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One new species of Caulleryaspis Sendall & Salazar-Vallejo, 2013 (Annelida: Sternaspidae), C. chicosciencei sp. nov., is described based on material collected in north-eastern Brazil. Specimens were collected in muddy bottoms in the Suape estuary complex in 7–16 m water depth. Caulleryaspis chicosciencei sp. nov. differs from the other known species by the combination of the following characters: small size, abundant cirriform papillae evenly distributed throughout body; chaetigers of introvert with 18–21 falcate hooks per bundle; ventral shield without ribs and undeveloped concentric lines, covered by long cirriform papillae with sediment particles adhered; marginal chaetal fascicles include eight lateral shield chaetae in an oval arrangement, and six posterior shield chaetae in slightly curved pattern. Caulleryaspis chicosciencei sp. nov. is the first species of the genus Caulleryaspis described from Brazil and it increases the number of sternaspids recorded from shallow water in the south-western Atlantic Ocean. [ABSTRACT FROM AUTHOR]

The complete mitochondrial genomes of Notomastus sp. (15,776 bp) (Annelida: Capitellidae) and Armandia sp. (18,538 bp) (Annelida: Opheliidae) were assembled for the first time. A group II intron (303 bp) was found in cox1 of Notomastus sp. A phylogenetic analysis revealed that Notomastus sp. and Armandia sp. were monophyletic, and this clade was clustered with echiurans, although the possibility of the effect of long-branch attraction should be considered.

Mass spawning dates of nyale worms (Eunicidae) have been scientifically predictable since 2019. The month of spawning is consistently following the pattern of the February full moon, while the date of spawning is consistently on the 20th of the lunar calendar. There are particular years with February only spawning, March only spawning, and split spawning in both February and March. The existing prediction of the split spawning, however, was constructed with very little available data. The present study aimed to revisit the split spawning prediction using the Metonic cycle, a 19-year lunisolar cycle. The results show that the spawning prediction very much follows the Metonic Cycle. There are minor dates on split spawning to be revised, when February full moon rises on 14th February. The revised hypothesis is that split spawning is very likely to occur when the full moon rises between the 7th to 13th of February. When February full moon appears before the 7th of February, single spawning will take place on the fifth day after the March full moon. When February full moon befalls after the 13th of February, single spawning will occur on the fifth day after the February full moon. The revised prediction method has only 2 (two) deviances in 114 years of simulation dates. The present study is the first to suggest the link between Polychaete spawning patterns and the Metonic Cycle.

The genus Dendronereis Peters, 1854 is characterized in the polychaete family Nereididae by its feather-shaped branchiae on the anterior segments. In this study, we present the first complete mitogenome of Dendronereis, represented by D. chipolini Hsueh, , collected from Beibu Gulf, China. The nucleotide composition is biased toward A + T nucleotides, accounting 31.5% for A, 22.3% for C, 14.7% for G and 31.5% for T. The assembled mitogenome is 15,763 bp in length, with a typical set of 13 protein-coding genes (PCGs), 22 transfer RNA (tRNA), 2 ribosomal RNA (rRNA), and 1 non-coding control region. All genes are encoded on H-strand. The control region is 1260 bp in length and located between tRNA-Gly and tRNA-Met. Phylogenetic study showed that D. chipolini is arranged with high support into the clade of Namanereidinae. The complete mitogenome provides important molecular data for investigating the phylogeny and evolution of the nereid animals.

The marine feather duster, Bispira melanostigma (Schmarda, ), is a tube-dwelling annelid that contributes to ecological and biogeochemical processes in benthic communities. Due to the lack of scientific data, B. melanostigma is often difficult to distinguish from other species of marine worms through morphological characteristics alone. In this study, we report the complete mitochondrial genome of Bispira melanostigma. The complete mitogenome contained 20,624 bp length with a total of 13 protein-encoding genes, 21 tRNA, and 2 rRNA genes. Phylogenetic analysis of the complete mitochondrial DNA of B.melanostigma can aid in the understanding of evolutionary relationships within Sabellidae.

Sirsoe methanicola, commonly known as the methane ice worm, is the only macrofaunal species known to inhabit the Gulf of Mexico methane hydrates. Little is known about this elusive marine polychaete that can colonize rich carbon and energy reserves. Metagenomic analysis of gut contents and worm fragments predicted diverse metabolic capabilities with the ability to utilize a range of nitrogen, sulfur, and organic carbon compounds through microbial taxa affiliated with Campylobacterales, Desulfobacterales, Enterobacterales, SAR324, Alphaproteobacteria, and Mycoplasmatales. Entomoplasmatales and Chitinivibrionales were additionally identified from extracted full-length 16S rRNA sequences, and read analysis identified 196 bacterial families. Overall, the microbial community appeared dominated by uncultured Sulfurospirillum, a taxon previously considered free-living rather than host-associated. Metagenomeassembled genomes (MAGs) classified as uncultured Sulfurospirillum predicted thiosulfate disproportionation and the reduction of tetrathionate, sulfate, sulfide/polysulfide, and nitrate. Microbial amino acid and vitamin B12 biosynthesis genes were identified in multiple MAGs, suggesting nutritional value to the host. Reads assigned to aerobic or anaerobic methanotrophic taxa were rare. [ABSTRACT FROM AUTHOR]

Polychaete worms can biotransform polycyclic aromatic hydrocarbons (PAHs) in environments, and the cytochrome P450 (CYP) enzyme plays an important role in this process. Herein, a novel cytochrome P450 gene was identified and characterized from the polychaete worm Perinereis aibuhitensis. The full-length cDNA, which is named CYP4V82, is 1709 bp encoding a protein of 509 amino acids and has high similarity to CYP4V. The expression levels of CYP4V82 and CYP4BB4 (a CYP gene identified from P. aibuhitensis in a previous study, Chen et al. Mar Pollut Bull 64:1782–1788, 2012) exposure to various concentrations of benzo[a]pyrene (B[a]P) (0.5, 2, 4, and 8 μg/L) and same mass concentrations of fluoranthene (Flu, 3.2 μg/L), phenanthrene (Phe, 2.9 μg/L), B[a]P (4.0 μg/L) were detected to identify the function of the CYP4 family in P. aibuhitensis. Compared with CYP4BB4, CYP4V82 mRNA was minimally expressed on day 7 but highly sensitive on day 14. Notably, the expression levels of CYP4V82 and CYP4BB4 were relatively different in short-term responses to PAHs with different benzene rings of the same concentration. The expression of CYP4V82 in the B[a]P group was the highest, while that of CYP4BB4 in the Phe group was relatively higher than the two other groups. These findings suggest that PAHs are associated with the induction of CYP4V82 and CYP4BB4 expressions in P. aibuhitensis, which may have different efficiencies in the detoxification of PAHs. [ABSTRACT FROM AUTHOR]

Reproduction of the terebellid Eupolymnia nesidensis was investigated in a population from the Ionian Sea (Mediterranean, South Italy). This species has a worldwide distribution and is very common on Mediterranean hard substrata covered by algae. Observations revealed a spawning period across springtime with lecithotrophic development occurring inside a jelly mass, with eggs measuring 210 μm in diameter. Juveniles leave the jelly mass after 12–13 days building a transitory tube and exhibiting a vagile benthic behaviour, incorporating food directly through the mouth opening. During the juvenile stage, at day ~100, an ontogenetic shift related to feeding behaviour was observed. Specifically, the vagile feeding behaviour was replaced by the adult feeding strategy with the use of the fully developed head tentacles. [ABSTRACT FROM AUTHOR]

Recent invasions of the North and Baltic Seas by three Marenzelleria species have extensively altered benthic communities in the region. Despite several studies on the morphology and biology of the worms, their morphological identifications are often challenging. Here we summarize and map the available records of Marenzelleria from Eurasia, distinguishing those based on morphology versus molecular data. Based upon the genetic similarity (p = 0.08% for COI) between individuals from the Baltic Sea and individuals from the Barents and White Seas we propose, for the first time, a possible route for the invasion of the Baltic Sea by M. arctia from the White Sea through the White Sea-Baltic Sea Canal. At the same time, our analysis of the sequences of COI fragments showed a significant genetic distance (p = 4.28-4.29%) between individuals identified as M. arctia from the Baltic, Barents and White Seas and those from the Kara Sea. This genetic distance, as well as the isolated estuarine habitats of these Arctic worms, and the large geographic distance between the type locality of M. arctia in the Beaufort Sea (Alaska) and northern Europe, raise doubts about the conspecificity of North American, North European and Northwest Pacific populations. We report M. neglecta for the first time for the British Isles (River Thames). We also review the evidence for the role of the Baltic Sea-Volga Canal and the Volga-Don Canal in facilitating the dispersal of M. neglecta to the Caspian Sea and the Sea of Azov, respectively. We further provide new insight on the phylogeny of Marenzelleria, an updated diagnosis of the genus and a key for morphological identification of Marenzelleria adults greater than 1.2 mm wide. [ABSTRACT FROM AUTHOR]

To date, the genus Amphiduros (Annelida: Hesionidae: Amphidurine) is considered as monotypic. Its single species, Amphiduros fuscescens (Marenzeller, 1875), is well characterised by lacking proboscideal papillae and emerging acicular chaetae, as well as by having three antennae, eight pairs of tentacular cirri and inflated dorsal cirri with characteristic alternating length and color (transparent, with median orange band and white tips) in live animals.Three specimens, one male and two female, were found below boulders at 5–7 m depth in Punta Santa Anna, Blanes, and Cala Maset, Sant Feliu de Guixols (Catalan Sea, NW Mediterranean, Iberian Peninsula). Our finding allowed us to describe different, unreported morphological traits, and lead us to support the existence of sexual dimorphism (in terms of colouring, cirri morphology and distribution of sexual products along the body). Despite the A. fuscescens has been previously reported from the Atlantic and the Mediterranean (particularly in SE French coasts), the specimens from Blanes represent the first record of the species from the Iberian Peninsula. In addition, our molecular results strongly support that Amphiduros pacificus Hartman, 1961 from California (currently synonymised with A. fuscescens) requires to be redescribed and reinstalled as a valid species. In turn, our morphological observations support suggesting all other non-Mediterranean reports of A. fuscescens, including the species still under synonymy (i.e., Amphidrornus izukai Hessle, 1925, Amphidromus setosus Hessle, 1925) as likely being a cryptic complex whose the taxonomic status require further assessment.

Here, we report the complete mitogenome information of the terebellid polychaete, Thelepus plagiostoma (Schmarda, 1861). Genome sequencing by Illumina HiSeq platform permitted assembly of a circular mitochondrial genome of 15,628 bp from T. plagiostoma consisting of 67% AT nucleotides, 13 protein-coding genes (PCGs), 2 ribosomal RNA (rRNA) genes, 22 transfer RNA (tRNA) genes, and a non-coding region in the typical annelid gene composition. Gene order of the T. plagiostoma mitochondrion is identical to those of the Terebelliformia mitogenomes. Phylogenetic reconstruction places T. plagiostoma within the monophyletic subclass Sedentaria, a sister to Pista cristata in the suborder Terebelliformia.

In this study, we report the complete mitogenome sequence of the polychaete, Melinna cristata (Sars, 1851). The circular M. cristata mitochondrial genome is 15,696 bp in length and has an AT content of 66%. As in other polychaetes, the genome has 13 protein-coding genes (PCGs), two ribosomal RNA (rRNA) genes, 22 transfer RNA (tRNA) genes, and a non-coding region. Gene composition and their order in the M. cristata mitochondrion are identical to the Terebelliformia mitogenomes. A maximum-likelihood gene tree based on the M. cristata mitogenome combined with previously published Sedentaria and Errantia mitogenomes revealed that M. cristata forms a clade with two Terebelliformia species.

Neanthes Kinberg, 1865 is a speciose nereidid genus with some species exhibiting epitoky during the timing of reproduction. The epitokal morphology of males and females has long been agreed to be diagnostic to distinguish species. In the present study, we provide redescriptions of the type material and reassess the current taxonomic status of four Neanthes species originally described based on the reproductive forms of specimens collected from Southeast Asia: Neanthes augeneri (Gravier & Dantan, 1934), N. gisserana (Horst, 1924), N. trifasciata (Grube, 1878) and N. trifasciata vandersandei (Horst, 1924). The non-metamorphosed and epitokous diagnostic features, including new characters found in this study, were used to redescribe and distinguish these species from other congeners. The four species are here recognised in Neanthes, whereby N. vandersandei is elevated to species level. Neanthes gisserana is considered as distinct from its previous senior synonym N. rubicunda (Ehlers, 1868). Morphology of both N. trifasciata and N. vandersandei, originally described based on mixed species, is restricted. Additionally, some remarks on the status of N. thysanota (Ehlers, 1908) are given. Distributional and reproductive data of the reviewed species are provided. An updated checklist of 80 valid species in Neanthes and synoptic tables of diagnostic features including the atokous and epitokous morphology are also presented.

Chitin, one of the most abundant biopolymers in nature, is a crucial material that provides sufficient rigidity to the exoskeleton. In addition, chitin is a valuable substance in both the medical and industrial fields. The synthesis of chitin is catalyzed by chitin synthase (CHS) enzymes. Although the chitin synthesis pathway is highly conserved from fungi to invertebrates, CHSs have mostly only been investigated in insects and crustaceans. Especially, little is known about annelids from hydrothermal vents. To understand chitin synthesis from the evolutionary view in a deep-sea environment, we first generated the whole-genome sequencing of the parasitic polychaete Branchipolynoe onnuriensis. We identified seven putative CHS genes (BonCHS1-BonCHS7) by domain searches and phylogenetic analyses. This study showed that most crustaceans have only a single copy or two gene copies, whereas at least two independent gene duplication events occur in B. onnuriensis. This is the first study of CHS obtained from a parasitic species inhabiting a hydrothermal vent and will provide insight into various organisms' adaptation to the deep-sea hosts. [ABSTRACT FROM AUTHOR]

The unusual holopelagic annelid Poeobius meseres Heath, 1930 (Flabelligeridae) was first collected from Monterey Bay, California, and has been subsequently recorded across the northern Pacific from Japan to the Gulf of California. Rare occurrences in the eastern tropical Pacific have extended as far as 7° S off Peru.Using molecular phylogenetic analysis of a newly collected specimen from the Salas y Gómez Ridge off Chile, we extend the known geographic range of P. meseres southward by 2040 km. This subtropical specimen showed higher genetic similarity to a specimen from the type locality (

The reworking of a trace by a subsequently following organism represents a so-called sequorichnial behavior and leads to formation of a “burrowing highway”. Burrowing highways occur more frequently than assumed in the fossil record. Their ichnological and sedimentological meaning is elucidated by using the trace fossil Gyrochorte. Gyrochorte producers exploiting sandy event beds tend to use “burrowing highways” in the same direction. Evidently, the Gyrochorte producers are thigmotactically highly sensitive as they can recognize a burrow produced by the same species because of the less densely packed grains, a somewhat increased mud content, and supposedly mucus segregated within the burrow. These changes make the reworking of pre-existing burrows energetically advantageous. However, in shallow-marine settings mucus is degraded rapidly and loose sediment consolidates in a short while. Therefore, the time to recognize a pre-existing burrow appears to be limited and a rather high number of organisms is a prerequisite for reutilization of a previous trace. “Burrow highways” potentially represent an additional criterion to characterize an opportunistic population strategy.

Symbiotic marine invertebrates can be small, hidden or difficult to find, hampering the understanding of their distribution and ecological roles. Haplosyllis anthogorgicola is a polychaete inhabiting the gorgonian Anthogorgia bocki , where it lives in high densities within the host's coenenchyme and occupies burrows formed by host tissue near coral polyps. This study provides the first records of H. anthogorgicola since its description in 1956, from colonies of Anthogorgiidae in southern Japan. We observed that host gorgonians were also inhabited by the pygmy seahorse Hippocampus bargibanti , a popular species to observe and photograph among SCUBA divers. Therefore, we examined photographic records of H. bargibanti available on the citizen science website iNaturalist and screened for structures associated with infestation by H. anthogorgicola to gather information on this elusive species. Our analyses confirmed that this polychaete and/or similar species are widespread in the central Indo-Pacific region. In addition, we observed some polychaete behaviours, raising questions about the nature of the relationships between H. anthogorgicola , its gorgonian hosts and the pygmy seahorse. Our study demonstrates that citizen science can contribute to our knowledge not only on the distribution and behaviour of well known and charismatic species but also inadvertently on overlooked and neglected taxa.

Here, we report the complete mitochondrial genome of sabellid Pseudopotamilla reniformis (Bruguière, 1789) (16,408 bp) and comprised of two ribosomal RNAs, the ubiquitous set of 13 protein-coding sequences, and 22 tRNAs. The order of protein-coding genes is consistent with the proposed conserved pattern, which contradicts recent discovery in other members of the family (Sabella spallanzanii in Daffe et al., 2021 and Bispira melanostigma in Hornfeck et al., 2022). [ABSTRACT FROM AUTHOR]

Broodstock culture of Litopenaeus vannamei plays an important role in the shrimp culture industry; thus, a nutritional and bio-safety food for broodstock culture is necessary. Marine polychaetes, which have a good nutritional content, are an essential and widely used live food in the current shrimp industry. In this study, four polychaete species, Marphysa maxidenticulata, Cheilonereis cyclurus, Nereis vexillosa, and Perinereis aibuhitensis, were fed to broodstock of L. vannamei as the only food, and the gonadal maturity parameters of the broodstock were examined. The results showed that broodstock, which were fed with M. maxidenticulata, had the highest gonadal maturation rate (56.67%). The N. vexillosa food group had the highest gonadal index (5.37%). The content of serum progesterone and vitellogenin (VTG) was highest in the broodstock fed N. vexillosa. The expression of VTG mRNA in the gonads was also highest in the broodstock fed N. vexillosa, followed by those fed M. maxidenticulata. Nutritional content analysis showed that lipid content in the four worms ranged from 13% to 22%. The content of polyunsaturated fatty acids was highest in N. vexillosa, particularly C18:2 n-6, C18:3 n-3, C20:4 n-6, and C20:5 n-3. In addition, the 20:5 n-3 content in N. vexillosa was 2.5–8.0 times higher than that in the other polychaetes. These results indicated that polychaetes had different effects on promoting the gonadal maturation of L. vannamei. N. vexillosa and M. maxidenticulata could be potential live food to promote the gonadal maturation of L. vannamei.

Polychaete serves as aquafeed for most aquaculture species and as bioremediation agent of organic waste. Polychaete used for broodstocks of finfish and crustaceans stimulates gonadal maturation and endocrine system in penaeid shrimp, therefore overcoming the shortfall in juvenile production of animals and securing reliable production of aquaculture harvests. Commercial feed has gained the most ground in polychaete farming. Microalgae's essential nutrients and favorable morphology are ideal for polychaete larviculture. Home-made feed is less attractive due to its complex structural fibre but applicable as co-feed in polychaete nourishment. High organic matter waste is competitive as polychaete feed although it might lack adequate nutrients. The ideal feeds for polychaete growth, distinguished by the different life stages, are poorly studied. This review studies the fitness of microalgae in larviculture, nutritional value of commercial feed, and home-made feed as co-feed option, in polychaete nourishment; and the bioremediation benefit from polychaete's waste-feeding behaviour. [ABSTRACT FROM AUTHOR]

Introduction: The bivalve Semimytilus patagonicus is a potentially useful bioindicator because of its feeding mechanism, and the worm Pseudonereis gallapagensis is also interesting as a bioindicator because it is benthonic, abundant, and a food source for the squid Doryteuthis gahi. However, their sensitivity to contaminants has not been sufficiently studied. Objective: To test the usefulness of the mussel Semimytilus patagonicus and the polychaete Pseudonereis gallapagensis as ecotoxicological tools for detergents in the marine environment. Methods: We used 120 individuals of S. patagonicus from Miraflores and 120 of P. gallapagensis from Barranco (both near the city of Lima, Peru). For the bioassays, we used two anionic detergents (active ingredient, ai, Sodium Dodecylbenzene Sulfonate). For S. patagonicus, with an average valve length of 32.3 ± 6.4 mm, we tested “Double power Ariel®” (90 %) at concentrations of 17.5, 35, 70 and 140 mg ai l-1, evaluated after 48 and 72 h of exposure; and for P. gallapagensis, with a total body length of 20.4 ± 8.8 mm, we tested “Caricia®” at 62.5, 125, 250, 500 and 1 000 mg of ai l-1 at 24, 48 and 72 h of exposure. Results: The LC50 values (Mean Lethal Concentration) were 34.95 mg ia l-1 for S. patagonicus and 102.48 mg ia l-1 for P. gallapagensis at 72 h of exposure. The detergents were toxic for S. patagonicus and slightly toxic for P. gallapagensis. The risk classification for S. patagonicus is “harmful” and for P. gallapagensis “not classifiable”. Conclusions: These two bioindicators allow evaluating the acute toxicity of SDBS-based commercial detergents in the marine aquatic environment. [ABSTRACT FROM AUTHOR]

Polychaetes belonging to the genus Capitella are known to represent a complex of opportunistic cryptic species that dominates the macrobenthos of organically enriched sediments, such as muddy areas particularly rich in sulfide. With the exception of the species, Capitella capitata (Fabricius) from West Greenland, Capitella spp. from the European Atlantic coast have never been accurately characterized both genetically and morphologically and were often reported as capitata in the literature. The life cycle of these European worms has not been described properly either, despite their widespread use as bio-indicators in ecological studies. The present study provides the first morphological description of Capitella specimens collected along the Brittany coast and the English Channel up to the entrance of the North Sea and their genetic diversification in this region. Both morphological and molecular data are congruent and support the co-occurrence of cryptic species at the tip of Brittany. The most frequent French mt lineages, C-Channel1, C-Atlantic and C-Channel2, although well distinct from Capitella teleta, are also divergent but closer to C. capitata initially described from Greenland. Following barcoding, the most abundant species (C-Channel1) was isolated and reared in the laboratory to describe its life cycle and predict both its dispersal ability and ecological success in the face of the sulfidic muddy habitats of the French harbors. [ABSTRACT FROM AUTHOR]

Neanthes Kinberg, 1865 is a speciose nereidid genus with some species exhibiting epitoky during the timing of reproduction. The epitokal morphology of males and females has long been agreed to be diagnostic to distinguish species. In the present study, we provide redescriptions of the type material and reassess the current taxonomic status of four Neanthes species originally described based on the reproductive forms of specimens collected from Southeast Asia: Neanthes augeneri (Gravier & Dantan, 1934), N. gisserana (Horst, 1924), N. trifasciata (Grube, 1878) and N. trifasciata vandersandei (Horst, 1924). The non-metamorphosed and epitokous diagnostic features, including new characters found in this study, were used to redescribe and distinguish these species from other congeners. The four species are here recognised in Neanthes, whereby N. vandersandei is elevated to species level. Neanthes gisserana is considered as distinct from its previous senior synonym N. rubicunda (Ehlers, 1868). Morphology of both N. trifasciata and N. vandersandei, originally described based on mixed species, is restricted. Additionally, some remarks on the status of N. thysanota (Ehlers, 1908) are given. Distributional and reproductive data of the reviewed species are provided. An updated checklist of 80 valid species in Neanthes and synoptic tables of diagnostic features including the atokous and epitokous morphology are also presented. [ABSTRACT FROM AUTHOR]

Seven species of Pseudopolydora are described and illustrated from the Arabian Gulf, Kuwait: P. achaeta Radashevsky & Hsieh, 2000, P. antennata (Claparède, 1868), P. arabica Radashevsky & Al-Kandari, 2020, P. auha sp. nov., P. kuwaiti sp. nov., P. melanopalpa sp. nov., and P. multispinosa sp. nov. The morphology of the developed planktonic larvae is described for P. antennata and P. kuwaiti sp. nov. Adults of all species live in tubes in soft sediments, while adults of P. kuwaiti sp. nov. also bore in shells of gastropods and dead corals encrusted by coralline algae. Pseudopolydora antennata and P. arabica form dense settlements up to 50 000 individuals per 1 m2, while other species are comparatively rare. The phylogenetic relationships between the examined species and other Pseudopolydora (18 species in total) were assessed in an analysis of sequence data of four gene fragments: mitochondrial 16S rDNA, nuclear 18S rDNA and 28S rDNA, and Histone 3 (2473 bp in total). Three species complexes are distinguished involving P. antennata, P. diopatra Hsieh, 1992 and P. paucibranchiata (Okuda, 1937). Sets of adult morphological features shared by species of each complex and an identification key to Pseudopolydora species from the Arabian Gulf are provided.

Here, we present the first whole mitogenome sequence of the marine polychaete, Nereis zonata, isolated from the Beaufort Sea. The mitochondrial genome of N. zonata is 15,757 bp in length and consists of 13 protein-coding genes (PCGs), 22 transfer RNA (tRNA) genes, 2 ribosomal RNA (rRNA) genes, and a non-coding region that is typical of polychaetes. GC content of the N. zonata mitogenome is 37.2%. A maximum-likelihood gene tree based on the N. zonata mitogenome combined with previously published annelid mitogenome data revealed that N. zonata is clustered with Cheilonereis cyclurus, which form a sister group to Nereis sp.

Jombodin, T.; Songkai, P.; Wichachucherd, B., and Rodcharoen, E., 2021. The relationship between salinity and benthic fauna diversity and abundance at Songkhla Port, Thailand. Journal of Coastal Research, 37(6), 1173–1180. Coconut Creek (Florida), ISSN 0749-0208. Benthic fauna plays an important role in marine ecosystems as the primary food for other aquatic animals, and this animal group helps reduce sediment nutrients by filter feeding. The aim of this study was to evaluate and explain the diversity and abundance of the benthic fauna community at the Songkhla port, where both human activities and environmental fluctuations affect this community. Benthic fauna and water samples were collected at 2-month intervals from January to November 2017. The results show that most physical parameters had wide ranges and varied by month. The benthic fauna in the Songkhla lagoon was observed in this study. The results showed a higher number of taxa compared with a previous study. Three phyla, namely, Annelida, Arthropoda, and Mollusca, had 25 taxa recorded in this study. Crustaceans were the most diverse (nine taxa) and abundant (2981 ± 313 ind/m2) group, followed by polychaetes (eight families, 2350 ± 288 ind/m2) and mollusks (eight taxa, 633 ± 200 ind/m2). Barnacles were the dominant group of crustaceans (2153 ± 758 ind/m2), whereas Serpulidae (1864 ± 647 ind/m2) and Mytilidae (447 ± 367 ind/m2) were the dominant families of polychaetes and mollusks, respectively. Cluster analysis showed that the distribution of benthic fauna and physicochemical water quality varied with similar patterns. Clustering gave two groups: for rainy season from November to January and for dry season from May to November. According to canonical correspondence analysis, salinity and transparency were the main environmental factors associated with the distribution pattern of benthic fauna in the area. In conclusion, the activities at the Songkhla port have not yet created problems for marine benthic fauna; instead, seasonal changes appear to drive changes in benthic fauna. However, future construction developments can affect the geographical area, complementing stresses from parameter changes at local scales. [ABSTRACT FROM AUTHOR]

• Evidence for estrogen receptor signaling in lophotrochozoans is reviewed. • Lophotrochozoans of particular interest are annelids and rotifers. • Estrogen receptors are present and ligand activation in some lineages. • De novo synthesis of estradiol is not clearly established due to large data gaps. • Expression patterns for ER suggest roles in development, reproduction, digestion. Estrogen receptors (ERs) are thought to be the ancestor of all steroid receptors and are present in most lophotrochozoans studied to date, including molluscs, annelids, and rotifers. A number of studies have investigated the functional role of estrogen receptors in invertebrate species, although most are in molluscs, where the receptor is constitutively active. In vitro experiments provided evidence for ligand-activated estrogen receptors in annelids, raising important questions about the role of estrogen signalling in lophotrochozoan lineages. Here, we review the concordant and discordant evidence of estradiol receptor signalling in lophotrochozoans, with a focus on annelids and rotifers. We explore the de novo synthesis of estrogens, the evolution and expression of estrogen receptors, and physiological responses to activation of estrogen receptors in the lophotrochozoan phyla Annelida and Rotifera. Key data are missing to determine if de novo biosynthesis of estradiol in non-molluscan lophotrochozoans is likely. For example, an ortholog for the CYP11 gene is present, but confirmation of substrate conversion and measured tissue products is lacking. Orthologs CYP17 and CYP19 are lacking, yet intermediates or products (e.g. estradiol) in tissues have been measured. Estrogen receptors are present in multiple species, and for a limited number, in vitro data show agonist binding of estradiol and/or transcriptional activation. The expression patterns of the lophotrochozoan ERs suggest developmental, reproductive, and digestive roles but are highly species dependent. E 2 exposures suggest that lophotrochozoan ERs may play a role in reproduction, but no strong dose–response relationship has been established. Therefore, we expect most lophotrochozoan species, outside of perhaps platyhelminths, to have an ER but their physiological role remains elusive. Mining genomes for orthologs gene families responsible for steroidogenesis, coupled with in vitro and in vivo studies of the steroid pathway are needed to better assess whether lophotrochozoans are capable of estradiol biosynthesis. One major challenge is that much of the data are divided across a diversity of species. We propose that the polychaetes Capitella teleta or Platyneris dumerilii, and rotifer Brachionus manjavacas may be strong species choices for studies of estrogen receptor signalling, because of available genomic data, established laboratory culture techniques, and gene knockout potential. [ABSTRACT FROM AUTHOR]

While wastewater and paint particles discharged from the in-water cleaning process of ship hulls are consistently released into benthic ecosystems, their hazardous effects on non-target animals remain largely unclear. In this study, we provide evidence on acute harmful effects of hull cleaning wastewater in marine polychaete Perinereis aibuhitensis by analyzing physiological and biochemical parameters such as survival, burrowing activity, and oxidative status. Raw wastewater samples were collected during ship hull cleaning processes in the field. Two wastewater samples for the exposure experiment were prepared in the laboratory: 1) mechanically filtered in the in-water cleaning system (MF) and 2) additionally filtered with a 0.45 μm filter in the laboratory (LF). These wastewater samples contained high concentrations of metals (zinc and copper) and metal–based booster biocides (copper pyrithione and zinc pyrithione) compared to those analyzed in seawater. Polycheates were exposed to different concentrations of the two wastewater samples for 96 h. Higher mortality was observed in response to MF compared to LF–exposed polychaetes. Both wastewater samples dose-dependently decreased burrowing activity and AChE activity. Drastic oxidative stress was observed in response to the two wastewater samples. MDA levels were significantly increased by MF and LF samples. Significant GSH depletion was observed with MF exposure, while increased and decreased GSH contents were observed in LF-exposed polychaetes. Enzymatic activities of antioxidant components, catalase, superoxide dismutase, and glutathione S -transferase were significantly modulated by both wastewater samples. These results indicate that even filtered hull cleaning wastewater can have deleterious effects on the health status of polychaetes. [Display omitted] • Filtrated wastewater contained high concentrations of metals and metal-based antifoulants. • Filtered wastewater increased mortality, accompanied by a reduction of cholinergic system. • Even filtered wastewater acutely increased oxidative stress in a marine polychaete. [ABSTRACT FROM AUTHOR]

Pollution from personal care products, such as UV-filters like avobenzone and nano-zinc oxide (nZnO), poses a growing threat to marine ecosystems. To better understand this hazard, especially for lesser-studied sediment-dwelling marine organisms, we investigated the physiological impacts of simultaneous exposure to nZnO and avobenzone on the lugworm Arenicola marina. Lugworms were exposed to nZnO, avobenzone, or their combination for three weeks. We assessed pollutant-induced metabolic changes by measuring key metabolic intermediates in the body wall and coelomic fluid, and oxidative stress by analyzing antioxidant levels and oxidative lesions in proteins and lipids of the body wall. Exposure to UV filters resulted in shifts in the concentrations of Krebs' cycle and urea cycle intermediates, as well as alterations in certain amino acids in the body wall and coelomic fluid of the lugworms. Pathway enrichment analyses revealed that nZnO induced more pronounced metabolic shifts compared to avobenzone or their combination. Exposure to avobenzone or nZnO alone prompted an increase in tissue antioxidant capacity, indicating a compensatory response to restore redox balance, which effectively prevented oxidative damage to proteins or lipids. However, co-exposure to nZnO and avobenzone suppressed superoxide dismutase and lead to accumulation of lipid peroxides and methionine sulfoxide, indicating oxidative stress and damage to lipids and proteins. Our findings highlight oxidative stress as a significant mechanism of toxicity for both nZnO and avobenzone, especially when combined, and underscores the importance of further investigating the fitness implications of oxidative stress induced by these common UV filters in benthic marine organisms. [Display omitted] • Arenicola marina exposed to nZnO, avobenzone, and their combinations. • NZnO exposure triggers amino acid and energy metabolism alterations. • Metabolic shifts in both individual and combined exposures predominantly influenced by nZnO. • Single UV filter exposures enhance antioxidant defenses. • Concurrent nZnO and avobenzone exposure diminish antioxidants, leading to oxidative stress. [ABSTRACT FROM AUTHOR]

Here, we report the 15,103 bp mitochondrial genome of the freshwater fabriciid tubeworm Manayunkia occidentalis. We recovered 13 protein-coding genes, 2 rRNA, and 22 tRNA. The gene order is consistent with the conserved pattern observed in most annelids.

We reassess two specimens, part of the late Dr Minoru Imajima’s collections, from Japan of the flabelligerid genus Brada Stimpson, 1853. We re-identify the specimens as B. kudenovi Salazar-Vallejo, 2017 and newly record this species from Japan, which represents the southernmost locality of the genus worldwide. The specimens were previously reported as B. inhabilis (Rathke, 1843), which has Molde, Norway as its type locality. However, the morphological features are identical to the original description of B. kudenovi in the following: the body is whitish in alcohol; there are one or two multiarticulate notochaetae per parapodium; the neuropodial lobes are low, not projecting; and the body papillae are short.

Here, we sequenced and annotated the complete mitochondrial genome for the terebellid polychaete, Neoamphitrite affinis (Malmgren 1866). The complete mitogenome of N. affinis is 15,823 bp, with 33.4% A, 18.2% C, 11.5% G, and 37.0% T. The circular N. affinis mitochondrial genome comprises 13 protein-coding genes (PCGs), 23 transfer RNA (tRNA) genes including 2 methionine tRNA genes, 2 ribosomal RNA (rRNA) genes, and a non-coding region. Phylogenomic analysis based on 26 in-group taxa belonging to the two main clades, Sedentaria and Errantia, is congruent with published phylogenetic relationship for annelids, which N. affinis was grouped with Pista cristata (Terebellida; Terebellidae). This mitogenome resource will be useful for future phylogenetic studies of families belonging to Sedentaria. [ABSTRACT FROM AUTHOR]

The present study redescribes four species of Neanthes Kinberg, 1865 (Nereididae de Blainville, 1818) based on their type specimens collected from different worldwide localities: Neanthes chilkaensis (Southern, 1921) from India, N. galetae (Fauchald, 1977) from Panama, N. helenae (Kinberg, 1865) from St Helena Island, and N. mossambica (Day, 1957) from Mozambique. The morphology of the types was re-examined for the first time after the species were originally described, and incorporated the recent improvements in the standards and terminology for describing nereidid features. The arrangement of paragnaths on area VI stood out among the diagnostic features used to distinguish these four species. Neanthes chilkaensis and N. helenae are the unique nereidids bearing p-bar paragnaths on the area VI. Both species are also distinctive as the former species only exhibited p-bar paragnaths on the area VII–VIII and the latter ventrolateral projections on the apodous segment. Further examination revealed that N. nanciae (Day, 1949) from St Helena is a junior synonym of N. helenae. Moreover, N. galetae and N. mossambica are distinguishable from other species also by the development of dorsal cirri, neuropodial postchaetal lobe and ventral ligule, the presence/absence of merged paragnaths on area IV, paired oesophageal caeca, among other features. This study has further contributed to the morphological delimitation of the species in Neanthes as a first step towards revising the genus.

Our study aimed to evaluate the effect of trace element pollution in the polychaete Perinereis cultrifera (Grube, 1840) from two Tunisian coasts (the port of Rades, S1; and the Punic port of Carthage, S2). To this end, we used an approach based on proximate composition, biomarker responses and trace element bioaccumulation. Our results showed a decreasing order of metals concentrations (Zn>Cu>Cd>Pb) in P. cultrifera from S1 and S2. The accumulation of Cd, Cu and Zn was significantly higher in S1 than in S2, especially in summer. Lipid, protein and glycogen content also changed significantly between S1 and S2 in relation to trace metal accumulation and environmental conditions. The results revealed a higher level of thiobarbituric acid in P. cultrifera from S1 than from S2. In addition, the enzymatic and non-enzymatic antioxidant defence system (catalase, glutathione-S-transferase, superoxide dismutase, glutathione and metallothionein) was enhanced and acetylcholinesterase activities decreased in P. cultrifera in S1 in comparison with S2. A principal component analysis showed that P. cultrifera from S1 exhibited a clear disruption of oxidative stress responses and trace element bioaccumulation among seasons. Overall, these findings revealed the sensitivity of those organisms to environmental conditions.

Rhynchospio glandulosa sp. nov. inhabits silty tubes on muddy sand intertidally and in shallow water in the Yellow Sea, Sea of Japan (East Sea), and the Sea of Okhotsk (Korea, China, and Russia). Adults are up to 9 mm long, 1 mm wide for 62 chaetigers, with characteristic groups of glandular cells in the bases of branchiae from chaetiger 7 to chaetigers 14–23. Individuals with 29–40 chaetigers have mature spermatozoa in chaetigers 11–12 or 11–13, while larger worms are simultaneous hermaphrodites with sperm in chaetigers 11–14 and oocytes from chaetiger 16 to chaetigers 22–42. The oocytes are about 120 µm in diameter, with thin and smooth envelopes. The spermatozoa have a small subspherical acrosome about 1 µm long, a tusk-like nucleus 3–4 µm long, small midpiece with subspherical mitochondria, and a flagellum 45–47 µm long. Early larvae develop on the parent’s dorsum from chaetigers 21–27 to chaetigers 30–36, where they are loosely held by flat branchiae and long dorsal capillaries. After utilizing internal egg yolk, the 4-chaetiger larvae 250–280 µm long escape from the parent and continue its development in sea water, feeding on the plankton. About 2 weeks after hatching, the 11-chaetiger larvae 550–570 µm long get ready for settlement and metamorphosis. Rhynchospio glandulosa sp. nov. is one of the seven Rhynchospio species (12 species described so far) known as simultaneous hermaphrodites and one of the three species known to brood their larvae on the parent’s dorsum. The arrangement of male segments and sperm morphology are suggested as important taxonomic characters for the identification of Rhynchospio species. Feeding mechanism of the planktotrophic Spionidae larvae is briefly discussed. [ABSTRACT FROM AUTHOR]

This study deals with the macrobenthic assemblages and the biotic environmental quality of Kochi backwaters (KBW), India. Due to the heavy river discharge, extensive limnetic and turbid conditions prevailed in the KBW during the southwest monsoon (June to September). This exerted a profound adverse effect on the abundance, richness, and diversity of macrobenthic assemblages. Overall, mesohaline conditions with a clayey sand bottom substratum favored the high macrofaunal abundance during the southwest and northeast monsoon seasons. But mesohaline condition and sandy silt bottom were found to support high macrofaunal abundance in the KBW during the pre-monsoon season. Polychaete dominated the macrobenthic community, regardless of seasons. Capitella capitata, Heteromastus similis, Paraheteromastus sp., Prionospio cirrobranchiata, Minuspio cirrifera, Pagurapseudopsis kochindica, P. gymnophobia, Ctenapseudes indiana, C.chilkensis, Tanais sp., Villorita cyprinoides, Grandidierella sp., Ampelisca sp., and Littorina sp. were the dominant ones observed during the study. The sediment organic carbon, in general, showed a positive correlation with polychaete abundance during all three seasons. The ecological status of KBW during all three seasons was assessed as per BO2A index, which ranged from 0.05 to 0.18, suggesting a healthy to a moderately polluted bottom environmental condition. [ABSTRACT FROM AUTHOR]

A new species of the genus Travisia Johnson, 1840, the single genus of the family Travisiidae, is described. Specimens of Travisia sanrikuensis sp. nov. were collected in the Sanriku region, Japan, from the lower bathyal zone (871-1684 m depth) of the northwestern Pacific. Molecular phylogenetic analysis based on partial 16S rRNA gene sequences revealed that the new species is phylogenetically close to Travisia brevis Moore, 1923, but differs from all congeneric species by the following morphological characters: 25 segments, 20 chaetigers, and 19-20 pairs of cirriform branchiae starting from chaetiger 2. [ABSTRACT FROM AUTHOR]

Mass spawning dates of nyale worms (Eunicidae) have been scientifically predictable since 2019. However, the prediction of split spawning, i.e. the phenomenon when nyale worms spawn in both February and March, was made based on limited data. The present study aimed to revisit the dates of the split spawning prediction using the Metonic Cycle, i.e. 19-year lunisolar cycle. Using the existing prediction method 114 years of prediction dates were generated and then matched the dates with the Metonic Cycle. The results show that the spawning prediction dates generally follow the Metonic Cycle. There are only a few dates that need to be revised, i.e. when the full moon rises on the 14th of February. It is suggested that split spawning of worms is likely to occur when the full moon rises between the 7th to 13th of February. When the full moon appears before the 7th of February, single spawning will take place on the fifth day after March's full moon. When the full moon occurs after the 13th of February, single spawning will occur on the fifth day after February's full moon. The present work is the first study that demonstrates the relationship between nyale worms' spawning patterns and the Metonic Cycle. [ABSTRACT FROM AUTHOR]

The decorator worm Diopatra cuprea, a tube-forming marine polychaete common to intertidal and shallow subtidal waters, modifies habitats it occupies through microreef construction and algal gardening. While several studies have demonstrated that decorator worm tubes are hotspots of biogeochemical activity (i.e., nitrogen and sulfur cycling), it is still largely unclear whether the tube microbiome differs compositionally from the surrounding sediment and what distinct functional processes tube microbiomes may have. To address these unknowns, this study analyzed the bacterial communities of D. cuprea tubes and surrounding sediments using high-throughput 16S rRNA gene amplicon sequencing. Tubes and sediments were sampled at three sites along an anthropogenic stress gradient within the Newport River Estuary to also assess geographic variation of tube microbiomes and the possible influence of human disturbance. We found a clear distinction in the microbial community composition and diversity between tubes and surrounding sediment. Tube microbiomes were significantly enriched for the phyla Bacteriodetes, Actinobacteria, Verrucomicrobia, Deferribacteres, Latescibacteria, and Lentisphaerae. Chloroplast sequences of macroalgae and grass species were consistently abundant in tubes and nearly absent in surrounding sediment. Functional annotation of prokaryotic taxa (FAPROTAX)-based functional predictions suggested that tube microbiomes have higher potentials for aerobic chemoheterotrophy, sulfur compound respiration, nitrate reduction, methylotrophy, and hydrocarbon degradation than surrounding sediments. Tube microbiomes vary across sites, though dissimilarity is comparatively low compared to tube-to-sediment differences. Contrary to our hypothesis, the tubes at the most highly impacted site had the highest microbial diversity [i.e., amplicon sequence variant (ASV) richness and Shannon’s diversity], yet tubes from the medium impacted site actually had the lowest microbial diversity. Our findings show that D. cuprea tubes support a microbiome that is significantly distinct in composition and function from the surrounding sediment. Diopatra cuprea tubes appear to create unique microhabitats that facilitate numerous microbially-mediated biogeochemical processes in the marine benthic environment.

A new species of zoantharian within the genus Antipathozoanthus is described based on specimens collected from the coast of mainland Japan, northwest Pacific Ocean. Antipathozoanthus tubus sp. nov. is characterized by its substrate (epibiotic on polychaete tube) and habitat (exposed rock). As well, the results of molecular phylogenetic analyses using concatenated multiple genetic markers also support the distinction between A. tubus sp. nov. and its congenerics. Antipathozoanthus tubus sp. nov. is the first species of Antipathozoanthus species reported to be epibiotic on polychaete tubes, and is the second species in the genus that is not associated with antipatharians. [ABSTRACT FROM AUTHOR]

Trait assessment is an alternative but effective method of biomonitoring benthic community in ecosystem, but it was rarely done in Malaysia. An assessment was done to identify the dominant sub-traits, or modalities, within benthic community in seafloor northwards of Pulau Indah, Klang, Malaysia, and to establish possible correlation between modalities with environmental parameters measured in the area. Sampling was conducted in November 2018, during Northwest Monsoon season. Sediments were obtained by using a Ponar Grab and filtered through 500 µm sieve. Sediments were subjected into Loss of Ignition method to extract organic carbon, and filtration method to determine particle size distribution percentages. 37 taxa were recorded in this study, totalling to 848 individuals. Traits assessment indicated vermiform body shape, direct larval development, deposit feeder, non-motile, asexual reproduction, and second-order opportunistic group as most dominant modalities in the study area. Station 1 recorded highest macrobenthos density (21000 ind./m2), while station 5 recorded highest diversity (H’=2.19). Functional diversity (FD) for reproduction method was highest in station 1 (FD=0.61), ecological group in station 4 (FD=0.73); body shape (FD=0.56) and larval development (FD=0.63) in station 5, and lastly, adult mobility (FD=0.70) and feeding mode (FD=0.66) in station 6. Principal component analysis showed Station 1 has most modalities attributed towards it. Pearson correlation analysis suggested particle size distribution as major connector for most modalities (P=0.05). As BTA study is still new in Malaysian waters, it could serve as a good starting point for future assessment related to ecological functioning of benthic community in Malaysian seafloor. [ABSTRACT FROM AUTHOR]

Four Pseudopolydora Czerniavsky, 1881 species from European and adjacent waters are distinguished and a key to their identification is provided. Pseudopolydora antennata (Claparède, 1868) is redescribed based on material from the type locality, Gulf of Naples, Italy. Pseudopolydora pulchra (Carazzi, 1893) (type locality in the Gulf of Naples) is also redescribed based on material from Italy. Most previous records of the Asian P. paucibranchiata (Okuda, 1937) from North European waters are herein referred to a new species, P. nordica sp. nov. The latter differs from P. paucibranchiata by the absence of an occipital antenna on the prostomium and yellow ramified chromatophores on palps. Native to the Northwest Pacific, P. paucibranchiata was first recorded in European waters from the Tyrrhenian Sea, Lazio, Italy, in 1978. Since then, the species has spread widely in the Mediterranean and in 2015 was first recorded from northern Europe in the Netherlands. [ABSTRACT FROM AUTHOR]

Diopatra is the most species-rich genus of Onuphidae with about 60 species. Although 14 species have been reported for Brazil, the cosmopolitan D. cuprea is the most commonly reported from the area, including populations with a large morphological diversity. To better elucidate this species complex, we use morphological and molecular data, and reveal a hidden diversity. Thus, we describe four new species (D. hannelorae sp. nov. , D. marinae sp. nov. , D. pectiniconicum sp. nov. and D. victoriae sp. nov.) and discuss their geographical and bathymetrical distributions. None of the analysed specimens could be identified as D. cuprea based on available sequences. New taxonomic characters were highlighted, including jaw morphology, which was the determinant factor to differentiate D. marinae from D. victoriae. Phylogenetic analysis indicates three (COI and ND4) or four (concatenated) lineages, because D. marinae was not always reciprocally monophyletic. Sequence-based species delimitation also indicates three to five species, depending on the method used. Inter- and intragroup genetic divergence and haplotype network analysis supported four species. The divergence time among species indicates that Pleistocene sea-level fluctuations and the Vitória–Trindade chain limited the gene flow between northern and southern populations and contributed to the emergence of species, mainly in the case of D. marinae and D. victoriae. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The polychaete Diopatra claparedii Grube, 1878 is among those organisms successfully carrying out full body regeneration, including the whole nervous system. Thus, D. claparedii potentially can be regarded for the nervous system regeneration (NSR) study. However, data on the property of its nervous system and the NSR profile are still lacking. In this study, we investigated the morphology of D. claparedii anterior nervous system (ANS) and examined the cellular and molecular profiles on its early anterior NSR. The nervous system of D. claparedii consists of a symmetry brain with nerves branching off, circumpharyngeal connectives that connect the brain and nerve cord as well as obvious segmental ganglia. Moreover, we identified changes in the cellular condition of the ganglionic cells in the regenerating tissue, such as the accumulation of lysosomes and lipofuscins, elongated mitochondria and multiple nucleoli. Furthermore, mRNA of tissues at two regenerating stages, as well as intact tissue (non-regenerating), were sequenced with Illumina sequencer. We identified from these tissues 37,248 sequences, 18 differential expressed proteins of which upregulated were involved in NSR with noelin-like isoform X2 turned up to be the highest being expressed. Our results highlight the cellular and molecular changes during early phase of NSR, thus providing essential insights on regeneration within Annelida and understanding the neurodegenerative diseases.

Three different experiments were conducted to examine the oocyte development of the polychaete Hediste diversicolor in response to changing photoperiod and temperature at three different periods of oogenesis. In experiment I, worms collected during summer were reared under constant or decreasing photoperiod and temperatures to test the combined effects of the summer–autumn photoperiod and temperature transition on oogenesis. The result showed females collected during summer showed the highest oocyte growth when exposed to constant temperatures combined with decreasing photoperiod and decreasing temperature combined with constant photoperiod. In experiment II, worms collected in late autumn were under mimicked or shortened seasonal changes in photoperiod to evaluate the effect of accelerated change on oocyte growth. The result showed worms had 1.5 times faster oocyte growth rates when exposed to accelerated rate of change in photoperiod (2.5 times faster). In experiment III, worms collected in spring were exposed to different temperature regimes to examine the effect of raising temperature on the synchronization of oocyte growth and maturation. The results showed worms collected in spring showed increased temperatures will increase oocyte maturation synchronicity. It was concluded temperature and photoperiod transition can increase the oocyte development.

We describe a long-unnamed Chaetopterus Cuvier, 1830 species from southern California, using a combination of DNA barcoding and detailed morphological investigation employing high-resolution X-ray microtomography (micro-CT). Chaetopterus dewysee sp. nov. is not only one of the most dominant annelids in the benthic communities of the shallow end of the La Jolla submarine canyon, but also a well-established model for studying bioluminescence and has a published transcriptome. The description and naming of this southern Californian Chaetopterus is a step towards the much-needed revision of the group’s taxonomy and towards resolving the confusion over the ʻcosmopolitanʼ Chaetopterus variopedatus species complex. Micro-CT data showing details of both internal and external anatomy has been made freely available as the first annelid cybertype.

Chitin, one of the most abundant biopolymers in nature, is a crucial material that provides sufficient rigidity to the exoskeleton. In addition, chitin is a valuable substance in both the medical and industrial fields. The synthesis of chitin is catalyzed by chitin synthase (CHS) enzymes. Although the chitin synthesis pathway is highly conserved from fungi to invertebrates, CHSs have mostly only been investigated in insects and crustaceans. Especially, little is known about annelids from hydrothermal vents. To understand chitin synthesis from the evolutionary view in a deep-sea environment, we first generated the whole-genome sequencing of the parasitic polychaete Branchipolynoe onnuriensis. We identified seven putative CHS genes (BonCHS1-BonCHS7) by domain searches and phylogenetic analyses. This study showed that most crustaceans have only a single copy or two gene copies, whereas at least two independent gene duplication events occur in B. onnuriensis. This is the first study of CHS obtained from a parasitic species inhabiting a hydrothermal vent and will provide insight into various organisms’ adaptation to the deep-sea hosts.