Morfologia vegetativa i reproductora de Neurocaulon foliosum (Furcellariaceae, Gigartinales, Rhodophyta)

Abstract

Neurocaulon foliosum (Meneghini) Zanardini ex Kützing is a species of the genus Neurocaulon (Furcellariaceae, Gigartinales, Rhodophyta) found in the Mediterranean, the Atlantic coasts of the Iberian Peninsula, and the Canary Islands. The gametophytes (having a life cycle with heteromorphic gametophytes and sporophytes) exhibit a highly variable morphology, which historically allowed the distinction of different forms depending on whether they have one or a few large lobes ('grandifolium' form), many small lobes ('reniform' form), or intermediate forms ('intermedia' form).

No previous molecular or in-depth morphological studies have been conducted on the reproductive

structures and post-fertilization stages of these forms to determine whether they belong to the same

species or not. This study aims to conduct a morphological study of the gametophytes of the

'grandifolium' form and will be part of a broader taxonomic study of the genus Neurocaulon in

Europe being carried out at the University of Girona. Special emphasis has been placed on the

description of post-fertilization stages, as the taxonomy of red algae is based on knowledge of these

processes. The methodology used involved studying longitudinal and transverse sections of the

thallus under an optical microscope. The sections were stained with aniline blue or hematoxylin to

highlight the structures. The main result of the study is the complete description of the specimens

of the 'grandifolium' form. Comparing the results with the limited existing data in the literature on

characteristics and reproductive processes suggests that indeed there are several cryptic species of

Neurocaulon in Europe. These species may differ not only morphologically but also in terms of male

reproductive structures (number of spermatangia per mother cell) and post-fertilization stages (starshaped or non-star-shaped gonimoblast and level of protrusion)