Using three genetic markers (COI-5P, LSU, rbcL), plants historically identified as Platoma cyclocolpum from Bermuda have been linked to Nemastoma gelatinosum from its type locality, each representing a distinct seasonal morphology in the islands. Further, the Bermuda plants are genetically related to the recently described P. chrysymenioides from the Gulf of Mexico. These molecular studies and morphological observations confirm the generic placement of the Bermuda plants in Platoma, necessitating the taxonomic change to the nomenclatural precedent as P. gelatinosum (M. Howe) comb. nov.

Notes sur les algues marines des Bermudes. 12. Évaluation phylogénétique de Nemastoma gelatinosum M. Howe (Rhodophyta, Nemastomatales) de la localité type. L'utilisation de trois marqueurs génétiques (COI-5P, LSU, rbcL) a permis de démontrer la conspécificité de plantes historiquement identifiées comme Platoma cyclocolpum aux Bermudes et un topotype de Nemastoma gelatinosum ; ces deux entités présentant des morphologies saisonnières distinctes dans l'archipel. De plus, les plantes des Bermudes sont génétiquement proches d'un taxon récemment décrit au Golfe du Mexique, P. chrysymenioides. Ces études moléculaires et ces observations morphologiques confirment le placement des plantes des Bermudes au sein du genre Platoma, ce qui nécessite un changement nomenclatural d'où la proposition de P. gelatinosum (M. Howe) comb. nov.

Boergesenia parvula sp. nov. is described from shallow water habitats in Puerto Rico and represents the smallest species of the genus, reaching only 20 mm in height. Recognition of the new entity is supported by molecular sequences of the 18S rRNA gene. Molecular divergence between B. forbesii and the newly described species is 3.4%.

Boergesenia parvula sp. nov. est décrit. Cette espèce vit dans des habitats peu profonds de Puerto Rico et représente la plus petite espèce du genre ne dépassant guère 20 mm de haut. La reconnaissance de ce nouveau taxon est basée sur la séquence moléculaire du gène codant l'ARN 18S. La divergence moléculaire entre B. forbesii et la nouvelle espèce présentée ici est de 3,4 %.

Cymbopleura pyrenaica sp. nov. (Bacillariophyceae) and some other Cymbopleura species rarely observed in some lakes of the French Pyrenees. During a survey of the diatoms from French Pyrenean lakes, a new species of Cymbopleura, Cymbopleura pyrenaica sp. nov. was found. The detailed morphology of this taxon was examined using light and scanning electron microscopy. The new species most closely resembles Cymbella laevis Naegeli, but the absence of apical pore fields places Cymbopleura pyrenaica in the genus Cymbopleura. The most conspicuous ultrastructural feature is the morphological variability of the areolae. Cymbopleura pyrenaica sp. nov. was recorded in several lakes despite its low occurrence and tolerates a wide range of conductivity. A short review of the scarce Cymbopleura species in the investigated lakes was presented.

A new post-fertilisation stage, consisting of secondary connecting filaments produced from the primary connecting filament in the vicinity of the auxiliary cell branch system, was observed in Mediterranean monocarpogonial and polycarpogonial species of Kallymenia. In the monocarpogonial species the connecting filaments were formed from a little modified primary connecting filament close to the auxiliary cell and in the polycarpogonial species they were produced from a highly modified, swollen, hyaline portion of the primary connecting filament that remained attached to the auxiliary cell. Since most of these connecting filaments were seen clearly linked by pit connections in both instances, they are interpreted as secondary connecting filaments produced in essentially the same way as the primary connecting filaments that derive from the carpogonial branch fusion cell.

The first data about the distribution of desmids in Serbia derive from the year 1883 and from that time up to the end of 2010 there were identified 646 different taxa. The species-rich genus Staurastrum is represented with 116 taxa which is about 18% of the total number of desmids in Serbia. Taxa of the genus Staurastrum occur in a large variety of habitats in Serbia, but the greatest diversity was recorded in high mountain peat bogs. In Serbia till now, a large number of taxa of the genus Staurastrum (40.5%) has been found only on one locality (exceptionally rare taxa). In contrast, the species S.alternans, S. gracile, S. orbiculare, S. paradoxum, S. polymorphum and S. tetracerum belong to the most common species in Serbia. In this paper a review is presented of the main taxonomic and ecological characteristics of taxa of the genus Staurastrum, recorded from Serbia.

The first record of the invasive green alga Caulerpa taxifolia in Yolluca Military Base located near Cesmeaalti port (Izmir, Turkey), far away from the other affected areas, is reported, thus reinforcing the hypothesis of anthropogenic dissemination of this alga in the Mediterranean Sea.

This paper describes the distribution and patterns of spread of the red alga Lophocladia lallemandii in the Tuscan Archipelago (NW Mediterranean Sea). Lophocladia lallemandii is recorded from three islands of the archipelago. Invasive traits were only detected at Pianosa Island where the affected stretch of coast has increased from 1.2 km in 2008 to 10.7 km in 2010. The abundance of the alga was found to increase with depth and strong differences among habitats were found in shallow stands. The presence of populations of Cystoseira spp. seemed to facilitate the spread of the alga. In Cystoseira assemblages, the biomass of L. lallemandii could represent up to 44 % of the biomass of Cystoseira spp. and epiphytes. The ability of L. lallemandii to colonize canopy species exposes habitats ecologically important to be invaded, and contradicts the classic concept of ecosystem resistance to biological invasions.

Three alien Rhodophyta, Botryocladia madagascariensis, Hypnea anastomosons and Hypnea valentiae, were recorded and illustrated for the first time from Greece (Aegean Sea and nearby areas). Previously reported from Karpathos Island, B. madagascariensis was observed from Korinthiakos Gulf. Reported as H. esperi from the Mediterranean coast of Israel, H. anastomosans was recorded from the Saronikos Gulf and Rhodes Island. Lastly, the occurrence of H. valentiae in the Eastern Mediterranean basin was confirmed. Habitat, taxonomical comments, and geographical distribution were provided for each species. A critical review of Hypnea species occurring in the Mediterranean Sea was also provided.