Noemí Sánchez

Vegetative and reproductive morphology of Gloiocladia repens (C. Agardh) Sánchez et Rodríguez-Prieto comb. nov. (Rhodymeniales, Rhodophyta), with a taxonomic re-assessment of the genera Fauchea and Gloiocladia

A morphological and molecular study of Fauchea repens, the type species of Fauchea, (Faucheaceae, Rhodymeniales) and its comparison with Gloiocladia furcata, the type species of Gloiocladia, establishes that the two are closely related and belong in the same genus. Accordingly, we propose a new combination, Gloiocladia repens (C. Agardh) Sánchez et Rodríguez-Prieto, comb. nov., for the plant presently known as Fauchea repens (C. Agardh) Montagne et Bory in Montagne and designate a lectotype. We provide an emended description of the genus Gloiocladia, and transfer all the species presently placed in Fauchea to Gloiocladia.

Vegetative and reproductive morphology of the type species of Gloiocladia, G. furcata (Faucheaceae, Rhodophyta)

N. Sánchez and C. Rodríguez-Prieto. 2005. Vegetative and reproductive morphology of the type species of Gloiocladia, G. furcata (Faucheaceae, Rhodophyta). Phycologia 44: 222–233. The type species of Gloiocladia, G. furcata, is described in detail, and its characters are compared with those of other species currently accepted in Gloiocladia. The presence of a subcortex of ovoid, angular or stellate cells, connected by secondary pit connections to form a network parallel to the thallus surface, is confirmed. Female reproductive structures and postfertilization stages are described for the first time. Plants are procarpic, with the 3-celled carpogonial branch and two-celled auxiliary cell branch borne on a cortical cell that acts as supporting cell. The auxiliary cell contains a large proteinaceous inclusion. After fertilisation cells of the carpogonial branch fuse and connect to the auxiliary cell. The auxiliary cell divides into a primary gonimoblast cell that contains the proteinaceous inclusion and a lower auxiliary cell. A fusion cell between the auxiliary mother cell, the lower auxiliary cell and adjacent vegetative cells is formed. Gonimoblasts arising from the primary gonimoblast cell produce several erect projections bearing lobes of ovoid carposporangia. Basal nutritive cells are present, with erect persistent filaments (= tela arachnoidea) surrounding the fertilised procarp and the gonimoblast. Ostiolate cystocarps, with or without horns, arise on branch margins. Spermatangia remain unknown. Tetrasporangia are grouped in slightly raised nemathecia. In the family Faucheaceae, the presence of a subcortex in all individuals and the presence of basal nutritive tissue with erect persistent filaments in fertile female thalli are confirmed to be important taxonomic characters. These observations support the proposal of Norris (1991) to include Gloioderma in Gloiocladia but do not clarify the relationship between Gloiocladia and Fauchea.

Deep-water macroalgal-dominated coastal detritic assemblages on the continental shelf off Mallorca and Menorca (Balearic Islands, Western Mediterranean)

Abstract We present a quantitative physiognomic characterization of major macroalgal-dominated assemblages on coastal detritic bottoms of the continental shelf off Mallorca and Menorca (Balearic Islands, Western Mediterranean). In late spring of 2007 and 2008, 29 samples were collected by bottom trawling at depths between -52 and -93 m. These samples were then sorted and identified to their lowest taxonomic level. Statistical analyses distinguished six different assemblage types: shallower water environments (-52 to -65 m in depth) were characterized by Osmundaria volubilis and Phyllophora crispa meadows and two types of Peyssonnelia beds; two assemblage types, Laminaria rodriguezii beds and maërl beds, were only present in deep-water environments (-77 to -81 m); and an assemblage dominated by P. crispa and Halopteris filicina was found in both shallow and deep waters (-57 to -93 m). We assess the distribution of these six assemblage types through the studied area.

Vegetative, reproductive and molecular characterization of gloiocladia microspora (Faucheaceae, Rhodophyta)

Morphological and molecular studies of Gloiocladia microspora were carried out to confirm its position in the genus Gloiocladia. The thallus is compressed and complanately irregularly branched, and develops narrow, cylindrical segments from the apices, which give rise to new compressed branches in adult specimens. The cortex is composed of an outer section of loose anticlinal filaments, slightly arched at the base, and a single-layered subcortex of cells that form a network parallel to the thallus surface. The medulla is composed of large, longitudinally elongated, hyaline cells. Female gametophytes are procarpic with a three-celled carpogonial branch and a two-celled auxiliary cell branch, both borne on the same subcortical cell. After fertilization, a fusion cell is formed from the auxiliary mother cell, the auxiliary cell, and probably adjacent vegetative cells. Simultaneously the auxiliary cell divides to cut off the primary gonimoblast cell. Components of the mature fusion cell are indiscernible. Nutritive cells and a tela arachnoidea are conspicuous and present at the early procarp stage. Cystocarps are sessile or substipitate, ostiolate, and usually situated around the narrow segments of fronds or, sometimes, on the margins of the compressed branches that arise from narrow segments. Spermatangia are unknown. Tetrasporangia develop in raised nemathecia located on small compressed proliferations or on the narrow segments, and usually surround them. Phylogenetic analyses of partial rbcL sequences resolved G. microspora as a distinct species within the clade of other Gloiocladia species. Vegetative and reproductive morphology, together with molecular analyses support the position of G. microspora within Gloiocladia.

The morphology and reproductive structures of Mediterranean species of the genus Nemastoma J. Agardh, nom. cons. (Nemastomataceae, Nemastomatales): Nemastoma dichotomum and N. dumontioides

Abstract We investigated a collection of Nemastoma J. Agardh, nom. cons. (Nemastomatales, Rhodophyta), including the Mediterranean type material of species described by J. Agardh, Kützing and Ercegovic, and recent specimens from the Mediterranean Sea, Adriatic Sea and northeastern Atlantic Ocean. Based on their habit and vegetative and reproductive structures, we confirm that: (i) all the Mediterranean specimens studied belong to the genus Nemastoma; (ii) two species of Nemastoma co-exist in the Mediterranean Sea: (a) N. dichotomum, which is characterized by great plasticity of habit, a cartilaginous thallus in its basal and middle parts, and presumed reproduction exclusively by apomixis; and (b) N. dumontioides, which is characterized by a regularly pseudodichotomous, saccate-membranous thallus, and which reproduces both sexually and probably apomictically; and (iii) the Atlantic specimens attributed to N. dichotomum belong to other genera, and so, N. dichotomum is probably endemic to the Mediterranean Sea. Thus, three species described by Kützing have been reduced to varieties of Nemastoma dichotomum: (a) var. biasolettianum (Kützing) Rodríguez-Prieto, Verlaque et Vérges comb. nov. et stat. nov., with ligulate upper parts, (b) var. caulescens (Kützing) Rodríguez-Prieto, Verlaque et Vérges comb. nov. et stat. nov., with wedge-shaped upper parts, and (c) var. incrassatum (Kützing) Rodríguez-Prieto, Verlaque et Vérges comb. nov. et stat. nov., with spathulate upper parts. Finally, Nemastoma constrictum and N. constrictum var. longitrichogynum are placed in synonymy with N. dichotomum var. caulescens.

Photoacclimation and photoregulation strategies of Corallina (Corallinales, Rhodophyta) across the NE Atlantic

ABSTRACT This study characterizes the photoacclimation and photoregulation mechanisms that allow calcified macroalgae of the genus Corallina (Corallinales, Rhodophyta) to dominate rock pool habitats across the NE Atlantic despite the highly variable irradiance regimes experienced. Rapid light curves (RLCs) were performed with pulse amplitude modulation (PAM) fluorometry in situ across a full seasonal cycle in the UK intertidal with C. officinalis and C. caespitosa. Latitudinal comparisons were performed across the full extent of C. officinalis’ range in the NE Atlantic (Iceland–northern Spain), and for C. caespitosa in northern Spain. Ex situ RLCs with dark recovery were further employed to assess the optimal, as compared with actual, photophysiology across seasons and latitudes. Corallina species were shown to photoacclimate at seasonal timescales to changing irradiance, increasing light-harvesting during low-light autumn/winter periods and protecting photosystems during high-light summer conditions. Seasonal photoacclimation was achieved through alteration in the number of photosystem (PS) units (PSII and light harvesting antennae) over time. Non-photochemical quenching (NPQ) served as an important photoregulation mechanism utilized by Corallina to prevent or minimize photoinhibition over shorter time scales (seconds–hours), though the efficiency of NPQ was dependent on the seasonal-acclimated state. With increasing latitude the efficiency of photoregulation decreased, representing potential differential photoadaptation of Corallina across species ranges in the NE Atlantic. In contrast, highly conserved inter-specific patterns in photophysiological responses to irradiance were apparent. This study demonstrates the photophysiological mechanisms allowing Corallina to optimize use of the variable irradiance conditions apparent in rock pool environments, when and how they are employed, and their limitations.