Tubular Ulva species are a prominent component of marine macroalgal communities along the coasts of Taiwan. However, their species diversity remains poorly known. Here, we sequenced and examined collections made over the past 15 years from various habitats in Taiwan. RbcL phylogenetic analyses identified 12 species, and these were largely confirmed by tufA analyses. These included a new species (U. taiwanifretensis sp. nov.), four species recorded for the first time from Taiwan (U. flexuosa subsp. linziformis, U. tepida, U. torta and U. tentaculosa), four undescribed taxa, and three previously reported species [U. arago & euml;nsis (previously recorded as U. linza), U. prolifera, U. meridionalis]. In contrast, three tubular species previously recorded in Taiwan (U. clathrata, U. compressa and U. intestinalis) were not detected in this study. These species may have been misidentified as their tubular morphology superficially resembles that of U. arago & euml;nsis or U. prolifera. Notably, U. taiwanifretensis sp. nov. from the Taiwan Strait is morphologically similar to U. intestinalis.

A basic guide to the requirements of the International Code of Nomenclature for algae, fungi, and plants for the publication of a valid name of new species (and infraspecific taxa) of living algae is provided. It is intended to aid phycologists so that an accurate inventory of the world's algal diversity is achieved. A checklist of actions necessary when preparing for publication of algae names is included.

With 35 currently recognised species, Prasiola Meneghini, 1838 is the largest genus of the family Prasiolaceae (Prasiolales, Trebouxiophyceae). However, recent molecular phylogenetic studies have shown that the genus as currently conceived is polyphyletic, due to a separate genus, Prasiococcus Vischer, clearly being nested between the Prasiola clades. Since the clade containing the type species Prasiola crispa (Lightfoot) K & uuml;tzing has priority, we propose three new taxonomic realignments, based on DNA sequence comparisons, for two clades containing four and two species of Prasiola, respectively, and for another single species. The genus Mariprasiola Heesch, Guiry & Rindi, gen. nov., comprising the four species M. stipitata (Suhr ex Jessen) Heesch, Guiry & Rindi, comb. nov., the type, M. delicata (Setchell & N.L.Gardner) Heesch, Guiry & Rindi, comb. nov., M. linearis (C.-C.Jao) Heesch, Guiry & Rindi, comb. nov. and M. meridionalis (Setchell & N.L.Gardner) Heesch, Guiry & Rindi, comb. nov., distributed in marine habitats. Two species of Vittaprasiola Heesch, Guiry & Rindi, gen. nov., the strictly terrestrial species V. calophylla (Carmichael ex Greville) Heesch, Guiry & Rindi, comb. nov., the type, and the freshwater species V.fluviatilis (Sommerfelt) Heesch, Guiry & Rindi, comb. nov., share a belt-like appearance. Eaprasiola Heesch, Guiry & Rindi, gen. nov. is currently monospecific, with E. japonica (R.Yatabe) Heesch, Guiry & Rindi, comb. nov., found in freshwater habitats in East Asia and with thalli reaching up to 20 cm in length, the largest known representative of the family. Since the remaining 21 species of Prasiola lack genetic data, they cannot at present be assigned to any genus and remain in the genus Prasiola sensu lato.

El reconocimiento de nuevas entidades biológicas y la capacidad de darles un nombre es una tarea intrínseca del taxónomo y contribuye a la construcción de un inventario realista del número de taxones en una flora o región. México y América Latina cuentan con enormes recursos algales, tanto marinos como de agua dulce, y muchos taxones aún están por descubrirse, mientras que otros no han sido publicados por indecisión o falta de herramientas para describirlos. Aquí proporcionamos una guía básica de los requisitos del Código Internacional de Nomenclatura para algas, hongos y plantas para la publicación válida y legítima del nombre de una especie nueva o de rangos infraespecíficos. Esto puede ayudar a los ficólogos de la región a tomar una decisión sobre la publicación de sus nombres nuevos, compartiendo así su experiencia para contar con una idea más precisa de la diversidad actual de algas, en una de las regiones con mayor diversidad ecológica del mundo.

(3024) Dunaliella Teodor. in Beih. Bot. Centralbl., Abt. 1, 18: 230. 1905, nom. cons. prop. Typus: D. salina (Dunal) Teodor. (Haematococcus salinus Dunal). (=) Isomita (Diesing) Diesing in Sitzungsber. Kaiserl. Akad. Wiss., Wien, Math.-Naturwiss. Cl., Abt. 1, 52: 296, 321. 1866 (Monas [unranked] Isomita Diesing, Syst. Helm. 1: 33. 1850), nom. rej. prop. Typus (vide Silva in Regnum Veg. 101: 881. 1979): Monas dunalii Joly (I. dunalii (Joly) Diesing). Isomita was originally proposed by Diesing (Syst. Helm. 1: 33. 1850) as the epithet of an unranked subdivision of Monas O.F. Müll., which he raised to the rank of genus in 1866 (Diesing in Sitzungsber. Kaiserl. Akad. Wiss., Wien, Math.-Naturwiss. Cl., Abt. 1, 52: 296, 321. 1866). In both instances, he included Monas dunalii Joly (Hist. Petit Crustac.: 52. 1840; ≡ I. dunalii (Joly) Diesing, l.c. 1866: 321) and Heteromita angusta Dujard. (Hist. Nat. Zoophyt.: 299, t. 4, fig. 24. 1841; ≡ I. angusta (Dujard.) Diesing, l.c. 1866: 321) as members of the group, the latter as a species inquirenda. Monas dunalii Joly is regarded as a later synonym of Haematococcus salinus Dunal (in Compt. Rend. Hebd. Séances Acad. Sci. 5: 586. 1837), the basionym of Dunaliella salina (Dunal) Teodor., the type of Dunaliella Teodor. (Borowitzka & Siva in J. Appl. Phycol. 19: 567–590. 2007). Joly observed the alga in the salt pans of Villeneuve-lès-Maguelone, near Montpéllier, Hérault, Mediterranean France, the same locality at which Dunal observed the species to which he gave the alternative names, Protococcus salinus, and Haematococcus salinus Dunal (l.c.) (Oren, Saline Syst. 1: 2. 2005). According to Joly (l.c.: 51), he and Dunal visited the locality together on 19 December 1838. Thus, the three names undoubtedly refer to the same organism. While Teodoresco (in Beih. Bot. Centralbl., Abt. 1, 18: 230. 1905) cited both of Dunal's names as synonyms of his newly proposed combination, it appears that Haematococcus salinus has been regarded as the basionym of Dunaliella salina since the creation of the genus. Hamburger (in Arch. Protistenk. 6: 111–130. 1906) stated that she found H. salinus in a sample collected by Ermanno Giglio-Tos from a saltern of Cagliari and sent to her by Otto Bütschli in January of the same year, albeit she later mentioned both Protococcus salinus and H. salinus but only in the historical review of the species. West (in J. Bot. 53: 73–84. 1915) only cited H. salinus as a synonym of D. salina in his note. In the web versions of Index Nominum Genericorum (Farr & Zijlstra, http://botany.si.edu/ing/. 1996–) and Index Nominum Algarum (Silva, https://ucjeps.berkeley.edu/cgi-bin/porp_cgi?556581. 1996–), H. salinus appears as the basionym. Stiles (in Zool. Anz. 25: 694. 1902) wrote regarding the type of Isomita: "Type, probably Monas Dunalii", without lectotypifying it, since this action was not definitely accepted by him, as required by Art. 7.11. The effective lectotypification of the generic name, with the species name that was placed with certainty in it by Diesing, was made by Silva (in Regnum Veg. 101: 881. 1979). This act renders Isomita an earlier taxonomic synonym of Dunaliella. It appears that the genus name has not been employed since. Dunaliella has a wide range of applications (Barbosa & al. in Appl. Phycol. 4: 99–120. 2023). It has been used for basic research in ecotoxicology (Serpa & Calderón in Ecol. Aplic. 4: 127–133. 2006 ("2005"); Wang & al. in Environm. Pollut. 316(1): 120544. 2023), and stress biology (Dai & al. in J. Agric. Food Chem. 71: 17067–17079. 2023; Guermazi & al. in Life 13(2): 313. 2023; Keil & al. in Int. J. Molec. Sci. 24(20): 15374. 2023), for example. It also has industrial applications, since the carotenoids produced by some species are used in pharmacology, food, and cosmetics (Tafreshi & Shariati in J. Appl. Microbiol. 107: 14–35. 2009; Chen & al. in Microbiol. Spectrum 11(2): e04361-22. 2023; Singh & al. in J. Biomolec. Struct. Dynam. 41: 7069–7083. 2023; Zorinc & al. in Bioelectrochem. 150: 108360. 2023; Son & al. in Appl. Microbiol. Biotechnol. 108: 82. 2024), and the capability of some species of the genus to accumulate lipids and starch makes them valuable in biofuel research (Patel & al. in Biomass Convers. Biorefin. 13: 1071–1085. 2021; Gokulnath & al. in Fuel 344: 127981. 2023; Modi & al. in J. Advances Biol. Biotechnol. 26(6): 32–37. 2023). Furthermore, recent research on the biochemical properties found the carotenoids produced by some species may also protect against myocardial ischemia-reperfusion injury (Song & al. in Gene & Protein Dis. 2(2): 387. 2023; Tsai & al. in Int. J. Molec. Sci. 24(4): 3871. 2023), a major complication of cardiac surgery (Frank & al. in Semin. Cardiothorac. Vasc. Anesth. 16: 123–132. 2012). Adopting Isomita would require transfer of over 20 names to the genus (Guiry & Guiry, AlgaeBase https://www.algaebase.org/search/genus/detail/?genus_id=43461. 2024) and would obfuscate essential communication between phycologists and other scientists using strains of the genus for basic and applied research. Thus, in the interest of nomenclatural stability within algal taxonomy and the larger scientific community, we propose the conservation of Dunaliella against Isomita for this commercially important genus of microalgae.

To date (1 November 2023), the online database AlgaeBase has documented 50,589 species of living algae and 10,556 fossil species here referred to four kingdoms (Eubacteria, Chromista, Plantae, and Protozoa), 14 phyla, and 63 classes. The algae are the third most speciose grouping of plant-like organisms after the flowering plants (≈382,000 species) and fungi (≈170,000 species, including lichens) but are the least well defined of all the botanical groupings. Priority is given to phyla and class names that are familiar to phycologists and that are nomenclaturally valid. The most species-rich phylum is the Heterokontophyta to which 18 classes are referred with 21,052 living species and which is dominated by the diatoms in three classes with 18,673 species (16,427 living; 2239 fossil). The next most species-rich phyla are the red algae (7276 living), the green algae (6851 living), the blue-green algae (Cyanobacteria, 5723 living), the charophytes (4950 living, including the Charophyceae, 511 species living, and the Zygnematophyceae, 4335 living species), Dinoflagellata (2956 living, including the Dinophyceae, 2828 extant), and haptophytes (Haptophyta 1722 species, 517 living).

The minute marine multicellular heterokont alga originally described as "Giraudyopsis stellifer" by P.J.L. Dangeard, nom. inval., from Atlantic France, was re-isolated by the germling emergence technique and classified according to psaA and psbC sequences. It is genetically similar (99-100 % identity) to Phaeosaccion multiseriatum R.A. Andersen, L. Graf et H.S. Yoon recently described from the NE Pacific, an ephemeral alga of wide geographical distribution. We isolated it also from substratum samples collected in Korea and the Falkland Islands, where it had not been reported previously. Two isolates of similar morphology from the coast of Chile had the same nuclear ribosomal SSU sequence but differed from P. multiseriatum and P. okellyi R.A. Andersen, L. Graf et H.S. Yoon from New Zealand in psaA and psbC sequences (3-4 % genetic distance). These two isolates are here described as Phaeosaccion westermeieri sp. nov.. Our isolations of P. multiseriatum and P. westermeieri are a further demonstration that the germling emergence technique can reveal microscopic multicellular benthic algae that are easily overlooked in the field.

Cystoseira sensu lato (s.l.) - encompassing the genera Cystoseira sensu stricto (s.s.), Ericaria and Gongolaria - is a diverse group of forest-forming brown macroalgae endemic to the warm-temperate North-east Atlantic. These algae have immense biogeographic and ecological significance and have been experiencing recent regional declines. Most Cystoseira s.l. display important morphological plasticity and can be confused with similar species. Therefore, species boundaries, geographic ranges and phylogenetic affinities remain imprecise for most. In the face of persistent taxonomic difficulties, several authors underlined the necessity for new molecular-based approaches, but studies so far lacked representativity, resolution and standardization. To fill in these gaps, in this study we sequenced a comprehensive collection of Cystoseira s.l. spanning its entire North-east Atlantic range for a similar to 1200 bp cox1 barcode, and sequenced selected individuals representing major genetic entities for a few additional plastid markers. Phylogeographic, phylogenetic and species delimitation methods revealed 27 Molecular Operational Taxonomic Units, including unaccounted cryptic diversity, and elucidated with unprecedented resolution species compositions and phylogenetic relationships within each genus. Some entities within the lineages Cystoseira compressa/humilis, Ericaria brachycarpa/crinita, E selaginoides and tophulose Gongolaria, as well as among free-living algae, conflicted with a priori taxonomic assignments, and required the redefinition, reinstatement and recognition of new taxa. For some, diagnostic mutations and biogeography were more useful for species identifications than morphological characters or conventional barcoding gaps. A few species showed narrow geographic ranges and others were the sole representatives of their respective lineages. Several sister-species showed Atlantic vs Mediterranean complementary ranges. phylogenetic signal of coxl was nevertheless insufficient to confidently determine patterns of lineage splitting in several lineages and species complexes and did not improve significantly with additional plastid markers. We discuss novel systematics and biogeography insights considering the advantages and shortcomings of the barcoding approach employed, and how this comprehensive baseline study can be expanded to address multiple questions still left unanswered.

Until recently, all the bladed members of the Bangiaceae Duby were assigned to the genus Porphyra C.Agardh, nom. cons.; however, in the last twenty years, major molecular taxonomic revisions of this family have resulted in several new and reinstated genera. Porphyra linearis Greville is one of the species retained in Porphyra and its growth and reproduction is confined to the upper intertidal in the colder months of the year. Porphyra hiemalis Kylin was described for specimens collected from the south-west coast of Sweden but was later referred to the synonymy of P. linearis based upon its winter seasonality and linear form. We here compare the morphology and reproduction of isolates of both taxa from various locations in the NE Atlantic, and we sequence the intergenetic RUBISCO spacer and adjacent coding regions in these isolates to verify their phylogenetic relationships with other members of bladed Bangiaceae. Results show that both entities are not only distinct species despite almost identical external morphology, but they belong to different genera. A lectotype and epitype (of sequenced material) is designated for P. hiemalis and a transfer to the reinstated genus Pyropia J.Agardh is proposed as Pyropia hiemalis (Klyin) Varela-Alvarez, Guiry & Serrao, comb. nov.

Freshwater organisms in the Okavango Delta and Lake Ngami (Botswana) provide direct and indirect benefits to people and the economy of the region. However, their existence could be potentially threatened by human activities (primarily, upstream water abstraction and planned hydropower structures) coupled with climate change. For their protection, it is essential to know their distribution, ecology, and status of the ecosystems that they inhabit. Publications that record taxa from the Delta at species level are scarce, particularly aquatic macroinvertebrates. Identifying organisms to species level can provide more accurate information for environmental monitoring and conservation programmes but requires significant training and expertise. Here, we present a comprehensive taxonomical review of 2204 freshwater species from the Okavango Delta and Lake Ngami, with additional 355 species found in other areas of Botswana that are likely to be present in the study region. We also compare the diversity of the Okavango Delta and Lake Ngami with two other tropical wetlands: the Pantanal (Brazil) and the Kakadu Region (Australia). We show that biodiversity in the Okavango Delta and Lake Ngami is higher than in previous estimates, with recorded species richness dominated by phytoplankton and macroinvertebrates. Most species are widespread across the system and southern Africa. The resulting database includes new records (Bryozoa, Porifera), information on species conservation status, habitat, ecology, distribution in continental Africa, site details and taxonomical notes. This will be an essential resource for researchers, conservation managers, policy makers and consultants investigating freshwater biodiversity in tropical wetlands in the region.

Dataset with 2,200 freshwater species from the Okavango Delta and Lake Ngami (Botswana), with additional 349 species found in other areas of Botswana that are likely to be present in the study region. The dataset covers the following groups: amphibians, birds, fishes, macroinvertebrates, macrophytes, mammals, reptiles, phytoplankton, and zooplankton. The following information is given for each species: status in the Okavango Delta and Lake Ngami (present/potentially present); conservation status globally, Phylum, Class, Order, Family, Genus, species name, cited synonyms, common name, habitat, presence in high water, presence in low water, ecology, distribution in continental Africa, confirmed locations in the Okavango Delta, site coordinates, references, notes.

This updated list is composed of a total of 661 records, which includes 71 brown algae, 450 red algae, 137 green algae, and three seagrasses, with an overall rate of endemism of 13.2%. Almost half (46.7%) of the Hawaiian records presented here are represented by at least one DNA sequence, while 16.3% are confirmed through a DNA sequence match to a topotype, and 6.7% are confirmed through a DNA sequence match to a type specimen. The data are presented in the context of the natural history of the Hawaiian Islands, which is heavily influenced by the volcanic hotspot origin of the archipelago in the middle of the Pacific Ocean, as well as the important cultural role of seaweeds and other marine plants in Hawai'i, and the current threats to marine ecosystems, which include the introduction and proliferation of a number of invasive marine macroalgae.

Taxonomic, nomenclatural and distributional changes since the publication of the 2011 edition (reprinted 2021) of The Freshwater Algal Flora of the British Isles ("Flora") are reviewed together with some changes overlooked earlier. Many of the more recent changes are a result of studies combining an analysis of morphological and DNA sequence data. Of the 473 changes reported most concern the Chlorophyta (131) and the Charophyta (156) followed by the Cyanobacteria (101), with most of the alterations to the Charophyta involving the desmids (136). Also included are 83 new additions to the British and Irish freshwater algal floras, including 20 overlooked in the Flora. Most of these additions are new records: four are newly described desmids and Synura hibernica (Ochrophyta, Chrysophyceae, Synurales) and Chlorococcum turfosum (Chlorophyta, Chlorophyceae, Chlamydomonadales) are also new. The new additions to Flora include information on locality, collector and publication source. Reference is made to discussions in the Flora giving reasons why some genera and species combinations were not accepted, particularly concerning the Cyanobacteria for which a relatively conservative approach had been adopted in the previous edition of the Flora.

The genus Porphyra sensu lato (Bangiaceae, Rhodophyta), an important seaweed grown in aquaculture, is the most genetically diverse group of the Class Bangiophyceae, but has poorly understood genetic variability linked to complex evolutionary processes. Genetic studies in the last decades have largely focused on resolving gene phylogenies; however, there is little information on historical population biogeography, structure and gene flow in the Bangiaceae, probably due to their cryptic nature, chimerism and polyploidy, which render analyses challenging. This study aims to understand biogeographic population structure in the two abundant Porphyra species in the Northeast Atlantic: Porphyra dioica (a dioecious annual) and Porphyra linearis (protandrous hermaphroditic winter annual), occupying distinct niches (seasonality and position on the shore). Here, we present a large-scale biogeographic genetic analysis across their distribution in the Northeast Atlantic, using 10 microsatellites and cpDNA as genetic markers and integrating chimerism and polyploidy, including simulations considering alleles derived from different ploidy levels and/or from different genotypes within the chimeric blade. For P. linearis, both markers revealed strong genetic differentiation of north-central eastern Atlantic populations (from Iceland to the Basque region of Northeast Iberia) vs. southern populations (Galicia in Northwest Iberia, and Portugal), with higher genetic diversity in the south vs. a northern homogenous low diversity. For. P. dioica, microsatellite analyses also revealed two genetic regions, but with weaker differentiation, and cpDNA revealed little structure with all the haplotypes mixed across its distribution. The southern cluster in P. linearis also included introgressed individuals with cpDNA from P. dioica and a winter form of P. dioica occurred spatially intermixed with P. linearis. This third entity had a similar morphology and seasonality as P. linearis but genomes (either nuclear or chloroplast) from P. dioica. We hypothesize a northward colonization from southern Europe (where the ancestral populations reside and host most of the gene pool of these species). In P. linearis recently established populations colonized the north resulting in homogeneous low diversity, whereas for P. dioica the signature of this colonization is not as obvious due to hypothetical higher gene flow among populations, possibly linked to its reproductive biology and annual life history.

Geologically recent radiations can shed light on speciation processes, but incomplete lineage sorting and introgressive gene flow render accurate evolutionary reconstruction and interpretation challenging. Independently evolving metapopulations of low dispersal taxa may provide an additional level of phylogeographic information, given sufficiently broad sampling and genome-wide sequencing. Evolution in the marine brown algal genus Fucus in the south-eastern North Atlantic was shaped by Quaternary climate-driven range shifts. Over this timescale, divergence and speciation occurred against a background of expansion-contraction cycles from multiple refugia, together with mating-system shifts from outcrossing (dioecy) to selfing hermaphroditism. We tested the hypothesis that peripheral isolation of range edge (dioecious) F. vesiculosus led to parapatric speciation and radiation of hermaphrodite lineages. Species tree methods using 876 single-copy nuclear genes and extensive geographic coverage produced conflicting topologies with respect to geographic clades of F. vesiculosus. All methods, however, revealed a new and early diverging hermaphrodite species, Fucus macroguiryi sp. nov. Both the multispecies coalescent and polymorphism-aware models (in contrast to concatenation) support sequential paraphyly in F. vesiculosus resulting from distinct evolutionary processes. Our results support (1) peripheral isolation of the southern F. vesiculosus clade prior to parapatric speciation and radiation of hermaphrodite lineages-a "low-latitude species pump". (2) Directional introgressive gene flow into F. vesiculosus around the present-day secondary contact zone (sympatric-allopatric boundary) between dioecious/hermaphrodite lineages as hermaphrodites expanded northwards, supported by concordance analysis and statistical tests of introgression. (3) Species boundaries in the extensive sympatric range are probably maintained by reproductive system (selfing in hermaphrodites) and reinforcement.

The taxonomy of the genera Grateloupia, Phyllymenia, and Prionitis has been revised several times but remains controversial. The anatomy of female reproductive structures in combination with phylogenetic reconstructions is mostly used to define the genera. However, the architecture and behavior of the auxiliary cell ampullae before and after diploidization are not well documented for most species. To fill this knowledge gap, we examined the female reproductive structures of a new species (Prionitis taiwani-borealis sp. nov.) from Taiwan and compared our observations to the species currently placed in the Phyllymenia/Prionitis complex. The female reproductive structures of the Phyllymenia/Prionitis complex are characterized by (1) 2-celled carpogonial branches with the supporting cell being the basal cell of a third-order ampullar filament; (2) auxiliary cell ampullae composed of three orders of unbranched ampullar filaments before diploidization; (3) cells of auxiliary cell ampullar filaments forming a cellular cluster after diploidization and surrounding the developing gonimoblasts; (4) gonimoblast initials produced from the diploidized auxiliary cells before fusing with them; and (5) branched auxiliary cell ampullar and secondary medullary filaments involved in early pericarp formation. A monophyletic relationship of species possessing female structures similar to those of Pr. taiwani-borealis and related species was highly supported based on combined rbcL and LSU rDNA sequence analyses. The female reproductive structures of other species of Grateloupia sensu lato, phylogenetically closely related to the Prionitis and Phyllymenia assemblage, require reinvestigation as correct interpretations of pre- and post-fertilization events have proven to be informative for resolving the systematics of the Halymeniaceae.

Sea Lettuce (Ulva spp. Ulvophyceae, Ulvaceae) has tremendous ecological and industrial impacts, from the negative effects of green tide events to the industrial production of food, feed, and value-added products. Due to the morphological similarities between Ulva species, their identification requires the use of "barcoding", which relies on the sequencing of short fragments of DNA and the comparison of the obtained sequence to that of sequences present in public repositories. However, Sanger sequencing can be costly when hundreds of samples need to be analysed. In addition, "barcoding", which uses Sanger sequencing, cannot be applied directly on bulk biomass, and requires independent assessment of the individuals within, which is often not possible in commercial products. Here, we describe a novel "sequencing-free" method for species identification of foliose Ulva species that by-passes the drawbacks associated with Sanger sequencing. The assay uses restriction digestion enzymes which target species-specific Single Nucleotide Polymorphisms (SNPs) present within the ITS1 sequence. Digestion of the ITS1 PCR product with two enzyme mixtures allows for the discrimination of the main foliose Ulva species, as well as U. compressa, which can have a foliose morphotype. Of the species tested, only U. pseudorotundata and U. arasakii show the same digestion pattern. Since those two Ulva species are allopatric, we expect this issue to be of limited impact for the users. In addition to species identification, we demonstrate that the assay can be used for hybrid detection, which can have interests for Ulva breeding and species delimitation. Importantly, the assay can be used to detect at once the different Ulva species present within a bulk of Ulva biomass, which could allow for traceability and characterisation of the purity of Ulva commercial products. This study provides a new quick and cost-effective method for foliose Ulva species identification that could readily be extended to other species.