Vegetative and reproductive morphology of Helminthocladia calvadosii, H. agardhiana and H. reyesii sp. nov. (Liagoraceae, Rhodophyta) from the eastern Atlantic.
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The type species of Helminthocladia, Helminthocladia calvadosii, and two species known from the eastern Atlantic and Mediterranean, H. agardhiana and H. reyesii O'Dwyer & Afonso-Carrillo sp. nov., are described in detail. The species are mainly distinguishable by their habit, the morphology of the cortical fascicles, and the type of carposporangium (undivided single terminal, quadripartite single terminal, and undivided in short chains). The previously controversial reproductive morphology in H. calvadosii has been clarified from observations of plants from northern Spain. In H. calvadosii. simultaneously with gonimoblast development, sterile postfertilization filaments are produced from the suprasupporting cell and some other cortical cells adjacent to the carpogonial branch. The development of these sterile filaments is highly variable within the same area of the plant. S terile filaments can be absent, presenting an entirely naked carpogonial branch below the mature carposporophyte. H. reyesii, known so far only from the Canary Islands, has a unique feature: the elaboration from the suprasupporting cells of sterile moniliform postfertilization filaments that partially or completely surround the carpogonial branch. Additionally, H. reyesii differs from other Helminthocladia species by a unique combination of significant attributes. We analyse the features used at present to delineate the genus Helminthocladia in the Liagoraceae and give a comparative table of the morphological attributes of the species currently accepted in Helminthocladia.