The poorly known siphonous green algal genus Pseudoderbesia was originally described from the Caribbean coast of Colombia, and the Canary Islands. Here we describe a collection of Pseudoderbesia from Rhodes, Greece, representing the first report of the genus since its original description in 1991. Cultured plants of Pseudoderbesia were characterized by upright, regularly dichotomously branched siphons, developing from long stolonoid siphons. Molecular phylogenetic analysis based on rbcL and tufA sequences confirmed the placement of Pseudoderbesia in the family Bryopsidaceae, and shows a sister relationship with Bryopsis. Although this is the first record of Pseudoderbesia from the Mediterranean Sea, it is possible that the genus is more widespread and has previously been confused with morphologically similar, but unrelated taxa, such as Pseudochlorodesmis furcellata, or that it has been erroneously attributed to juvenile stages of larger bryopsidalean algae.

Recently, DNA phylogenies resulted in the transfer of some species of the halymeniacean genus Aeodes, namely A. orbitosa and A. ulvoidea, to the genus Pachymenia leaving the former supposedly as a monotypic genus based on the type species, A. nitidissima. Nevertheless, that work overlooked the presence of A. marginata, a red foliaceus alga endemic to the Mediterranean Sea with a convoluted nomenclatural history.

In the present study, we provided a thorough description of A. marginata based on both anatomical and molecular data and inferred its phylogenetic relationships among halymeniacean genera using both chloroplastic (rbcL) and nuclear genes (LSU). Based on our data, A. marginata allied with Halymenia, Cryptonemia, and associated genera rather than with the generitype A. nitidissima, and presented a unique set of characters deserving the status of genus within the Halymeniaceae. Therefore, we proposed the new genus Felicinia based on Felicinia marginata comb. nov.

A description of the multiaxial vegetative of F. marginata construct was provided, highlighting a unique characteristic among red algae: the presence, in the medulla, of peculiar oblique multicellular filaments connecting periclinal filaments. These filaments are produced secondarily as branches from axial filaments and are possibly homologous to the anticlinal filaments observed in the medulla of Halymenia.

A new species of diatom, Orthoseira limnopolarensis, is described from a sediment core in Limnopolar Lake on Livingston Island, South Shetlands in the South Atlantic Ocean. The new species is distinctive in having an array of numerous (12–14) carinoportulae, a number of clearly defined rimoportulae which are described here for the first time in the genus, and a valve face surface that is covered with small, irregularly scattered spines. Linking spines are less well-developed than is generally observed in species of the genus Orthoseira. No caverns or internal undulations are present. Internal valves have not been encountered.

The work presents the morphology of cells and trichomes of Glaucospira laxissima (G.S. West) comb. nova analyzed by light microscopy, confocal laser microscopy (CLM) and transmission electron microscopy (TEM). Cyanobacterial characteristics are confirmed for the first time. It also contains the data on the ecology of this species, found for the first time in Serbia, in a small alkaline lake in a planktic community with the species Cylindrospermopsis raciborskii (Wołoszyńska) Seenayya & Subba Raju, Anabaenopsis elenkinii V.V. Miller and Chrysosporum bergii (Ostenfeld) Zapomělová et al.

An inventory of upper subtidal Cystoseira (0–5 m depth) of the Tunisian coasts (La Galite Archipelago excluded) was carried out from March 2012 to February 2013. Seven Mediterranean endemic taxa new for Tunisia were collected: 4 species, Cystoseira algeriensis, C. barbatula, C. crinitophylla, C. susanensis, and 3 infraspecific taxa, C. compressa f. plana, C. foeniculacea f. latiramosa and f. tenuiramosa. Each taxon is described and their Tunisian range of distribution is given and discussed.

The green alga Dunaliella salina is a common inhabitant of crystallizers in solar saltworks. Although its presence has been associated with low salt quality, little is known about the mechanism through which Dunaliella causes such effect. It has been suggested that the release of organic matter from healthy D. salina cells interferes with NaCl crystallization. With the intention to cast some light on this matter, we grew D. salina cells at different [NaCl] (0.3, 1.0, 2.0 and 3.0 M), in the presence of either NO₃^- or NH4 , in conditions that, although strongly hyperaline, were mild enough to minimize cell lysis and substantial spill over of cytosolic sap. The two N treatments were done because the N-source was shown to influence organic release from D. salina. We then attempted to link this physiological information to the information to the quality of NaCl crystals. In order to reduce the impact of inter-crystal inclusion and focus on the structure of the crystalline reticulum, the volume of water used for the production of crystals was as small as possible. Photosynthesis (as chlorophyll variable fluorescence associated with photosystem II), cell organic (as determined by Fourier Transform Infrared spectroscopy, FTIR) and elemental (measured by total reflection X ray fluorescence spectrometry, TXRF) composition were analyzed at the beginning and in the middle of the exponential growth phase, and in the stationary phase. The quality of the crystals obtained from sterile media and from D. salina growth media was studied by optical microscopy (to determine the shape of the crystals) and by X-ray diffractometry.

Our results demonstrate that the presence of D. salina cells is directly connected to alterations of NaCl crystalline structure (specifically of crystallite size) and with the quantity and quality of contaminants in the salt.

An interest in freshwater red algae began in France over 200 years ago with naturalists, such as Bory de St. Vincent and Sirodot, who described numerous new taxa primarily within the Batrachospermales. Since the late 1800s, there has been limited research on these organisms in France. The present work was undertaken to revisit regions historically known to have a diversity of Batrachospermales. Overall, nine taxa were identified from 22 streams. Nine specimens representing six species were collected from eight streams near Rennes. From the Dax region, 16 specimens of six species were collected from 12 streams. Two streams were sampled near Vernon yielding two species. The rbcL gene was sequenced for all specimens and phylogenetically analyzed. Sequence data revealed that the Batrachospermales were broadly represented by the nine taxa collected. For most taxa, sequence data are available from other parts of the world, but these are the first for Batrachospermum vogesiacum. Although there have been changes in land use, such as road construction, many taxa documented by the pre 20^th century French naturalists are still present in the flora today.