Volume 65, Issue 2

Continuous observations of Antarctic benthic diatoms are necessary to detect changes in species composition and biodiversity that may result from environmental changes. The present work provides a systematic list of benthic diatoms from Potter Cove (62.03°S 58.35°W) collected during summer 2015. The new findings are compared with observations made 12 years ago (summer 2003). In total, 80 taxa were found, similar to that encountered earlier, but 17 species (21% of the total species number) were not observed in 2003, and 26 species (31%) of those reported in 2003 did not appear in 2015. The dominant species in 2003 and 2015 was the large epipelic and cosmopolitan Gyrosigma fasciola . Most of the species either newly observed in the present study, or absent in the present study but observed previously, occurred either rarely or very rarely. Gyrosigma arcuatum and Pleurosigma diversestriatum were newly observed in 2015 and not previously reported from polar regions. This study provides systematic and ecological information on all taxa encountered and is illustrated with light microscopy and scanning electron microscopy (SEM) images. We emphasize that ice-inhabiting and other benthic diatoms should be included when considering the biodiversity of polar diatoms. Thus, we hope that the present study will add a piece to the puzzle of climate change effects on the benthic diatoms in this vulnerable region and will complement earlier published species records in the area.

The present study adds 19 species (15 Rhodophyta, one Chlorophyta and three Ochrophyta) to the Azorean marine macroalgal flora, increasing the current total of species recorded in this region to 521 (349 Rhodophyta, 76 Chlorophyta and 96 Ochrophyta), and showing that this isolated island group supports a relatively rich marine macroalgal flora. Some species fall within their known overall distributional range, whereas other found here represent a northern or southern extension to their known distribution in the Atlantic. Three species ( Antithamnionella elegans , Gymnophycus hapsiphorus and Scytosiphon dotyi ) are probable introductions to the Azores, whereas Melanothamnus pseudoforcipatus has an uncertain status. Six of the newly reported species were found as components of the intertidal algal turf samples, which justifies the need for continuing to examine turf samples as new discoveries can be anticipated.

Supralittoral and shallow water seaweed communities are particularly exposed to impacts such as climate change and disturbance by humans. Therefore, their classification, the study of composition, and the monitoring of their structural changes are particularly important. A phytosociological survey of the supralittoral and upper sublittoral vegetation of the South West Baltic Sea revealed eight phytobenthos communities with two variants comprising 35 taxa of macrophytes (18 taxa of Chlorophyta, 13 taxa of Rhodophyta and four taxa of Phaeophyceae, Ochrophyta). Five of the eight communities were dominated by Ulvales ( Ulva intestinalis , Kornmannia leptoderma , and three Blidingia species), the other three by Fucus vesiculosus . Most Fucus vesiculosus -dominated communities contained U. intestinalis and U. linza as subdominants. Only one of the communities had until now been described as an association ( Ulvetum intestinalis  Feldman 1937). The syntaxonomic composition of the investigated vegetation includes both phytocenoses with the domination of green algae ( Ulvetum intestinalis  Feldman 1937 and communities of Blidingia marginata, unidentified Blidingia spp. and Kornmannia leptoderma ), as well as a number of communities dominated by Fucus vesiculosus . Mainly boreal Atlantic species and cosmopolitans make up the bulk of the species in these associations.

The benthic marine algae of the mainland coast of Ecuador are poorly known mainly due to a lack of collections. Currently, DNA barcoding is the preferred method to identify species of benthic marine algae worldwide, as morpho-anatomical characters are inadequate to distinguish many species of macroalgae. We used the red algal barcode rbc L-3P to identify specimens collected in January 2020 from Manabí, Ecuador as Neoizziella asiatica . This is the first member of the red algal order Nemaliales to be reported from the mainland coast of Ecuador and extends the distribution of this alga by 1,100 km to the south from Panama.

The fifth addendum to Schneider and Wynne’s 2007 “A synoptic review of the classification of red algal genera a half century after Kylin’s 1956 ‘ Die Gattungen der Rhodophyceen ’” is presented, covering the names of genus- and higher-level taxa added or modified since our fourth addendum ( Bot. Mar. 62: 355–367). Since the original compilation, we have added 21 new genera in the first addendum, 27 in the second, 40 in the third and 58 in the fourth, demonstrating the increasing amount of genetic work over more than a decade. In this fifth addendum, we add 31 new genera, three new families, two new orders, and one new subphylum from the past three years, as well as listing four genera reinstated from synonymy based upon molecular sequencing studies.