Elasmobranchii, including sharks, rays, and skates, face increasing threats from overfishing and habitat degradation, particularly in regions with limited monitoring and management. The present study used DNA barcoding to investigate the mitochondrial haplotype diversity and phylogenetic relationships of elasmobranch species from daily fish landings in the coastal area of Pakistan. Our findings provide baseline DNA barcode data and preliminary insights into mitochondrial variation of Chiloscyllium burmense, Iago omanensis, Carcharhinus sorrah, Rhizoprionodon oligolinx, Rhizoprionodon acutus, Scoliodon laticaudus, and the Critically Endangered species, Rhina ancylostoma and Glaucostegus typus. A clear barcode gap (5.91
Sublittoral rocky habitats host a diversity of Mediterranean biocoenoses included as habitats of special conservation interest due to their increased biodiversity and vulnerability. However, these habitats have seldom been investigated in the eastern Mediterranean. Habitat types and biodiversity gradients of megabenthic species along the rocky sublittoral cliff of the Rodopos peninsula (NW Cretan Sea, South Aegean, eastern Mediterranean) were studied in autumn 2014 using non-destructive techniques. Visual records were made by diving in 13 sampling stations, randomly dispersed along the main geomorphological sub-areas of the cliff, from the surface down to 40 m depth. At each station, the diversity and relative abundance of epibenthic organisms were assessed along two replicate belt transects (2 × 5 m), each divided into 125 quadrats, using the ACFOR scale. Photoquadrats were used to estimate the percentage of megabenthic species coverage through image analysis. Additionally, underwater surveys (26 dives of approximately an hour each) along vertical strip transects (2 m wide) were carried out to assess the typology of benthic habitats and biocoenoses using underwater video records (390 min). Up to eight different biocoenoses were recorded according to the EUNIS categorization system, classified into four Mediterranean habitats. A total of 119 megabenthic taxa were identified, some of them showing partial or full necrosis. Several species and habitats of conservation priority and interest were also documented during the survey. Biodiversity was higher at the peninsula’s edge, especially in deeper and cavernous habitats. Megabenthic community structure varied spatially along the cliff, likely influenced by geomorphology and fisheries. The results highlight the need for establishing conservation actions and management planning to sustain marine biodiversity based on appropriate monitoring.
Comau Fjord, in northern Chilean Patagonia, harbors subtidal biodiversity shaped by strong environmental gradients and growing anthropogenic pressure. This study characterized the composition and structure of subtidal epibenthic assemblages, including benthic invertebrates, fishes, and macroalgae, in shallow rocky habitats in the inner and outer sectors of Comau and Cahuelmó fjords, providing an initial assessment of the ecological role of the habitat-forming species Aulacomya atra. Nondestructive methods were employed, including photo-quadrats and visual census surveys. A total of 71 megabenthic invertebrate taxa were recorded. A. atra was the most representative mollusk, forming dense aggregations in the inner fjord. However, its abundance showed negative (nonsignificant) correlations with species diversity and evenness, not supporting the expectation that mussel beds behave as “animal forests” enhancing biodiversity and suggesting a potential dominance effect; Crepidula sp. and actiniarians dominated outer fjord sites. Macroalgal richness reached 14 species, with Macrocystis pyrifera observed only in exposed zones. Crustose algae of the genus Lithothamnion were most frequent. The occurrence of A. atra was positively correlated with macroalgal cover, particularly where Lithothamnion spp. were common. Eight fish species were identified, with Pinguipes chilensis and Sebastes oculatus being the most frequent. Greater fish richness and abundance occurred at inner fjord stations, with diversity positively correlated with temperature, pH, and dissolved oxygen. Multivariate analyses revealed no significant differences in community composition between inner and outer sites or between areas with and without A. atra beds. These findings highlight the need to better understand habitat-forming species in shallow estuarine environments.
The present work resolved the taxonomic identity of Cirrata sp. A beaks by demonstrating that these beaks correspond to those of the large deep-sea cirrate Inopinoteuthis magna (Hoyle, 1885). Synonymization resulted from the comparison of Cirrata sp. A beaks with those from a new specimen of I. magna that was identified both morphologically and genetically. The specimen was sorted from a stomach of a Patagonian toothfish that was caught in Kerguelen waters. A review of the existing literature on I. magna listed 18 specimens, and the synonymization of Cirrata sp. A with I. magna adds a further eight records, for a total of 26 known individuals. Most specimens were collected in two hot spots, the Northern Atlantic and Southern Ocean (where the holotype was caught). The present study illustrates the usefulness of using different means (specimens’ morphology and anatomy, DNA analysis, beak morphology) that complement each other to disentangle and clarify taxonomic issues.
The Kuroshio Current acts as both a dispersal pathway and a biogeographic barrier for marine and diadromous species in the western Pacific. Lateolabrax latus, a temperate species that utilizes river environments in its larval and/or juvenile stages, is commonly found around mainland Japan but has rarely been recorded in the subtropical Ryukyu Archipelago. In the present study, we report the first confirmed specimen of L. latus from the Kita-daitō-jima Island, which is located south of the Kuroshio Current and lacks freshwater systems. To investigate the origin and life history of this individual, we conducted morphological identification and otolith microchemical analyses, including Sr/Ca ratio profiling and annual ring counts. The sagittal otolith exhibited ten distinct opaque bands, indicating an estimated age of 10 years. The Sr/Ca profile suggests that the individual hatched in a marine environment and spent several months in freshwater or brackish water during its early life before transitioning to a fully marine habitat. Given the absence of suitable freshwater habitats on the Kita-daitō-jima and nearby islands, and the lack of local reproductive populations, the individual was likely transported from the Japanese mainland or the Yaku-shima Island via the Kuroshio Countercurrent. This finding provides new insights into the long-distance dispersal potential of L. latus and highlights the ecological role of oceanic currents in shaping species distributions beyond the typical range.
The East Asian brackish-marine taxon Bicornucythere bisanensis (Okubo, 1975) is reported live from the Tagus River, Portugal, apparently transported live in ships’ ballast water, and believed not to occur between Asia and Europe. The morphology, lifestyle, ecology and occurrence pattern of B. bisanensis are well-documented; however, a background systematic problem is discussed. Natural and anthropogenic dispersal of exotic marine and nonmarine ostracods is reviewed.
To improve our understanding of the diversity of Korean sand-burrowing amphipods, we conducted a taxonomic assessment of an undescribed phoxocephalid species together with a population genetic analysis of the dogielinotid amphipod Haustorioides koreanus. Here, we describe a new sand-burrowing amphipod, Grandifoxus donghaensis sp. nov., from the East Sea of South Korea. This species can be distinguished from its congeners by a combination of morphological characteristics, including a long rostrum, absence of facial spine on the merus of pereopod 6, presence of a row of facial setae on urosomite 1, marginal spines on the inner ramus of uropod 2, and two dorso-lateral spines on each telson lobe. Partial gene sequences of the mitochondrial cytochrome c oxidase subunit I (COI) of the new species were determined and an identification key to the genus is provided. The COI sequences of Haustorioides koreanus populations from the Yellow Sea and the East Sea were analyzed. Comparative analysis of COI haplotypes demonstrated a clear genetic differentiation between the two regions. This genetic break may reflect limited dispersal due to the species’ fossorial behavior or an oceanographic separation between the Yellow Sea and East Sea, possibly linked to the Korea Strait.
Invertebrates are key components of coastal ecosystems, yet their diversity and distribution in the Baltic Sea often remain poorly resolved due to methodological constraints. This study employed environmental DNA (eDNA) metabarcoding of the 18S rRNA gene to characterise invertebrate assemblages from nine water samples (depths < 0.5 m) collected at three coastal sites around Gotland, Sweden, in summer 2021. Sequencing yielded 506,424 high-quality reads representing 42 invertebrate taxa across eight phyla. Arthropoda dominated both taxon richness and sequence abundance, with the copepod Acartia (Acanthacartia) tonsa detected in nearly all samples. Alpha diversity metrics indicated low to moderate richness (8–18 taxa per sample), with some spatial differentiation among sites. Principal coordinate analysis based on Jaccard dissimilarities explained 57.5 https://www.phylopic.org/ .
Bathynomus sampadae sp. nov., from 970 − 1049 m depth off the southeast coast of the Andaman Islands, Andaman Sea, the first record of the genus from Andaman waters, is described and illustrated. The new species, 14 to 17 cm in length, belongs to the ‘supergiant’ group of species and is distinguished by the pleotelson being 0.8 times as long as anterior width, with a granular dorsal surface and a conspicuous longitudinal carina running the entire length; the posterior margin has 7 long, upwardly, curved, prominent cylindrical spines along distal margin, and two small lateral spines; the inter-spinal margin is concave and setose, the uropodal exopod lateral margin is convex, with 10 robust setae, and a continuous setal fringe of medium length (69
Taxa defined through Molecular Parataxonomy are taxon inquirendum that require assessment of defining features before its hypotheses become useful or discredited within the existing taxonomic system. In the cnidarian order Zoanthidea, these parataxonomic definitions paired with gross anatomical features are irreconcilable with historical taxa at the family level and below. Here, we revise genera Kulamanamana, Zibrowius, Hurlizoanthus, Kauluzoanthus, and Bullagummizoanthus and their type species to include diagnostic characters accessible only via serial histological examination of microanatomy. Each genus was found to exhibit cyclically transitional marginal musculature arrangements which are diagnostic of Gerardiidae. This revision bridges the parataxonomic gap created by definitions based on barcodes, provides characters that are more accessible to researchers and historical specimens, contributes to our understanding on the evolution of form, verifies and revises existing taxa while addressing an ongoing debate about intrafamilial partitions of Parazoanthidae. This contribution supports the retention of Gerardiidae and erects families Antipathozoanthidae fam. nov. and Vitrumanthidae fam. nov., while suppressing three families for inconsistencies with phylogeny and ICZN nomenclature rules, and one order-level nomen for being unavailable for the entire history of its usage.
A new species of the rare marine nematode genus Lauratonemella, Lauratonemella bharatensis sp. nov., is described from intertidal sandy sediments of the Gopalpur coast, eastern India. This represents the first record of the family Lauratonematidae from Indian waters and the second described valid species of the genus. Morphologically, the new species is distinguished from its congener by the absence of a gubernacular apophysis and the presence of a single precloacal supplement in males. These diagnostic features necessitate emended diagnoses of both the family Lauratonematidae and the genus Lauratonemella. Field emission scanning electron microscopy (FESEM) is applied here for the first time to this genus to investigate its ultramorphology. In addition, this study provides the first molecular characterization of Lauratonemella, enabling an assessment of its systematic position using phylogenetic analyses. Bayesian inference based on SSU and LSU gene sequences was analysed to estimate the phylogenetic relationship of the family Lauratonematidae within the order Enoplida. Overall, this integrative approach underscores the need to reassess the systematic placement of Lauratonematidae using additional molecular markers and expanded species representation.
The amphipod genus Eriopisella Chevreux, 1920 is a cosmopolitan genus that currently includes nine recognized species. Here, we described Eriopisella diupila sp. nov. from material collected in Motril (S E Iberian Peninsula, North Alboran Sea), mainly characterized by the presence of a very large distolateral robust seta in the endopodite of the first uropod, reaching more than three-quarters of the endopodite length. This species represents the second record of this genus for the Mediterranean Sea after E. ruffoi, but both species differ in the marginal robust setae in both rami of the first uropod and the large distolateral robust setae in the endopodite of this appendage, both characters present in E. diupila sp. nov. but lacking in E. ruffoi. Additionally, type species of the genus, E. pusilla, is redescribed from Atlantic France to correct a confusing discrepancy in the original description. Each constituent species of the genus was re-examined from the literature, including the illustrations of the main characters, which led to the proposal to transfer the species Madapisella madagascarensis back to the genus Eriopisella, thereby raising the number of valid species to 11. A dichotomous key to the world Eriopisella species is provided.
Polychaetes are a dominant and functionally diverse infaunal group of marine soft-bottom ecosystems. Yet their diversity in the Weddell Sea remains poorly known. We investigated the composition of polychaete communities (taxonomic and functional identity) in two key regions: Antarctic Peninsula and Filchner Trough region. Sediment cores collected during three RV Polarstern expeditions (PS81, 96, 118), revealed 1,605 polychaete individuals from 34 families. We assigned them into 14 functional groups, based on their feeding, motility and movement type. Polychaete abundances were highest in the northwestern Weddell Sea and lowest at the deeper Filchner Trough sites. Across all sites, Paraonidae and Cirratulidae were the dominant families, while motile burrowing subsurface deposit feeders prevailed functionally. Cluster analyses distinguished six taxonomic and five functional community types, indicating heterogeneous community structures. Regional patterns were evident with Hesionidae, Opheliidae and Maldanidae more abundant around the Antarctic Peninsula, while Syllidae, Glyceridae and Lumbrineridae in the Filchner Trough region, underlining different ecological roles under different environmental conditions. Our results highlight the spatial variation of polychaete communities and emphasize the need to integrate taxonomic and functional perspectives to comprehensively assess the different facets of biodiversity and to support conservation efforts for vulnerable Weddell Sea ecosystems.
The molecular operational taxonomic unit (MOTU) Macrostylis sp. ML08 was particularly abundant in samples from the abyssal depths of the Vema Fracture Zone (VFZ) in the Atlantic Ocean. This MOTU exhibited an extensive distribution spanning thousands of kilometers across the Mid-Atlantic Ridge and was common and abundant in samples from the eastern VFZ, but rare in samples from the western VFZ. An earlier phylogenetic reconstruction based on 16S mitochondrial DNA (mtDNA) identified M. ML08 as a potential species complex. The present study used an integrative approach combining molecular genetics and geometric morphometrics to show that M. ML08 is a species complex comprising seven new species. The M. ML08 species complex is further characterized by extreme sexual dimorphism.
Actinostella flosculifera (Le Sueur, 1817) is a common species of sea anemone in the tropical Atlantic’s coastal and reef ecosystems, with records ranging from Bermuda Islands to Brazil, and from some areas of the Eastern Atlantic. Actinostella flosculifera exhibits wide morphological variability, mainly in terms of coloration patterns and a range of different sizes. We conducted a morphological and genetic study of this species using specimens collected from several localities in the Caribbean Sea, the Gulf of Mexico, and Brazil. We also examined specimens previously deposited in the National Museum of Natural History at the Smithsonian Institution, and compared our data with previous studies on A. flosculifera, as well as with other species of Actinostella, such as A. bradleyi and A. californica from the Eastern Pacific. The results of phylogenetic analyses, based on molecular data from two nuclear and three mitochondrial markers, revealed the existence of two subclades of Actinostella in the western Atlantic. Based on combined molecular and morphological evidence, one of these subclades is herein recognized as a distinct species and described as Actinostella yucatanensis sp. nov., found on Chabihau beach, Yucatán Peninsula, Mexico. We provide a detailed description of A. yucatanensis sp. nov., including images of its external and internal anatomy, cnidome and capsule size ranges and distribution, and a molecular diagnosis. In addition, we present an updated description of A. flosculifera and document for the first time the presence of small pore-shaped apertures (similar to cinclides) on the marginal ruff.
Cryptic diversity in mesopelagic fish is increasingly documented across the Indo-Pacific, but remains understudied in the Red Sea, a region known for its high endemism and unique ecological conditions. We investigated cryptic diversity in Benthosema spp. and population genetic structure in the two most abundant mesopelagic fishes in the eastern Red Sea, the Benthosema pterotum species complex and the endemic Vinciguerria mabahiss. Using concatenated mitochondrial (12S, 16S, and COI) sequences from 275 V. mabahiss and 84 Benthosema specimens, we detected panmictic populations in both species. Both species showed high haplotype diversity and signatures of recent demographic expansion, supported by star-like haplotype networks, negative neutrality tests, and Bayesian skyline plots. Phylogenetic analysis revealed a cryptic lineage (Benthosema cf. pterotum) in the eastern Red Sea, forming a sister lineage within the genus. Its genetic similarity with Gulf of Oman populations suggests ongoing gene flow through the Strait of Bab-el-Mandeb. These findings challenge current taxonomic frameworks and highlight the importance of accurate species delimitation for biodiversity monitoring and fisheries management. High genetic connectivity and demographic expansion in both mesopelagic fish species suggest resilience driven by large effective population sizes and high dispersal potential. These results provide the first population genetic baseline for the largest fish stock in the eastern Red Sea and support future efforts to assess adaptive potential in a warming marginal sea.
The genus Bathyporeiapus Schellenberg, 1931, includes three intertidal amphipod species present in the southern region of South America: Bathyporeiapus bisetosus Escofet, 1970, and B. ruffoi Escofet, 1971, in the Atlantic waters and B. magellanicus Schellenberg, 1931, in the Pacific. Bathyporeiapus taxonomy is understudied, with records mainly from general intertidal fauna inventories. In this context, the present study provides a redescription of B. magellanicus and B. ruffoi, with comments on morphology of B. bisetosus. The type material of B. magellanicus, B. bisetosus, and B. ruffoi was analyzed, and new specimens of B. bisetosus and B. ruffoi were collected in the intertidal zone of the São Paulo and Rio Grande do Sul state, southern Brazil. Species differ in the number of T-setae on peduncle article 3 of antenna 2: B. magellanicus (3), B. bisetosus (2), and B. ruffoi (4), and in the number of articles on pereopod 7 dactylus: B. bisetosus (5–8), B. magellanicus (8–10), and B. ruffoi (14); also, B. magellanicus presents maxilla 1 with setae on the inner plate. Furthermore, the males of Bathyporeiapus species are not known, and in the present study, more than a thousand female and juvenile individuals were collected, but not males, reinforcing the need for studies on life history. An identification key for the three known species of Bathyporeiapus is given.
Identifying and monitoring nursery habitats is crucial for shark conservation, especially for species threatened with extinction. The aim of this study was to explore inter- and intra-annual changes (between 2016 and 2025) in the abundance, size, and sex ratio of the poorly studied, endemic, and endangered Atlantic weasel shark (Paragaleus pectoralis) in the nursery of Sal Rei Bay (Boa Vista Island, Cabo Verde) and investigate how such changes relate to local environmental conditions. From 2016 to 2025, 150 individuals were sampled (71 females and 79 males) with total length (TL) ranging from 41.5 to 98 cm (mean = 56 ± 10 cm). Catch per unit effort (CPUE; number of individuals caught per hour per square meter of net) varied among years, attaining the highest value in 2025 (0.10 individuals h−1 m2), and among months, with increased abundance observed in February and May–July. Smaller individuals (less than 55 cm TL) were mostly found between May and July, suggesting that parturition likely occurs during these months. Of four candidate environmental variables assessed (sea surface temperature, dissolved oxygen, salinity, and chlorophyll a), temperature and oxygen had a significant effect on P. pectoralis abundance, with CPUE increasing with rising temperatures (peaking at 26–27 °C) and with higher oxygen concentrations. Our findings indicate that Sal Rei Bay may serve as a potential nursery area for this endangered shark species, providing key information for national authorities and conservationists to safeguard this critical habitat, namely through its designation as a marine protected area.
The small turbellarian-like gastropod Rhodope is found worldwide, with currently eight recognised species, as well as a few unidentified Rhodope species. Rhodope veranii (Heterobranchia, Mesoneura) is the species first recorded in the Mediterranean Sea. Typical to this family, it lacks distinctive features of heterobranchs, such as a heart, gills, shell, or radula. Molecular analysis has placed it as basal Heterobranchia. Rhodope veranii has been known from the Mediterranean Sea for over two hundred years. Due to its cryptic lifecycle, it has only been described from a few locations across the basin, mainly from the northern parts. As part of the meiofauna, it is reported from shallow waters up to 14-m depth, associated with sand, gravel, and various algae. This simultaneous hermaphrodite ranges in size from 1 to a maximum of 8 mm. This study reports the presence of R. veranii across multiple substrates in a natural bay off the western coast of Libya. In addition to providing a list of nominal Rhodope species, this report represents the first record of the species in both Libyan waters and North Africa.
Biodiversity in the Mediterranean is undergoing rapid restructuring due to climate change and the spread of non- and noteworthy indigenous species (NIS and IS). This study presents the first integrated assessment of alien species distribution along the Turkish Aegean coast, utilizing SCUBA surveys, acoustic seabed mapping, and in situ environmental measurements collected between June and August 2024. Data from 312 diving (5–40 m) and grab samples (40–50 m at 9 stations in total) were analyzed to characterize NIS and IS assemblages and their habitat associations. A total of 17 alien and 2 remarkable native species were recorded, including eight macroalgae, one seagrass (Halophila stipulacea), seven fishes, and four invertebrates. Three macrophytes—Caulerpa cylindracea, Caulerpa taxifolia, and Stypopodium schimperi—were dominant, with C. cylindracea increasing toward the north while others remained confined to southern sectors. Invasive fishes, such as Pterois miles and Torquigener hypselogeneion, showed strong associations with seagrass patches and mixed substrates between 10 and 30 m. Significant regional differences in species composition were observed (PerMANOVA, p < 0.05), driven primarily by distinct water masses. Near-bottom temperature and salinity were the strongest environmental drivers, explaining 23.6
