse of the conceptacle roof and the regeneration of perithallial tissue of the tetrasporangial and carposporangial conceptacle chambers also are described.