Band 66, Heft 3

Non-indigenous seaweed species have been introduced to the coasts of Brittany, France for decades, with an increasing arrival rate since the 1970s due to both the introduction of the Pacific oyster and increased maritime traffic. In this study, seven species of red macroalgae originating from the Pacific Ocean were found in new locations around the coasts of Brittany between 2018 and 2022. The seaweed species belong to four different orders: Ceramiales ( Antithamnion hubbsii , Polysiphonia morrowii , and Symphyocladiella dendroidea ), Halymeniales (including Pachymeniopsis lanceolata and Polyopes lancifolius ), Rhodymeniales ( Botryocladia wrightii ), and Gigartinales ( Solieria sp.). The dispersal mode and putative invasive potential of each species were examined, and the species were described in terms of their macroscopic and microscopic appearance and habitat. These finds result from a combination of citizen science and long-term monitoring. Used together, these two approaches can aid in the detection of these species on other European coasts and in understanding their dispersion.

Morphological variability is common among macroalgae. In central Chile, Mazzaella laminarioides extends throughout the intertidal rocky zones, where blades are reported to grow up to 20 cm in length. Nevertheless, in low rocky intertidal zones with sand-influence, blades are noticeably larger than in other shores without sand effect. The aim of this study was to compare the morphology of M. laminarioides blades from two different conditions. Blades collected from four sites with, and four without, sand-influence were evaluated with traditional morphometry. Results showed that blades were longer and wider in sand-influenced sites. Sand abrasion was not directly evaluated, but indirect effects such as the abundance of bare rock and of sand tolerant species were higher in areas with sand-influence. Also, long blades were restricted to sand-influenced sites, supporting the relation between these two variables. Molecular analyses using the COI marker confirmed large-bladed individuals as M. laminarioides . Results indicated that life cycle phase, seasonality and vertical height were not related to large blades. We suggest that restriction of large blades to sand-influenced sites may be related to the healing processes of basal holdfasts after suffering sand abrasion.

Marine epiphyte studies in Mexico, including macroalgae, are lacking in the published literature. Floristic studies have been mainly focused on identifying the algae growing on rocky substrata, and epiphytic algae have been recorded, but only occasionally. The aim of this work is to establish the current state of knowledge of the epiphytic macroalgae and their hosts on the Mexican coasts. A systematic revision of the literature published from 1950 to 2021 is also reported, the literature information is included, and the composition, species richness, current state of knowledge of the epiphytic marine macroalgae, and their relationship with the various marine Mexican ecoregions are reported. Sixty-one publications since 1950 included at least one record of epiphytic macroalgae. In this study, 615 species of epiphytic macroalgae and 224 species of hosts for Mexico are reported. This checklist will provide a baseline for future taxonomic and biogeographic studies of the epiphytic marine algae in the country.

The Gracilariaceae are important in the biotechnology industry and microbiology research. Some Gracilaria species are difficult to identify morphologically and molecular phylogenetic data hold a key role in species level identification. In this study, the chloroplast genomes of G. changii and G. salicornia from the Peninsular Malaysia were sequenced to compare with the published taxa in order to gain a better understanding of the phylogenetic questions regarding the red algae, particularly G. changii and G. firma . Phylogenetic analysis for 66 plastid genes showed that G. changii from Malaysia formed a sister lineage with G. firma with a genetic distance of 0.43 %. However, there was a genetic distance of p  = 4.32 % between the Malaysian and Philippine samples of G. changii , indicating they are genetically distinct. Five chloroplast genes ( pet F, rps 12, rps 14, rpl 18 and pet B) showed higher variation of genetic distance between Malaysian G. changii and G. firma ( p  = 1.23–2.00 %) and the intraspecific variation in G. salicornia from Peninsular Malaysia and Hawaii varies from p  = 0–0.31 %. The lack of overlap between the intraspecific genetic distance of Malaysian G. changii and interspecific genetic distance of Malaysian G. changii-G. firma indicates that G. changii and G. firma are not conspecific.

Four species of Erythrotrichia ( E. biseriata , E. reflexa , E. tetraseriata , E. carnea ) have been reported in Korea, but phylogenetic studies have not been conducted on them. We analyzed two newly collected Erythrotrichia isolates using rbc L DNA sequences and determined their species status using four DNA-based species delimitation methods. One isolate (KNU-1) grouped with E. carnea in three methods: Assemble Species by Automatic Partitioning, both single-threshold and multiple-threshold general mixed yule coalescent, but grouped as a distinct species in the statistical parsimony network analysis. A second isolate (KNU-2) was considered a distinct species in all the above species-delimitation methods. We propose the name, Erythrotrichia johnawestii sp. nov., for this new species. The new species was different from E. carnea in lacking a thick outer cell wall layer and with a smaller cell size. Mature monosporangia produced raised openings that released monospores. Cell walls were not detected in newly released monospores but began to appear when the spore attached to the substratum and produced rhizoids. Sexual reproduction was not observed during the four-year culture period.