The West Atlantic trumpetfish Aulostomus maculatus is a species of little commercial importance, but it is frequently used as a study organism in behavioural ecology, and it has been traded in the aquarium industry to some extent. The adult life stage is well described, however its early life history is nearly unknown. This paper provides the first description of post-flexion larvae of A. maculatus, including detailed illustrations, photographs, morphological data, and collection site data of specimens collected during a multipurpose research survey conducted within the Sargasso Sea Subtropical Convergence Zone. The collection site also implies a geographic range expansion, off the continental shelf, of the pelagic larvae stage. This paper hence advances the scientific knowledge about the early life stages, distribution and ecology of this species.

Gecarcinid crabs have their life cycles in antagonistic scenarios, with their larvae developing in the sea and the juvenile/adult phases occurring on land. Adults migrate from land to sea to release their larvae, which return to land upon reaching the megalopa stage. Recruitment and early instar traits in gecarcinids crabs remain unknown, leading to some species lacking age-specific information. Despite massive recruitment observed in some insular gecarcinid species (e.g. Gecarcoidea natalis), recruits are generally expected to be few and exhibit cryptic behaviour, potentially occupying the burrows of conspecifics. We evaluated whether recruits of Johngarthia lagostoma on Trindade Island, Brazil, co-inhabit larger conspecific burrows, analysing this occurrence and examining their growth patterns, density, and body size across different lunar phases. Johngarthia lagostoma recruits inhabit conspecific burrows, either abandoned or occupied by adult crabs, but always with leaves stored in the inner chamber. Recruits in co-inhabiting behaviour reach a maximum carapace width of 7.3 mm, and after that, they are likely detected by the adults and possibly cannibalized or leave burrows naturally. During the full moon, the higher density and smaller size of recruits were recorded, indicating a recruitment lunar phase. It is crucial to ascertain the prevalence of co-inhabitation behaviours in other land crab species to expand the knowledge about recruitment patterns in these key community species.

This study presents the first comprehensive annotated checklist of polychaetes collected from floating dock communities across New England and adjacent New York areas, emphasizing the significance of rapid biodiversity assessment surveys in understanding marine biodiversity. With 61% of the identified species classified as cryptogenic, the research highlights the complexity of marine biogeography and the challenges of distinguishing between native and non-native species. The incorporation of DNA barcoding has significantly improved species identification and revealed the presence of cryptic species complexes. The study's findings illustrate the prevalence of tubicolous families (Spionidae, Serpulidae, Sabellidae, and Terebelllidae) that are susceptible to anthropogenic dispersal mechanisms. It also addresses the challenge posed by the high proportion of cryptogenic species, calling for enhanced taxonomic and genetic analyses to resolve their origins and ecological roles. Despite the temporal variation in polychaete composition across years, the absence of distinct community assemblages suggests a level of resilience within floating dock communities. Our study advocates for the continuation and expansion of rapid assessment surveys, coupled with the integration of genetic methodologies, to provide a clearer picture of marine biodiversity.

Starting in the summer 2023 and peaking in late 2023, large amounts of Sargassum were observed floating off the coast of Madeira Islands, Portugal. The analysis of the samples revealed the presence of the three most common morphotypes of the two known species of pelagic Sargassum: S. natans I, S. natans VIII, and S. fluitans III. This is the first record for the subtropical eastern Atlantic Ocean for S. natans VIII and S. fluitans III. Both species were found entangled, and even though the main purpose of the study was to document the occurrence of pelagic Sargassum in the Madeira archipelago, some associated fauna were also recorded: the crab Planes minutus (Linnaeus, 1758), the amphi-Atlantic shrimps Latreutes fucorum (Fabricius, 1798) and Hippolyte coerulescens (Fabricius, 1775), and the nudibranch Scyllaea pelagica Linnaeus, 1758. The last two are new records for the Madeira archipelago.

Panulirus stimpsoni is restricted to southern China, Vietnam, and Japan but has been rarely reported in tropical Gulf of Thailand. In Malaysia, only six species were previously reported. This study (1) reports the seventh Malaysian species – a new record of P. stimpsoni with morphological and genetic data; (2) establishes a checklist of Malaysian Panulirus species. Surveys from 2021 to 2022 sampled lobsters across Malaysia by SCUBA or from fishermen. Seven species were identified and a modified key of Malaysian species was constructed. The COI gene was used for genetic identification and phylogenetic tree reconstruction with maximum likelihood (ML). The best model was GTR + I + G. The ML tree comprised Clades I and II with sequences clustering by species and strong support. Most Peninsular Malaysian lobsters were P. polyphagus while P. versicolor dominated Sabah. Information on P. stimpsoni's full fishery potential, distribution, ecology, and biology is limited. Further research is needed to ensure conservation and management as data are only available for six previously reported species. Further studies are required to discover sustainable use approaches for all Panulirus species, particularly P. stimpsoni, given limited ecological understanding.

Larval settlement is an important process that drives population and community dynamics of marine invertebrates. Barnacles are frequently used to investigate settlement mechanisms of marine invertebrate larvae. Adult barnacles induce settlement of conspecific larvae nearby which ultimately facilitates copulation with neighbouring individuals. A significant factor involved in the larval induction process is the proteinaceous waterborne settlement pheromone (WSP), which is purified from adult barnacles. A previous study suggested that the concentration of WSP informs barnacle cyprid larvae about the abundance of adult barnacles in the environment nearby but it is unclear whether WSP works in a species-specific or non-species-specific manner. In this study, we conducted settlement assays using recombinant WSPs and cyprids of two congenic barnacle species, Amphibalanus amphitrite and A. improvisus, to investigate the species specificity of WSPs. We found that A. amphitrite and A. improvisus cyprids responded similarly to con-specific WSPs as to allo-specific WSP stimuli indicating that WSPs are not species-specific. Our findings suggest that cyprids approach potential settlement sites using WSPs, non-species-specific settlement pheromones, before performing a closer search of the substratum using a species-specific pheromone.

The genus Maculabatis is a group of batoid rays from the Dasyatidae family, consisting of two main complexes: the gerrardi (spotted species) and the pastinacoides (plain species). This study investigated the diversity within the Maculabatis gerrardi complex, revealing the presence of two distinct geographical lineages, with a potential new species captured off the coast of Mozambique. Molecular analysis showed a significant divergence: COI sequences from Mozambique specimens exhibited over 99% similarity with M. gerrardi from South Africa but more than 2% divergence from those in the Indo-Pacific. Phylogenetic analysis identified two distinct subclades, suggesting at least two hidden lineages within the genus Maculabatis and consequently possible new undescribed species within M. gerrardi complex. These findings emphasize the importance of conducting additional research that integrates both morphological and molecular methods to better understand the group's diversity and evolutionary dynamics, ultimately supporting the development of effective conservation strategies.

A case of hermaphrodism in a wild Pacific bluefin tuna Thunnus orientalis from the Sea of Japan is reported. Morphologically and macroscopically, the gonad seemed to have both ovarian and testicular surfaces. Histological analysis showed that the gonad consisted of only sexually mature testis in all the sections examined, suggesting that the individual was male. Genetic analysis, however, indicated that the tissue samples from this individual had no male-specific genome region, resulting in it being inferred as a female. The observed inconsistency between genetic and histological analysis could help future understanding of the sex development of tunas.

The ocellated shrimp goby, Tomiyamichthys russus was recorded from peninsular India based on a single specimen from Royapuram Fishing Harbour (13°07′24.49′′ N; 80°17′52.20′′E), Chennai, Southeast coast of India. The specimen was identified as the ocellated shrimp goby, T. russus by identification characteristics such as crosswise rows of small orange spots surrounded by minute dull black circles in the post-orbital and pre-dorsal region; posterior area of the gill membrane orange; operculum with pale violet traces. The morphometric characteristics were compared with the previous reports of ocellated shrimp goby. The present finding is the documentation of rare ocellated shrimp goby from the peninsular Indian coast.

The advent of integrative taxonomy in plankton research, employing molecular and morphology-based identification, promotes the discovery of new biodiversity records, especially of larval stages. The slipper lobster family Scyllaridae consists of planktonic phyllosoma larvae, persisting weeks to many months in the water column. High interspecific larval similarities and inconsistent delineation of stages have hindered the identification of scyllarid phyllosomata to the species level using morphological characteristics. Here we report the first record of the pygmy slipper lobster, Biarctus sordidus, in the Red Sea following the finding of its phyllosoma larva, extending its known distribution from the Persian Gulf to Australia and southern China. We identified the phyllosoma collected from the Northern Gulf of Aqaba as B. sordidus using the mitochondrial 16S and 18S rRNA genes, and described its morphology to determine the larval stage. We further discuss the potential factors contributing to the delayed detection of this species.

Recent increases in seawater temperature have been predicted to induce a poleward shift in the distribution of marine organisms. This study reports the first record of the winter appearance of green turtles (Chelonia mydas) in a habitat restricted to summer and autumn in northeast Japan. One individual was observed by a diver at Tomari-hama on the Oshika Peninsula (38°21′ N, 141°31′ E) on 28 December 2023. Another individual was incidentally captured in a fixed net near Tashiro-jima on the Oshika Peninsula (38°17′ N, 141°24′ E) on 18 April 2024 with a straight carapace length of 41.5 cm and body mass of 6.4 kg. Because previous bycatch surveys show that the earliest and latest appearances of green turtles in this area occurred in late June and late November, respectively, the occurrences reported in this study were two months earlier and one month later. The sea surface temperatures at the time of these observations were 15.9 and 16.0°C, respectively, which are 3.5 and 6.6°C higher than those of normal years. The unexpected winter appearance of green turtles implies an expansion of the habitable period for this species in response to climate change, and it, therefore, is emphasizes the need for continued monitoring surveys to collect additional sightings.

Sea anemones represent a highly abundant and diverse group within marine ecosystems, yet biodiversity analyses in Peru remain comparatively scarce. To enhance the inventory of biodiversity and its distribution, a comprehensive review of the available literature on species from Peruvian waters was performed. Only seven well-documented species (i.e. verified records) were found representing 31.8% of the total species reported in Peru (22 spp.) These seven species are Anthothoe chilensis, Phymactis papillosa (formerly reported as P. clematis), Phymanthea pluvia, Oulactis concinnata, Antholoba achates, Anemonia alicemartinae and Oulactis coliumensis. Overall, specimens were identified in 68 localities, the Actiniidae family exhibited the highest diversity with five species (71.4% of the total), whereas Actinostolidae and Sagartiidae each contributed one species (14.3%). The highest number of scientific publications (18) corresponds to the Lima region, with over twice as many studies as other regions, it is followed by Ica (8), Áncash (7), La Libertad (6), Tumbes (5), Piura (4), Arequipa (3), Tacna (2), Moquegua (1) and Lambayeque (1). However, the studied localities are unevenly distributed across regions. Rocky substrata (~55% of records) are the most reported habitat for sea anemones in Peru, including exposed vertical walls and sheltered crevices, caves and areas under rocks. Despite wide spatial distribution, our results indicate several under-researched regions. The growing interest in these benthic invertebrates over recent decades has revealed over 50% of reported biodiversity, yet many doubts about species described long ago remain. Potential biases in existing data require identification along with further analysis of environmental information.

Verrill's modern Mussismilia (the ‘brain corals’) were described in the 19th century, being hitherto considered endemic reef-building species to Brazil. Contrasting with the original diagnoses, highly variable morphological patterns have been observed among the congeners. Interspecific overlapping of major taxonomical characters has resulted in quite inconclusive use of the skeleton macromorphology for the genus. Intending to corroborate the Mussismilia taxonomy, a comparative morphological approach was developed, combining skeleton macro- and micromorphology. A total of 132 colonies was collected between 13°S and 17°S latitude (Mussismilia hispida = 53, Mussismilia harttii = 41, and Mussismilia braziliensis = 38). Qualitative (n = 9) and quantitative characters (n = 7) were selected (the latter was analysed with Kruskal–Wallis and a principal component analysis). A non-parametric test was adopted due to heteroscedasticity and the irregular sampling among populations. As a result, the corallite diameter and number of septa were significantly distinct among the species (α = 0.05). Micromorphology also differs interspecifically, being distribution and size of septal spines diagnostic for the congeners. Intraspecific variation and morphs are approached, ensuring the relevance of the skeleton for the interspecific delimitation and the species identities. Finally, field identification and/or methods based on image analyses from video transects should be adopted with caution. These practices may provide unreliable data, once the information is restricted to the view of the colony top, resulting in biased identification – majorly if the morphotypes of M. harttii and M. hispida share closely spaced corallites.

In the present study, the spatiotemporal distribution and community structure of surface copepods were investigated in Chabahar Bay, Gulf of Oman, through a year-long sampling programme divided into four distinct periods: post-monsoon (POM), northeast monsoon, pre-monsoon (PRM), and southwest monsoon (SWM). Sampling was conducted at five locations using a horizontal plankton net with a 100 μm mesh size, from the midnight to dawn period. Environmental parameters (temperature, salinity, pH, and total dissolved solids) were also recorded, revealing significant differences (P < 0.0005) across seasons and locations. A total of 38 copepod genera, belonging to five orders and 22 families, were identified, accounting for 66% of the total zooplankton population, while the remaining 34% consisted of non-copepod organisms. The highest and lowest mean abundances of copepods were recorded during the PRM and POM periods, respectively. Excluding copepod larvae, Cyclopoida and Calanoida exhibited the highest annual mean abundances, while Monstrilloida had the lowest. Results show the highest annual mean abundance belongs to the genera Oithona with 167,382 ± 11,089 ind. m−3, Temora with 52,250 ± 3691 ind. m−3, Paracalanus with 40,041 ± 2256 ind. m−3, Acartia with 34,822 ± 3876 ind. m−3, Euterpina with 34,313 ± 1542 ind. m−3, and Oncea with 34,033 ± 2951 ind. m−3. However, the lowest value of 794 ± 259 ind. m−3 belonged to the genus Cymbasoma. The highest mean diversity index (H′) was observed in SWM and POM, while the highest mean species richness index (D) was observed in POM and SWM, and the highest mean Pielou's evenness (J′) was observed in SWM and POM.

In the present study species of the genus Byblis Boeck, 1871, found in India are discussed. Previously, two species of the genus Byblis: B. daleyi (Giles, 1890b) and B. lepta (Giles, 1890a) were recorded from India. The taxonomy and world distribution of the two previously reported species is discussed in the study. Additionally, a new species Byblis kachchhensis sp. nov. is also described based on the specimens collected from Gujarat state, India. This new species is differentiated from its closely related species B. calisto Imbach, 1967 by having large eyes placed very close to each other and entire telson.

The amphipod Incisocalliope aestuarius was recently collected since 2015 in the mesohaline part of the Gironde Estuary (SW France) with a van Veen grab and in the lower intertidal part in oyster bed by hand-picking. A look back at past studies showed that this species was present in this estuary since 1976, whereas the original description of this amphipod comes from Watling and Maurer in 1973, from the East coast of America. The validity of the Incisocalliope genus is herein questioned, and it is proposed to transfer species of the genus Inciscalliope to Parapleustes genus.

The current study represents the first records of elusive cardinalfish, Apogon fugax Gon et al., 2020 and twinbar cardinalfish, Apogonichthyoides sialis (Jordan and Thompson, 1914) from the Gujarat coast, northwestern India. During February 2024, regular fishing surveys were conducted to document a bycatch species assemblage. In the course of this study, a total three specimens of A. fugax and a single specimen of A. sialis were procured from Veraval Fishing Harbour, Gujarat, India. Apogon fugax is reported for the first time from Indian waters, while A. sialis is recorded for the first time from northwestern India. Herein, detailed meristic counts, morphometric measurements and the distribution of the species are described.

A new diosaccin species, Paramphiascella aestuarii n. sp., was found in sediment samples from a shallow estuary in north-western Mexico. The morphological distinction between the new species and its congeners is discussed. The new species is morphologically close to P. calcarifer (Sewell, 1940) from the Maldivian Archipelago. However, P. calcarifer differs from the new species in the proximal and subdistal outer spiniform processes on the female second antennulary segment. Bayesian inference based upon molecular characterization (nuclear 18S ribosomal DNA and the mitochondrial cytochrome oxidase subunit I genes) places the new species within a large group of Diosaccinae Sars G.O., 1906, for which molecular sequences are available, composed of Typhlamphiascus typhlops (Sars G.O., 1906), Rhyncholagena cuspis Yeom and Lee, 2023, Robertgurneya jejuensis Yeom and Lee, 2022, and Amphiascoides Nicholls, 1941. The close relationship with Amphiascoides as its sister genus, only morphologically distinct in the structure of the second endopodal segment of the male second swimming leg, is also confirmed.

Oysters have unique life history strategies among molluscs and a long history in the fossil record. The Ostreid form, particularly species from the genus Crassostrea, facilitated the invasion into intertidal, estuarine habitats and reef formation. While there is general acknowledgement that oysters have highly variable growth, few studies have quantified variability in oyster allometry. This project aimed to (1) describe the proportional carbonate contributions from each valve and (2) examine length–weight relationships for shell and tissue across an estuarine gradient. We collected 1122 C. virginica from 48 reefs in eight tributaries and the main stem of the Virginia portion of the Chesapeake Bay. On average, the left valve was responsible for 56% of the total weight of the shell, which was relatively consistent across a size range (24.9–172 mm). Nonlinear mixed-effects models for oyster length–weight relationships suggest oysters exhibit allometric growth (b < 3) and substantial inter-reef variation, where upriver reefs in some tributaries appear to produce less shell and tissue biomass on average for a given size. We posit this variability may be due to differences in local conditions, particularly salinity, turbidity, and reef density. Allometric growth maximizes shell production and surface area for oyster settlement, both of which contribute to maintaining the underlying reef structure. Rapid growth and intraspecific plasticity in shell morphology enabled oysters to invade and establish reefs as estuaries moved in concert with changes in sea level over evolutionary time.

Although nudibranchs are common and attractive animals, our understanding of these marine gastropods in Vietnam remains limited. Prior research has suggested that combining morphological examination with molecular analysis results in more accurate identification of nudibranchs. However, previous studies in Vietnam have typically relied solely on morphological methods for nudibranch identification. In this study, the nudibranch species Halgerda batangas was recorded in Vietnam for the first time based on both morphological and molecular approaches. Halgerda batangas was characterized by a network pattern consisting of orange lines, relatively low dorsal tubercles with red-orange caps and white basal rings, and an orange line along the foot margin. Molecular analysis corroborated the morphological findings. These results suggest that integrating morphological and molecular methods is an effective approach for identifying nudibranchs.