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Amathillopsidae is a widely distributed, but rarely sampled family of deep-sea amphipods. During a recent expedition to the North Atlantic, specimens were filmed clinging to a polychaete tube in situ at abyssal depths by a Remote Operated Vehicle and then sampled for further study. The species was new to science and is described in detail herein. A barcode sequence is provided. Further investigations of photographic and video records revealed the genusAmathillopsisto be more widely distributed, both geographically and bathymetrically, than indicated by current literature records, and that these species occur at abyssal depths in all oceans. Specimens ofAmathillopsisare reported clinging to a variety of different organisms whose erect structures provide the means to raise these charismatic deep-sea predators above the seafloor facilitating feeding opportunities.

Multiple calcareous worm-like boring casts occur on the inner surface of the calcitic external layer of the bivalve Leptodesma sp. from the Kaugatuma Formation (lower Přidoli, Upper Silurian) of Saaremaa Island, Estonia. Most of the boring casts are oriented with their apertures towards the posterior margin of Leptodesma sp. The worm-like casts were originally borings in the aragonitic layer of the valve. The borings were filled with sediment and the aragonitic layer of the bivalve later dissolved. The orientation of the borings indicates that they were likely made during the life of Leptodesma. The boring worms likely used the feeding currents of the bivalve to capture suspended nutrients, so they may have been kleptoparasites. Based on the morphology of borings in Leptodesma, they likely housed some type of filter-feeding polychaete annelid.

The cyclopoid copepod family Bradophilidae includes a few species of mesoparasitic copepods infecting flabelligerid polychaetes. It contains two species of Bradophila Levinsen, 1878, the type genus: B. pygmaea Levinsen, 1878 and B. minuta Boxshall, O'Reilly, Sikorski & Summerfield, 2019, both known from North Europe. Two other genera (i.e., Trophoniphila M'Intosh, 1885 and Flabellicola Gravier, 1918) have some affinities with this family including their host preference. Mesoparasitic copepods are highly specialized, morphologically reduced forms. Part of their body (endosoma) is partially lodged in the host body and the other part is external (ectosoma); both parts are connected by an intersomital stalk. Infection by these copepods can be readily detected by the presence of the egg-carrying ectosoma on the host external surface. From the analysis of flabelligerid polychaetes collected in 2012 from the Chukchi Sea, two ovigerous female individuals of a bradophilid copepod were recorded. These specimens were recognized as representative of an undescribed species of Bradophila. The new species, B. susanae n. sp., shows the generic diagnostic characters and differs from its two other known congeners in several respects, including the cuticular ectosomal ornamentation, body proportions, size of the intersomital stalk, position of the genital pore, and shape and arrangement of egg sacs. Also, the new species ectosomal size range (0.440 - 0.450 μm) falls between the size range of its two known congeners. Our finding expands the known host range of bradophilid copepods to include a new flabelligerid host, Bradabyssa nuda (Annenkova-Chlopina) from the Russsian Arctic region.

In this study we report a new record of a cryptogenic polychaete from southern Africa. The species was found inhabiting sand tubes in intertidal sand flats in the Knysna Estuary on the southern coast of South Africa. Morphological comparisons using light and scanning electron microscopy showed extensive taxonomic similarities with Dipolydora socialis described from other localities and from museum vouchers. In addition, 18S rRNA and COI barcodes were generated for the species. Genetic analysis of the assembled polydorid dataset corroborated the morphological data in delineating the species as a taxonomic unit with >99% genetic similarity to available sequences of D. socialis in the GenBank database. Dipolydora socialis has been reported as having a widespread distribution, and since it can reside within tubes associated with fouling communities or as a shell borer, several vectors may have been responsible for its global spread and introduction to southern Africa. Finally, considering the many cryptic complexes that are currently being uncovered within polychaetes, including spionids, future taxonomic studies should incorporate additional genetic data from other regions of the world to determine whether D. socialis may also be part of a larger species complex.

The present study reports polychaetes that bore into limestone rocks along the east coast of the Aegean Sea (eastern Mediterranean). Rock materials were collected at two depth intervals (0-5 and 5-10 m) at 15 stations in four localities of Ildiri Bay. A total of 276 specimens belonging to 12 species and four families (Eunicidae, Spionidae, Cirratulidae and Sabellidae) were recorded. Specimens belonging to Dodecaceria and Pseudopotamilla were identified at the genus level, because they differ from described species, were few in number or were in poor condition. Dipolydora giardia is a new species to the marine fauna of Turkey. The most dominant and frequent family in the area was Eunicidae, followed by Spionidae. Lysidice ninetta and L. margaritacea comprised 59% of the total number of individuals. The number of species and individuals, and the diversity index did not change with regard to depth or locality. Two species assemblages were found in the area, mainly formed by Dipolydora and Lysidice species. The Lessepsian species, Palola valida, which is a new record for the Aegean Sea, occurred abundantly at the study sites, posing a risk of damage to limestone rocks in the Mediterranean Sea. The morphological features of the species identified at the generic level and the burrow structure of these species are presented. The burrow shapes of Palola siciliensis and P. valida were described for the first time in the present study; they constructed complicated galleries, including more than four entrances., TUBITAK [111Y141], This work was financially supported by TUBITAK (Project number: 111Y141).

The global biogeography of polychaete worms has never been assessed previously. In the present study, we studied the world distribution patterns of polychaetes based on datasets obtained from the Global Biodiversity Information Facility, the Ocean Biogeographic Information System and our recently published checklist of Indonesian polychaete species. Polychaete biogeographic regions were visualized using ‘Infomap Bioregions’, and the latitudinal species richness gradient of the animals was examined using 3 metrics, i.e. alpha, gamma and estimated species richness (the last metric was adjusted for sampling bias). We identified 11 major polychaete biogeographic regions. The North Atlantic, Australia and Indonesia were the top 3 species-rich biogeographic regions in the world. The total number of polychaete species was higher in the southern hemisphere (~2100 species, 67 families) than in the northern hemisphere (~1800 species, 75 families) despite significantly more data in the latter (>500000 records compared to >26000 records). Contrary to the classical idea of a unimodal distribution pattern, the latitudinal gradient of polychaetes was generally bimodal with a pronounced dip north of the Equator (15°N). We suggest that the slightly higher peak of species richness in the southern (30°S) than in the northern (60°N) hemisphere reflects higher southern endemicities. These patterns are unlikely to be due to sampling bias but rather represent a natural phenomenon, and we found them most significantly correlated with sea temperature.

The present study investigated the structure of the crab Clibanarius symmetricus (Randall, 1840) population found in a biogenic reef formed by the polychaete Sabellaria wilsoni Lana & Gruet, 1989 o...

Camacolaimidae is a clade of nematodes that include both free-living epistrate feeding forms and parasites of marine protozoans and invertebrates. Neocamacolaimus parasiticus is a parasite of marine polychaete worms. Given its phylogenetic affinities to free-living species, Neocamacolaimus can be a reference for research of the origin of parasitism in an aquatic environment. Here, we present a draft transcriptome obtained from a single post-parasitic juvenile individual of this species. The final assembly consists of 19,180 protein coding sequences (including isoforms) with the following BUSCO scores for Nematoda: 65.38% complete, 9.06% partial, and 25.56% missing, and for Metazoa: 79.45% complete, 3.17% partial, and 17.38% missing.

The present study investigates the influence of seasonal dynamics on macrobenthic assemblages in four seasons of 2017–2018 from the central sector of Indian Sundarbans which is under the constant threat of climate change. Besides taxonomic analysis, a trait-based approach has also been applied to assess the change in their ecosystem functioning. The maximum species density (11675 ± 11883.31 ind. m−2) was observed during the spring season which declines considerably in the monsoon season (5875 ± 6224.08 ind. m−2). A total of 95 macrobenthic taxa were recorded from Sundarbans and they were dominated by families like Capitellidae, Donacidae, Magelonidae, Nereididae, Paraonidae and Spionidae. Overall, polychaetes have shown higher taxonomic and functional variation than other groups. Opportunistic polychaete species have shown a prominent compositional shift during post-monsoon seasons. Both the univariate and multivariate analyses have shown a significant relation between macrobenthic composition and environmental parameters. SIMPER has depicted that environmental parameters made the station 4 unique for several types of molluscs like Acteocina estriata, Stenothyra deltae and Meretrix meretrix during spring. Trait percentages also showed a seasonal succession pattern and among the trait categories, burrowers and deposit feeders dominated the estuary. A gradual increase in suspension feeders in spring has been noticed. RLQ approach with fourth-corner analysis was used to unravel the relationship between traits and environmental parameters. Hence, the present study provided a comprehensive idea about the species composition along with their trait categories from such a dynamic habitat. That could be the first stepping stone for a long term monitoring of macrobenthic assemblages from this largest delta on earth.

Studies of holoplanktonic polychaetes in the Tropical Eastern Pacific have focused on their systematics and distribution however, population responses related to climate variability are non-existent. Therefore, the present work described for the first time the influence of the climatic variability 2004-2012 on the holoplanktonic polychaetes populations, as well as their relationship to environmental variables. Species of the Alciopidae, Lopadorrhynchidae and Iospilidae families were identified from 85 samples collected in the Pacific Basin of Colombia, contrasting them with the presence of ENSO, and correlating them with the environmental variables of temperature, salinity and chlorophyll-α concentration. Of the 14 species identified, only Lopadorrhynchus cf. henseni and L. cf. brevis increased their densities under El Ni?o and correlated positively with temperature. Rhynchonereella cf. petersii correlated negatively with temperature; while R. cf. gracilis and Pelagobia cf. longicirrata were positively correlated with chlorophyll-α concentration and salinity, respectively. Additionally, with the first description of the environmental ranges of the 14 species identified for the Colombian Pacific basin, it was found that the most commons species presented broader environmental ranges. The results from the current research are consistent with previous studies in other regions of the Pacific and latitudes. The responses of the organisms suggest trophic and mobility trends that were not known for tropical holoplanktonic polychaete species.

A new spionid polychaete was discovered in deep-sea sediments in the eastern Mediterranean Sea during an expedition by the Ocean Exploration Trust. Specimens were collected by the E/V Nautilus in August 2012 off Turkey, at a depth of 2216 m on the Anaximander Seamount at the Amsterdam mud volcano site. Cores were taken from sediments covered with microbial mats. The new species belongs to the Pygospiopsis-Atherospio Group, which has unusual neuropodial hooks, modified neurosetae in some anterior setigers, and branchiae in middle body segments that are broad, flattened, and fused to the dorsal lamellae. The new species is assigned to a new genus and species, Aciculaspio anaximanderi n. gen., n. sp., and is unusual in having a reduced setiger 1 lacking notosetae; well-developed pre- and postsetal lamellae that encompass the neurosetae and notosetae; notopodial lamellae free from the branchiae in anterior setigers that become fused and flattened in middle and posterior segments; unidentate hooded hooks in both noto- and neuropodia; neuropodial spines in setigers 4–10; and a pygidium with three anal cirri. Aciculaspio anaximanderi n. gen., n. sp. is the first species in the Atherospio-Pygospiopsis Group collected from a deep-water cold seep habitat.

A new spionid species Polydora lingulicola sp. nov., a novel symbiont of Lingula anatina Lamarck, 1801 is described here based on materials collected from the Yatsushiro Sea and Ariake Sea, southern Japan. Polydora lingulicola sp. nov., morphologically closest to P. glycymerica Radashevsky, 1993 and P. vulgaris Mohammad, 1972, is distinct from latter two shell-boring species by its smaller size, long maximum caruncle length, non-boring lifestyle, presence of subspherical yellow chromatophores on chaetiger 5 (visible in living specimens), and larval morphology. The new species was observed to construct mud tubes on the surfaces of L. anatina shells, with the tube apertures located near the lateral inhalant pseudosiphon of the hosts, and utilizes the water currents created by the filter-feeding host for feeding suspended food particles. Polydora lingulicola sp. nov. represents the first polychaetous annelid reported to exhibit an obligate symbiotic relationship with a lingulid brachiopod. Epibiotic polychaetes previously reported as P. cornuta Bosc, 1802 to occur on L. anatina shells from Japan in 1902 may belong to P. lingulicola sp. nov. The possibility that the wild populations of P. lingulicola sp. nov. may be vulnerable to extinction because they only associate with L. anatina, wild populations of which are near threatened by habitat loss, coastal pollution, and fishing pressure.

The aim of this study was to describe and analyze the structure, distribution, and temporal variation in the composition of benthic polychaeta and their relation to abiotic characteristics in marine sediments along the continental shelf of Bahia de Todos Santos, Baja California, Mexico. Benthic macrofauna and environmental variables were collected to coordinated with a long-term ocean monitoring project known as the Southern California Bight Regional Monitoring Program. A total of nineteen stations were collected in September 1998, twenty stations in November 2003, fifteen stations in December 2013 and sixteen stations in September 2018. These data were compared to assess the response of benthic polychaete assemblages to natural and human induced changes in sediment characteristics. All stations were sampled using a Van Veen grab (0.1 m2) at depths between 15 to 206 m. Sites were selected using a multiple density nested random-tessellation stratified design. Environmental parameters measured included depth (m), sediment grain size

Small specimens of a seemingly undescribed nereidid polychaete species from Tampa Bay, Florida, USA lacked notopodial falcigers, paragnaths and papillae on the pharynx, and dorsal ligules. Quantitative analysis of a larger size range of material showed that all specimens could be referred to Nereis (Neanthes) micromma Harper, 1979. The use of Neanthes Kinberg, 1865 as a subgenus of Nereis Linnaeus, 1758 is no longer accepted and this species is now formally referred to Neanthes micromma Harper, 1979, which is here redescribed to better account for the observed size-related variation. Contrary to the original description, in this species, notaciculae are present in chaetigers 1 and 2, but difficult to observe. Given that earlier studies have identified the potential phylogenetic significance of presence of notaciculae, it is suggested that re-evaluation of this character in similar Nereididae may assist in revising the status of the polyphyletic genus Neanthes.

Nocturnally swarming polychaetes were sampled over a ten-year period (2007–2017) in shallow waters of the Virgin Islands National Park, St. John, United States Virgin Islands. While sampling was qualitative and conducted over different years, months and lunar phases, some patterns were noted in the emergence of swarming polychaetes. Three families (Nereididae, Opheliidae, and Syllidae) had members that swarmed on most nights, while reproductive epitokes from two families appeared only during specific lunar phases: Goniadidae around the full moon and Phyllodocidae around the new moon. Additional polychaete families represented included Amphinomidae, Dorvilleidae, and Scalibregmatidae, whose members swarmed during the waning or waxing lunar phases. This overview offers new information about the timing of reproductive swarming in Caribbean polychaetes and suggests some connections between lunar phases and the swarming of different families.

Community structure and seasonal changes in the population structure of pelagic polychaetes were studied based on zooplankton samples collected by sediment traps moored at 200 m depth in the subarctic and subtropical western North Pacific throughout the year. Eight species belonging to seven genera and seven families occurred at the subarctic station, while twelve species belonging to ten genera and seven families were identified at the subtropical station. Polychaete abundance was 5.37 ± 0.44 ind. m-2 day-1 (annual mean ± standard error) at the subarctic station, and 1.36 ± 0.15 ind. m-2 day-1 at the subtropical station. Polychaete abundance at the subarctic station was high from May to August, but no seasonal patterns were observed at the subtropical station. The dominant species in the subarctic was Tomopteris septentrionalis, which accounted for 62.9% of annual mean abundance; at the subtropical station, the dominant species was Pelagobia sp. (22.8%). In the subarctic, small specimens of T. septentrionalis (

Functional redundancy assumes a critical relevance nowadays due to the serious threats that affect marine life worldwide. We assessed and compared levels of functional redundancy in polychaete assemblages from the continental shelf and from estuarine environments along the South Brazil Shelf Large Marine Ecosystem (SBSLME). To quantify functional redundancy, we used functional originality (FOri) and functional uniqueness (FUni). We found 57 and 47 polychaete taxa distributed in 48 and 41 functional entities (i.e., a unique combination of trait values) in continental shelf and estuarine environments, respectively. Results suggest a low level of functional redundancy in both environments. However, FOri was higher in the estuarine environment, whereas FUni was higher in the continental shelf. As expected, estuarine polychaetes have fewer unique combinations of trait values, but these combinations are more original and adequate to the varying conditions imposed by estuarine environmental drivers.

An update of the geographical distribution of the sabellariid polychaete Sabellaria alveolata (Linnaeus, 1767) within the Mediterranean Sea is provided after checking the known literature. This shallow-water, reef-forming species is first recorded from new sites in southeastern Sicily, both along the Sicily Straits and the Ionian Sea, from where S. alveolata was so far unknown.These new collections also provided material for a detailed description and SEM documentation of morphological features of the operculum and the body.

Although parasitism is one of the most prevalent interactions in nature, studies of aquatic food webs rarely include parasites. Syndiniales (Dinophyceae, Alveolata) is a diverse parasitic group of dinoflagellates, common in all marine environments, and are described as dominant components of pelagic ecosystems. However, their temporal dynamics, prevalence, and host-specificity are poorly known. Using DNA metabarcoding to explore trophic interactions of zooplankton, we found a high proportion of Syndiniales sequence reads associated with the targeted consumers. We observed the occurrence of Syndiniales in copepods, cladocerans, appendicularians, and polychaete larvae, ranging between 11 and 36% relative read abundance, encompassing 11 main putative clades. Zooplankton–Syndiniales interactions showed variability in occurrence across the taxa, but also certain host-specificity. The study suggests that the observed copepod–Syndiniales interactions can be both direct parasitic infections and the result of trophic transmission through potentially infected prey by Syndiniales. Given the quantitative importance of Syndiniales and zooplankton in marine environments, our findings emphasize that their interactions should be recognized as key players in the structure and connectivity of plankton food webs.

The Canary Islands are the richest volcanic region in the world in subterranean adapted fauna, followed by the Hawaiian Islands and the Undara Cave in Australia. Most of the subterranean adapted aquatic fauna from the Canary Islands is restricted to the anchialine environments in La Corona lava tube in Lanzarote, while the oligohaline stygobiont fauna, usually found in groundwater or interstitial freshwaters, is scarcer and represented by a few species of amphipods, copepods, and a single polychaete annelid recorded from Fuerteventura and doubtfully identified as Namanereis hummelincki (non Augener, 1933) (Hartmann-Schröder, 1988). Two new species of polychaete annelids belonging to the subfamily Namanereidinae are described from Gran Canaria and Fuerteventura. Both species live in groundwater, are depigmented and eyeless, and have bifid jaws. Although they are seemingly more related to each other than to other members of the bifid-jaw group, Namanereis canariarumsp. nov. can be diagnosed by its relatively longer tentacular cirri and parapodial dorsal cirri, as well as the presence of pseudospiniger chaetae. In contrast, Namanereis llanetensissp. nov. has shorter cirri and usually lacks pseudospiniger chaetae. Namanereis canariarumsp. nov. and Namanereis llanetensissp. nov. increase to 20 the total number of currently described species within this enigmatic genus. More than half of those species are adapted to live in groundwaters.

Zooplankton aggregation, hydrographic and remote sensing data were employed to relate the spatial dynamics of neustonic communities with chlorophyll a (Chl a) and suspended organic matter (SOM) at a spatial mesoscale (10 to 1000 km) in the southern Chilean fjords system along Magellan Strait, Chile (CIMAR 16: October/November 2010 and CIMAR 25; September/October 2019) in order to identify oceanographic process producing aggregation of neuston. Preliminary evidence of CIMAR 25 shows significant concentrations of Chl a and SOM around Dawson Island (DI), Magellan Strait. During CIMAR 16 important aggregation of specific neustonic taxa (copepodites of Microsetella rosea, larvae of the polychaete Polygordius sp and cyphonautes of the bryozoan Membranipora isabelleana) was observed around DI, Magellan Strait. Satelital images in the area of CIMAR 16 provide evidence of important aggregation of chlorophyll a/SOM around DI. CIMAR Cimar 25 showed that the Chl a and SOM aggregation around DI is recurrent and could to explain the high concentration of neuston around this island to spite of mesotrophic conditions. Remote sensing in this study area provides a tool to understanding oceanographic and topographic factors that potentially regulate the abundance and spatial distribution of surface zooplankton to spatial meso-scale along Magellan Strait.

Invasions of marine species are changing coastal food webs worldwide, impacting on trophic interactions between native species (e.g. predator-prey relationships). Here, the impact of 3 macrozoobenthic invasive species on food web structure and functioning at Balgzand (western Wadden Sea) is quantified by using ecological network analysis (ENA). The bivalves Ensis leei and Magallana gigas were observed for the first time in 1984 and 2001, respectively, and the polychaete Marenzelleria viridis appeared in 1989. Although E. leei and M. viridis reached similar peak biomasses in the 2000s (ca. 1700 and 2000 mg C m-2, respectively), the bivalve consumption was higher (>45% of total consumption) than that of the polychaete (M. gigas remained relatively low. E. leei occupied an ecological niche that was relatively unoccupied, which led to competitive advantage with respect to other suspension feeders. Increasing biomass of E. leei coincided with a 70% increase of trophic carbon transfer from primary to secondary producers and an 80% increase from secondary producers to detritus. Carbon flows from secondary producers to higher trophic levels were reduced by more than 60%. These shifts in trophic transfer were stronger than those observed during the invasion of M. gigas in the NE Wadden Sea. At Balgzand, biomass of M. gigas and M. viridis rapidly declined to low values in the 2010s, implying a temporally limited impact. In the 2010s, E. leei was still responsible for 30% of the total consumption in the 2010s, indicating a longer-term impact.

Capitellid polychaetes are ubiquitous throughout the world’s oceans and are often encountered in high abundance. We used an extensive dataset of species abundance and distribution records of the Capitella capitata complex, C. aciculata, C. jonesi, Heteromastus filiformis, Mediomastus ambiseta, and M. californiensis from Tampa Bay, Florida, USA, as a model system of closely related species filling a similar ecological niche. We sought to (1) characterize the spatial distribution of each species, (2) determine if a single species abundance modeling strategy could be applied to them all, and (3) assess environmental drivers of species distribution and abundance. We found that all species had a zero-inflated abundance distribution and there was spatial autocorrelation by bay regions. Lorenz curves were an effective tool to assess spatial patterns of species abundance across large areas. Bay segment, depth, and dissolved oxygen were the most important environmental drivers. Modeling was accomplished by comparing 6 different approaches: 4 generalized additive models (GAMs: Poisson, negative binomial, Tweedie, and zero-inflated Poisson distributions), hurdle models, and boosted regression trees. There was no single model with top performance for every species. However, GAM-Tweedie and hurdle models performed well overall and may be useful for studies of other benthic marine invertebrates.

In 2017, Polydora websteri, a shell‐boring spionid polychaete worm and cosmopolitan invader, was identified for the first time in Washington State. Shell‐boring Polydora spp. and related shell‐boring spionid polychaetes (e.g., Dipolydora spp., Boccardia spp.), colloquially known as mud worms or mud blister worms, live in burrows within the shells of calcareous marine invertebrates, reducing the host's shell integrity, growth, survivorship and market value. Mud worms have a long history of impacting shellfish aquaculture industries worldwide by devaluing products destined for the half‐shell market and requiring burdensome treatments and interventions to manage against infestation. Here, we explore the risks of mud worms to the historically unaffected aquaculture industry in Washington State. This mini‐review is intended to inform shellfish stakeholders by synthesizing the information needed for immediate action in Washington State. We review the recent documentation of Polydora spp. in Washington State, discuss their history as pest species globally, summarize mud worm life history, and discuss effective control strategies developed in other infested regions. Finally, we review existing regulations that could be leveraged by stakeholders to avoid introduction of mud worms into uninfested areas of Washington State.

Halla okudai Imajima, 1967 is an oenonid annelid species that inhabits the intertidal and shallow subtidal zones in China, Malaysia, Australia and Japan. This species is harvested and used as fishing bait in Japan and Malaysia; however, it has been regarded as Near Threatened in Japan based on the categories of the Japanese Red List. Here, we reconstructed the molecular phylogeny of Oenonidae based on 16S rRNA gene sequences. This study provides a new record of H. okudai on Fukue Island, in the Goto Islands, Japan.