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In May–June 2017 an expedition on board RV Investigator sampled benthic communities along the lower slope and abyss of Australia’s eastern margin from off mid-Tasmania to the Coral Sea. Over 200 annelids of the family Serpulidae collected during the voyage were collected and deposited in the Australian Museum in Sydney. Among them there was a new species of the poorly known abyssal (3754–4378 m) genus Spirodiscus. Serpulids typically build cylindrical calcareous tubes attached to hard substrates. Until now, only three serpulid species inhabiting free-lying polygonal tubes were reported from the deep sea: Spirodiscus grimaldii Fauvel, 1909 with quadrangular spirally coiled tubes, Bathyditrupa hovei Kupriyanova, 1993 with quadrangular tusk-shaped tubes, and Spirodiscus groenlandicus (McIntosh, 1877) with octagonal tusk-shaped tubes. The new species, S. ottofinamusi sp. nov. has very characteristic thin tusk-shaped unattached fluted tubes similar to those found in S. groenlandicus, but it differs by the details of collar, thoracic tori and abdominal chaetae. Morphologically, it has a pinnulated opercular peduncle and flat geniculate abdominal chaetae like filogranin serpulids but lacks thoracic Apomatus chaetae like serpulins. The first DNA sequences of this mysterious taxon places the new species within the filogranins in sister group relationship with Chitinopoma serrula.

A new species of Melinna (family Melinnidae) is described from the abyssal depths off the east coast of Australia. All material was collected during the RV Investigator voyage “Sampling the abyss” (IN2017_V03) in May–June 2017 from Bass Strait, Tasmania/Victoria using a beam trawl at 4197–4133 m depth. The new species Melinna hamulus sp. nov. differs from all other species of Melinna by having around 45 abdominal segments, dorsal membrane with 13–17 projections, four pairs of branchiae completely free and occurring in depths of over 4000 m. Phylogenetic relationships between our new species and other species within the family Melinnidae were assessed using the nuclear 18S and the mitochondrial 16S and cytochrome oxidase subunit I (COI) gene fragments. The results revealed that Melinna hamulus sp. nov. was genetically distinct from all other species of Melinnidae. This is the first species of Melinna to be described from Australian waters. We provide a new standard for description of species of Melinna and provide further detail on three existing species: Melinna albicincta Mackie & Pleijel, 1995, Melinna elisabethae McIntosh, 1914 and the type species of the genus Melinna cristata (Sars, 1851) using morphological characters illustrated with light and scanning electron microscopy photographs. We provide a table with the main diagnostic characters of all described species of Melinna together with type localities and depths.

Ficopomatus Southern, 1921 is a serpulid genus currently composed of six species, two of which (F. enigmaticus and F. miamiensis) are reef-builders. The former has invaded subtropical and warm-temperate estuaries worldwide, causing environmental and economic harm. In this study, Ficopomatus miamiensis and F. uschakovi are reported from brackish-water coastal localities in both Atlantic and Pacific sides of Mexico, including a Biosphere Reserve, estuaries, as well as shrimp and oyster farms. Ficopomatus miamiensis is reported from Veracruz (southern Gulf of Mexico, Mexico territory) and Sinaloa (southern Gulf of California). Ficopomatus uschakovi is reported for the first time in the southern Gulf of Mexico (Mexico territory) and repeatedly recorded in Chiapas (southern Mexican Pacific). There are no phenotypic differences between specimens of F. miamiensis from both coasts of Mexico. Comparison of mitochondrial cytochrome b (Cytb) DNA sequences further support the notion that F. miamiensis from the type locality (Florida) and Atlantic coasts of Mexico is also found along the Pacific coast of Mexico. Morphological variability within specimens of F. uschakovi from a single locality (either Laguna del Ostión or La Encrucijada) in Mexico suggest potential presence of multiple cryptic species. Molecular genetics studies are needed to confirm the taxonomic and invasive status of F. uschakovi.

The intertidal serpulid polychaete Spirobranchus kraussii was originally described from South Africa and has since been reported in numerous sub (tropical) localities around the world. Recently, however, S. kraussii was uncovered as a complex of morphologically similar and geographically restricted species, raising the need to revise S. cf. kraussii populations. We formally describe S. cf. kraussii from Singapore mangroves as Spirobranchus bakau sp. nov. based on morphological and molecular data. Despite their morphological similarities, Maximum Likelihood and Bayesian Inference analyses of 18S and Cyt b DNA sequence data confirm that S. bakau sp. nov. is genetically distinct from S. kraussii and other known species in the complex. Both analyses recovered S. bakau sp. nov. as part of a strongly supported clade (96% bootstrap, 1 posterior probability), comprising S. sinuspersicus, S. kraussii and S. cf. kraussii from Australia and Hawaii. Additionally, paratypes of S. kraussii var. manilensis, described from Manila Bay in the Philippines, were examined and elevated to the full species S. manilensis. Finally, we tested the hypothesis that fertilisation and embryonic development of S. bakau sp. nov. can occur under the wide range of salinities (19.6–30.9 psu) and temperatures (25–31°C) reported in the Johor Strait. Fertilisation success of ≥70% was achieved across a temperature range of 25–32°C and a salinity range of 20–32 psu. Embryonic development, however, had a narrower salinity tolerance range of 27–32 psu. Clarifying the taxonomic status of S. cf. kraussii populations reported from localities elsewhere in Singapore and Southeast Asia will be useful in establishing the geographical distribution of S. bakau sp. nov. and other members of the S. kraussii-complex.

Two new species, Melinnopsis gardelli sp. nov. and Melinnopsis chadwicki sp. nov. (Annelida, Ampharetidae, Melinninae), are described from deep waters off the east coast of Australia. One hundred and 11 specimens were collected during RV Investigator voyage IN2017_V03 in May–June 2017 using a beam trawl at lower bathyal depths (1000–2500 m). This is the first record of Melinnopsis from the eastern Australian coast. The two new species are morphologically similar, but differ by methyl blue staining pattern, shape of thoracic uncini and pigmented glandular bands above the nuchal slits. Melinnopsis gardelli sp. nov. has a conspicuous stained band on the dorsum ending between chaetigers 9 and 10, uncini with three teeth above the rostral tooth and lacks glandular bands, while M. chadwicki sp. nov. has a faint stained band on the dorsum ending at chaetiger 5, uncini with two teeth above the rostral tooth and possesses glandular bands. They also show differences in bathymetric distribution as M. gardelli sp. nov. was collected around 2500 m and M. chadwicki sp. nov. around 1000 m depth. Phylogenetic relationships among the new species and other members of the family Ampharetidae were assessed using the nuclear 18S and the mitochondrial 16S and cytochrome oxidase subunit I (COI) gene fragments. The results revealed that M. gardelli sp. nov. and M. chadwicki sp. nov. form a monophyletic clade and are genetically distinct from each other and all other analysed species. This is the first time molecular data have been used to describe a species in the genus Melinnopsis. publishedVersion

We report the mitochondrial genome of Sabella spallanzanii, an invasive Mediterranean sabellid introduced to Australia and New Zealand. The mitogenome is 15,581 bp long and consists of 38 genes, including 13 protein coding genes, two rRNA genes, and 23 tRNA genes. It shows deviations from the putative annelid ground pattern, such as gene order re-arrangements and regions encoding on the negative strand. It is, however, very different from the mitogenome of the closely related serpulid, Spirobranchus giganteus. Phylogenetic analyses of the mitochondrial genes support a sister relationship of Sabella spallanzanii and Spirobranchus giganteus.

In Australia, the deep-water (bathyal and abyssal) benthic invertebrate fauna is poorly known in comparison with that of shallow (subtidal and shelf) habitats. Benthic fauna from the deep eastern Australian margin was sampled systematically for the first time during 2017 RV ‘Investigator’ voyage ‘Sampling the Abyss’. Box core, Brenke sledge, and beam trawl samples were collected at one-degree intervals from Tasmania, 42°S, to southern Queensland, 24°S, from 900 to 4800 m depth. Annelids collected were identified by taxonomic experts on individual families around the world. A complete list of all identified species is presented, accompanied with brief morphological diagnoses, taxonomic remarks, and colour images. A total of more than 6000 annelid specimens consisting of 50 families (47 Polychaeta, one Echiura, two Sipuncula) and 214 species were recovered. Twenty-seven species were given valid names, 45 were assigned the qualifier cf., 87 the qualifier sp., and 55 species were considered new to science. Geographical ranges of 16 morphospecies extended along the eastern Australian margin to the Great Australian Bight, South Australia; however, these ranges need to be confirmed with genetic data. This work providing critical baseline biodiversity data on an important group of benthic invertebrates from a virtually unknown region of the world’s ocean will act as a springboard for future taxonomic and biogeographic studies in the area.

Background Our knowledge of the benthic fauna at lower bathyal to abyssal (LBA, > 2000 m) depths off Eastern Australia was very limited with only a few samples having been collected from these habitats over the last 150 years. In May–June 2017, the IN2017_V03 expedition of the RV Investigator sampled LBA benthic communities along the lower slope and abyss of Australia’s eastern margin from off mid-Tasmania (42°S) to the Coral Sea (23°S), with particular emphasis on describing and analysing patterns of biodiversity that occur within a newly declared network of offshore marine parks. Methods The study design was to deploy a 4 m (metal) beam trawl and Brenke sled to collect samples on soft sediment substrata at the target seafloor depths of 2500 and 4000 m at every 1.5 degrees of latitude along the western boundary of the Tasman Sea from 42° to 23°S, traversing seven Australian Marine Parks. Results The biological sampling included 35 beam trawls, 28 Brenke sleds, 8 box cores, 20 surface meso-zooplankton tows, and 7 Deep Towed Camera transects. In total, 25,710 specimens were identified to 1084 taxonomic entities, including 847 species-level, 144 genus-level and 69 family-level and 24 higher-level taxa. Of the species-level taxa, only 457 were assigned species-level taxonomic names, which implies that up to 58% of the collected fauna is undescribed. In addition, the ranges of numerous species have been extended to include the western Tasman Sea. Conclusions The lower bathyal and abyssal fauna of soft sediment seafloors off eastern Australia has been systematically surveyed for the first time. The resultant collections will provide the foundation for much future ecological, biogeographical, phylogenetic and taxonomic research.

In May–June 2017 an expedition on board RV ‘Investigator’ sampled benthic communities along the lower slope and abyss of eastern Australia from off Tasmania to the Coral Sea. Over 200 sabellariid specimens of the genera Phalacrostemma and Gesaia were collected during the voyage and deposited in the Australian Museum. Here we describe two new species Gesaia csiro n. sp. (4414–4436 m) and Phalacrostemma timoharai n. sp. (1013–1093 m). We did not formally describe another species of Phalacrostemma due to poor condition of the single specimen. Gesaia csiro n. sp. is the first record of the genus from Australian waters (only a planktonic larva attributed to the genus has previously been recorded), and it can be distinguished from other congeners by the smooth surface of inner paleae, distal thecae of outer paleae with long, irregular and expanded distal fringe and circled distal margin. Phalacrostemma timoharai n. sp. differs from congeners by the following combination of characters: presence of the buccal flap, absence of tentacular filament, 18–22 pairs of outer paleae, two pairs of neuropodial cirri on first thoracic segment, and only one pair of lateral lobes on second thoracic segment. Morphological descriptions are accompanied by mitochondrial cytochrome c oxidase subunit 1 (COI) and ribosomal (16S, 18S and 28S) sequence data. A key to all Australian species of sabellariids is given.

A recent study (Simon et al. 2019) confirmed that Spirobranchus kraussii is neither a widely distributed tropical species of Indo-Pacific origin nor a Lessepsian migrant to the Mediterranean, but a large complex of species, some of which might be indeed invasive. Thus, a common intertidal gregarious serpulid, previously attributed to S. kraussii in the Persian Gulf and Gulf of Oman, is described herein as Spirobranchus sinuspersicus sp. nov., using a combination of morphological and molecular data. The new species differs from S. kraussii by smaller size, fewer abdominal chaetigers, arrangement of abdominal chaetae and shape of opercular endplate talon. Results of phylogenetic analyses of a dataset combining 18S nucleotide and Cyt-b amino-acid sequences of S. sinuspersicus sp. nov. and Spirobranchus spp. available from GenBank supported monophyly of S. kraussii complex (including S. cariniferus) nested within Spirobranchus and thus, provided molecular support for synonymy of Pomatoleios with Spirobranchus proposed based on morphological criteria. The new species forms a well-supported clade with (S. kraussii (sp. 2 Hawaii + sp. 3 Australia)) clade, which in turn forms a clade with Spirobranchus sp.1 from temperate Japan, while S. cariniferus from New Zealand forms a basal grade. Evidence of substitution saturation of Cyt-b nucleotide sequences suggests that using translated amino-acid sequences to exclude non-informative substitutions should provide a better phylogenetic resolution for the genus Spirobranchus. Further studies are required to determine the invasive status of S. sinuspersicus sp. nov. as well as taxonomic and invasive status of S. cf. kraussii populations from the Mediterranean Sea, Suez Bay, Pakistan, India, Sri Lanka, Philippines, Singapore, and Panama.

Mitochondrial genomes are frequently applied in phylogenetic and evolutionary studies across metazoans, yet they are still poorly represented in many groups of invertebrates, including annelids. Here, we report ten mitochondrial genomes from the annelid genus Hydroides (Serpulidae) and compare them with all available annelid mitogenomes. We detected all 13 protein coding genes in Hydroides spp., including the atp8 which was reported as a missing gene in the Christmas Tree worm Spirobranchus giganteus, another annelid of the family Serpulidae. All available mitochondrial genomes of Hydroides show a highly positive GC skew combined with a highly negative AT skew – a feature consistent with that found only in the mitogenome of S. giganteus. In addition, amino acid sequences of the 13 protein-coding genes showed a high genetic distance between the Hydroides clade and S. giganteus, suggesting a fast rate of mitochondrial sequence evolution in Serpulidae. The gene order of protein-coding genes within Hydroides exhibited extensive rearrangements at species level, and were different from the arrangement patterns of other annelids, including S. giganteus. Phylogenetic analyses based on protein-coding genes recovered Hydroides as a monophyletic group sister to Spirobranchus with a long branch, and sister to the fan worm Sabellidae. Yet the Serpulidae + Sabellidae clade was unexpectedly grouped with Sipuncula, suggesting that mitochondrial genomes alone are insufficient to resolve the phylogenetic position of Serpulidae within Annelida due to its high base substitution rates. Overall, our study revealed a high variability in the gene order arrangement of mitochondrial genomes within Serpulidae, provided evidence to question the conserved pattern of the mitochondrial gene order in Annelida and called for caution when applying mitochondrial genes to infer their phylogenetic relationships., The study was mainly funded by Australian Biological Resources Study (ABRS) grants RF213-19 and RG18–21 to EKK and an International Macquarie University Research Excellence Scholarship (iMQRES) from Macquarie University to YS. The data analysis and paper writing were partly supported by Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou) (GML2019ZD0404, GML2019ZD0409, L20190005) to JWQ and by French State in the frame of the “Investments for the future” Programme IdEx Bordeaux (ANR-10-IDEX-03-02) to GD.

The Mediterranean fan worm,Sabella spallanzanii(Gmelin, 1791), is a highly invasive pest species introduced to Australia and New Zealand, with the ability to alter marine ecosystems by outcompeting native species for food and space.Sabella spallanzaniihas been established in southern Australia for decades, but was discovered in Botany Bay (NSW, eastern Australia) in 2013. In New Zealand,S. spallanzaniiwas first detected in March 2008. Using cytochrome c oxidase subunit 1 (COI) sequences, we investigate the phylogeography of the Australian and New Zealand populations ofS. spallanzanii, including the possible origins of the recent incursions in both countries. Australian and New ZealandS. spallanzaniishow minimal genetic diversity (0.2% divergence) and were dominated by two main haplotypes suggesting a commonality. Our molecular data are insufficient by themselves to identify fine-scale invasion pathways in antipodeanS. spallanzanii, but the similar, minimal haplotype diversity in combination with well-constrained field survey data suggests that the New Zealand incursion originated from southern Australia, rather than as a new incursion from the Mediterranean Sea. This highlights the importance of ongoing marine biosecurity surveillance and monitoring as well as improvements to biosecurity protocols for international and domestic vessels. The origin of the eastern Australian (Botany Bay) incursion is plausibly derived from either southern Australia or as a ‘return’ from New Zealand, and requires further, more detailed investigation.

As a service to taxonomists and ecologists using names in the well-known and species-rich ship-fouling serpulid genus Hydroides we present an update of all 107 non-synonymised scientific names, with additional information on Hydroides nomenclature, original names, etymologies, and type localities derived from original literature, and in accord with the World Register of Marine Species (WoRMS) database. An update is needed because the gender of genus Hydroides has from 1 January 2000 reverted to the original feminine, due to a change in the wording of International Code of Zoological Nomenclature which was overlooked at that time, and is contrary to the usage in practice of Hydroides as masculine which had started about 1992, although Code-required from the 1960s. We match 31 further original names of current WoRMS subjective junior synonyms to each non-synonymised name, and also report on the world distribution of the genus as illustrated by type localities of the valid names. We include notes on seven species inquirenda. The correct rendering is given of six names that have been altered for gender agreement for the first time herein. Hydroides gottfriedi nom. n. replaces junior homonym Hydroides rostrata Pillai, 1971. Currently there are 41 non-synonymised species-group names in Hydroides which should be gender invariant, and 23 names which would only change if moved to a neuter genus; the remaining 43 names are fully gender variable. Place-names (23), and personal names (16) make up more than a third (36%) of the species names, with most of the remainder (68) being descriptive of species character states, usually of operculum morphology (54). All species, except Hydroides norvegica (63°N), have type localities in shallow-water coastal locations in temperate to tropical waters below latitude 44°, with the highest number of new species (54) from the adjoining Western Pacific and Indian Ocean areas. The other concentration of new species (31) are those first found on the Pacific and Atlantic coasts of North America and in the Caribbean.

A new species of the Marphysa sanguinea group, M. iloiloensis n. sp. (Annelida: Eunicida: Eunicidae), is described from the Marine Annelids Hatchery of the Southeast Asian Fisheries Development Center, Aquaculture Department (SEAFDEC- AQD), Iloilo Province, Philippines. It represents the first record of this group in the Philippines. The new species is most similar morphologically to M. hongkongensa Wang, Zhang & Qiu, 2018, but can be distinguished from it by having fewer branchial filaments, a pair of faint eyes (absent in M. hongkongensa), and in slight differences in jaw morphology and chaetation. The embryos of the new species develop inside a jelly cocoon attached to the entrance of the adult burrow; this is the first time that egg-containing cocoons have been found in any species of the sanguinea-group. Phylogenetic analysis based on the mitochondrial gene cytochrome c oxidase subunit I (COI) revealed that Marphysa iloiloensis n. sp. is genetically distinct from all other analysed Marphysa species and forms a sister group to M. hongkongensa. A revised identification key to members of the sanguinea-group in Southeast Asia is provided.

Petta Malmgren, 1866 is a small and poorly known genus of the annelid family Pectinariidae Quatrefages, 1866. Prior to this study, the genus comprised four species P. pusilla Malmgren, 1866 (type locality Gullmarsfjord, west coast of Sweden), P. assimilis McIntosh, 1885 (type locality between Prince Edward and Kerguelen Island, southern Indian Ocean), P. pellucida (Ehlers, 1887) (type locality Santarem Channel between Cay Sal Bank and Bahamas, Caribbean Sea) and P. tenuis Caullery, 1944 (type locality Sulu, Philippines, tropical Pacific Ocean), the two last ones were known only from the original description. We revised the genus by re-examining the types and providing updated illustrated re-descriptions of its species, except for P. assimilis of which the type material has been lost. Commonly used morphological characters of the genus are expanded to also include new ones such as the presence of pair of lateral ear-shaped lobes adjacent to dorsal base of cephalic veil, pair of ventral lappets on segment 1, pair of dorso-lateral pads on segment 5, large basal hump on branchiae, and a rounded anterior peg with a blunt tip and a longitudinal row of two major teeth on uncini. The type species P. pusilla is recognised as having four lappets on the anterior margins of cephalic veil and a large lower lip posterior to buccal cavity. Two species P. investigatoris n. sp. and P. williamsonae n. sp. are described from deep water off the coast of southeastern Australia and represent the first records of this genus in Australian waters. A phylogenetic position of one new species was assessed in the framework of a phylogeny based on a fragment of the mitochondrial cytochrome oxidase I gene (mtCOI). An updated taxonomic key to Pectinariidae genera and all species of Petta is given.

Introduction of non-native species threatens local marine biodiversity, generating substantial costs for the aquaculture and tourism industries when native (including commercial) species are displaced. It is important that non-indigenous species are identified and controlled before they establish locally becoming invasive pests. The important vectors contributing to human-related dispersal of marine species include ship hull biofouling, ballast water and the aquaculture trade. Among over 80 polychaete families, fouling (Serpulidae and Sabellidae) and burrowing (Spionidae) worms are most commonly introduced to new localities. To assist in identification of potentially invasive non-native polychaetes, a web-based guide fully illustrated with original photographs was developed at the Australian Museum. The guide covers 66 species including 38 species of Serpulidae, 14 species of Sabellidae, and 14 species of Spionidae. This guide is intended for use by biologists, environmental consultants, quarantine officers and port management authorities as correct identification of species is essential for marine pest monitoring and management. The “Polychaete Identifier” will be extended to include other potentially invasive marine species of polychaetes, as well as crustaceans and molluscs in the near future, subject to funding availability.

A newly established population of the fouling polychaete Spirobranchus cf. tetraceros is reported from the western Mediterranean (Valencia Port). Despite previous intensive surveys, this is the first record for the taxon in the Iberian Peninsula. Molecular analyses revealed that S. cf. tetraceros from Valencia are genetically identical to specimens from Heraklion, Crete, but different from those collected in the Red Sea and S. tetraceros sensu stricto from the type locality in Australia. Mediterranean and Red Sea S. cf. tetraceros form a well-supported monophyletic clade but are clearly distinct from New South Wales specimens of S. tetraceros. Our new molecular evidence supports the hypothesis that S. tetraceros is not a global invader of Australian origin but rather a large species complex in need of a comprehensive worldwide revision. These results highlight the importance of integrative taxonomic research for species with reported global distributions because these taxa may include cryptic invaders. An illustrated morphological account of the Valencia and Heraklion specimens and a taxonomic key for Spirobranchus species in the Mediterranean Sea are provided.

Background The Great Australian Bight (GAB) comprises the majority of Australia’s southern coastline, but to date its deep water fauna has remained almost unknown. Recent issuing of oil and gas leases in the region has highlighted this lack of baseline biological data and established a pressing need to characterise benthic abyssal fauna. Methods From 2013 to 2017, six large-scale systematic surveys of the GAB were conducted from 200 to 5000 m depth, constituting the deepest systematic biological sampling in Australia. Sampling was conducted on soft sediment and hard substrates, both at pre-determined depth intervals along north-south transect lines and at sites of interest identified by multibeam sonar. Results A total of 66,721 invertebrate specimens were collected, comprising 1267 species, with 401 species (32%) new to science. In addition to the novelty of the fauna, there was a high degree of rarity, with 31% of species known only from single specimens. Conclusions In this paper, we provide an annotated checklist of the benthic invertebrate fauna of the deep GAB, supplemented with colour photos of live specimens and commentary on taxonomy, diversity and distributions. This work represents an important addition to knowledge of Australia’s deep sea fauna, and will provide the foundation for further ecological, biogeographical and systematic research.

Two new species of Marphysa Quatrefages, 1865 (Polychaeta: Eunicida: Eunicidae), M. bulla n. sp. and M. maxidenticulata n. sp., are described from the northern coast of China with comments on the usefulness of pectinate chaetae to separate species. A redescription of Marphysa orientalis Treadwell, 1936 originally described from China is given. The genus Marphysa is widely collected for bait for recreational fishermen and anglers in China and is also exported to Australia and Japan, yet the number of species involved or their native distribution are currently unknown. It is critical that aquaculture programs know which species they are attempting to breed and their native distributional ranges. A key to all described species of Marphysa from China, including two new species described in this paper is given.

Members of the tubicolous polychaete family Serpulidae constitute one of the most important groups of marine fouling biota. This paper describes a new species of the serpulid genusHydroidesfrom dock fouling at Mazatlán (southern Gulf of California), providing information about live colouration and reproductive features.Hydroides dolabrussp. nov. belongs to a subgroup of species in which verticil spines are equal in size and shape, lack both external and lateral spinules, but have various modifications to their tips. However,Hydroides dolabrussp. nov. is distinct in having tips of verticil spines pickaxe-shaped, with asymmetrical triangular radially orientated projections: the internal projections are short and point inward the verticil centre, while longer external projections point outward the verticil centre. Like all species of the genus,H. dolabrussp. nov. is a gonochoristic broadcast spawner lacking sexual dimorphism. A phylogenetic analysis of Hydroides based on COI, 18S and cytbsequence data reveals thatH. dolabrussp. nov. is genetically distinct from other species ofHydroidesfor which sequence data are available. The new species is the 11th in the genus described from Mexican waters.

Hydroides is a large and diverse group of calcareous tubeworms (Serpulidae, Annelida) recognised by a distinctive but variable two-tiered operculum. Despite considerable research using several species of Hydroides as models in ecological and biofouling studies, phylogenetic and biogeographic relationships within the genus are still poorly understood. Using combined mitochondrial (COI, cytochrome b) and nuclear (18S, 28S and ITS) gene markers for 284 individuals of 45 morphospecies of Hydroides, we investigated the global phylogenetic and biogeographic relationships within the genus. Phylogenetic topologies were well supported and indicated high genetic diversity within Hydroides, revealing potential cryptic species. Present results also include the first COI barcoding data enabling rapid and effective species identification of Hydroides on a global scale. Phylogenetic relationships within Hydroides were more concordant with geographical distributions than morphological similarity of their opercula. Molecular divergence estimates suggested the origin and subsequent diversification in the western Tethys Sea followed by a shift of the historical centre of diversity from the Indo-Mediterranean region to the central Indo-Pacific during the last 50 million years. Further studies on population genetics of species consisting of multiple lineages would provide a better understanding on the status of potential cryptic species. Furthermore, paleogeographic studies based on fossil Hydroides tubes would provide evidence to test this biogeographic hypothesis.

Clarifying taxonomic status is essential to understanding invasion source and the spread of invasive species. Here we used barcoding gene cytochrome c oxidase subunit I to explore the issue in a common fouling invasive species Hydroides dianthus. The species was originally described from off New England, USA, reported along the east coast of North America down to Florida and the Caribbean region, introduced to China, Europe, Japan and West Africa via anthropogenic transport and is now collected in Brazil for the first time. Unlike most congeners, H. dianthus has tolerance for a wide temperature range, being distributed from temperate to subtropical waters. Our results based on 112 specimens collected from 17 localities worldwide confirmed that H. dianthus sensu stricto is indeed a global invader. Observed higher haplotypes diversity in the Mediterranean seems to contradict the currently accepted native range of H. dianthus sensu stricto in the USA. The study also revealed the existence of a potential cryptic species H. cf. dianthus with a genetic distance of 5.6%. The cryptic lineage found in Texas was evidently introduced to the Black Sea only recently. Given that both lineages within H. dianthus are invasive, a greater emphasis on adequate monitoring and management of the routes responsible for introductions of this species is needed.

Ficopomatus enigmaticus (Fauvel, 1923) is a reef-building serpulid polychaete that has invaded estuaries worldwide, causing environmental and economic harm. Although Australia has long been suggested as a place of origin for the species, this remains unclear. We tested for genetic patterns across the range of F. enigmaticus in southern Australia, predicting that if the species is an Australian native, it would show evidence of (east-west) phylogeographic patterns often observed in native marine species in southern Australia. Unexpectedly, concordant patterns from mitochondrial (Cyt B) sequencing and nuclear marker (iSSR) profiles suggested the presence of at least three genetic groups (putative species), not distributed simply as "east" or "west". Two common (and closely related) groups were present across Australia and were often found together in the same aggregations. A third group was only found in southeast Australia and was morphologically similar to F. uschakovi (Pillai, 1960), a species previously reported from tropical areas. The discovery of multiple cryptic species with overlapping ranges means that more work is needed to resolve whether any of the F. enigmaticus sensu lato group has an Australian origin and to determine how they are related to invasive populations of F. enigmaticus elsewhere. Refereed/Peer-reviewed

In 1973, Vance published a mathematical model that explains differences in reproductive strategies such as planktotrophy and lecithotrophy found in marine invertebrates. The original model Vance (The American Naturalist, 107, 339–352) traded fecundity against development time and resulted in a U-shaped fitness function suggesting that only extreme levels of egg provisioning (referred to as egg size) are evolutionarily stable. Several later models independently predicted evolutionary stability of extreme egg sizes, and this has been commonly interpreted as a proof that the Vance model, albeit oversimplified, reflects the fundamental evolutionary principle of disruptive egg size evolution in marine invertebrates. However, empirical studies of the last several decades have illustrated that intermediate levels of egg provisioning are commonly observed in nature. As a result, the recent modifications of the original Vance model have attempted to explain evolution of such intermediate strategies. Here we re-examine the earlier fecundity-time models of the ‘Vance family’ and show that only Vance and its minor modification by Grant (The American Naturalist, 122, 549–555) invariably predict evolutionary stability of extreme egg sizes. Most modifications of the original Vance model in fact can predict at least some intermediate optimal egg sizes and reproductive strategies. There is no reason to assume that selection towards extreme egg sizes is the driving force in the evolution of marine invertebrate life histories.

Although the carbonate compensation depth (CCD) for calcite, generally located in the depth range 4000–5000 m, is often proposed as a physiological barrier to deep-ocean colonization, many organisms with calcareous exoskeletons are found in the deepest oceanic trenches. Serpulid polychaetes inhabiting unprotected calcareous tubes are unlikely deep-sea inhabitants, yet, they are found at all oceanic depths from intertidal to hadal. Here we review and revise the published and unpublished records of Serpulidae from below 5000 m depth. We also describe tube ultrastructure and mineralogical content of available deep-sea serpulid tubes to obtain insights into their biomineralisation. Species belonging to the genera Bathyditrupa, Bathyvermilia, Hyalopomatus, Pileolaria (spirorbin) and Protis were found at depths from 5020 to 9735 m. However, only specimens of Protis sp. were truly hadal (>6000 m) being found at 6200–9700 m. Hadal specimens of Protis have irregularly oriented prismatic tube microstructure similar to that found in more shallow-water representatives of the genus. Initial EDX analysis suggested a mostly calcitic composition (i.e., the most stable CaCO3 polymorph) on the basis of high Mg levels. Surprisingly, however, tubes of Bathyditrupa hovei and a species of Protis analysed using the more reliable method of laser Raman spectroscopy were found to be composed of aragonite. The compensation depth for this less stable CaCO3 polymorph in the oceans is usually 2000–3000 m. We found no obvious structural adaptations to life at extreme depths in the studied serpulid tubes and how serpulids are able to biomineralise and maintain their tubes below the CCD remains to be explained.

Chaetae are continually being replaced during the life of a polychaete, but the process of chaetal degeneration during replacement is still poorly known. Chaetal loss occurs either one at a time through special degenerative sites, or all chaetae in a chaetal sac are lost simultaneously in the absence of degenerative sites. Old chaetae can be either resorbed inside the coelom or shed. This study describes chaetal degradation, loss, and subsequent replacement during experimentally induced regeneration in the sabellid polychaete Pseudopotamilla reniformis. During post-traumatic regeneration in P. reniformis, abdominal-type chaetae fall from the chaetal sac simultaneously without degenerative sites, and are replaced by thoracic-type chaetae. Chaetal sac degradation occurs in three main stages: (1) formation of numerous lysosomes and small electron-transparent vesicles in follicle cell cytoplasm; (2) disintegration of follicular cell membranes; and (3) disintegration of follicular cell cytoplasm. Description of changes during parapodial transformation allows identification of signs of degradation that can serve as histological indicators of chaetal degeneration in a wide range of polychaetes. Our study suggests that chaetal degeneration and loss in polychaetes can occur either with degenerative sites or without them, depending on the type of chaetal replacement.

A well-illustrated glossary supports the study of polychaete anatomy and systematics, as well as aiding species identification, a need that emerged within the shipping and aquaculture industries over recent decades. Sabellidae, Serpulidae and Spionidae are polychaete families that most often include species that are translocated globally through ship fouling, ballast water or aquaculture trade. Accurate identifications are crucial since these translocations have significant ecological and commercial implications and also for phylogenetic and other biological studies. Using digital illustrations of specimens (deposited predominantly at the Australian Museum in Sydney), a glossary has been developed for these three families with the aim of standardising terminologies. Complete-focus images were generated with Helicon Focus 5.3 Pro software from multiple image layers. The definitions have been explained specific to families and illustrated with these images, thus creating the first comprehensive, digitally illustrated glossary of polychaete terminology.

An early mathematical model of egg size evolution in marine invertebrates (American Naturalist, 1973a, 107, 353) traded fecundity against development time and resulted in a U-shaped optimality curve suggesting that only extremes of egg sizes should be evolutionary stable. It was later suggested that the model predicts a bimodal distribution of egg sizes and therefore can be tested by examining histograms of egg sizes. More recent fecundity-time models (American Naturalist, 1997, 150, 48; American Naturalist, 2000, 156, 175) came up with predictions of intermediate optimal egg sizes; however, comparisons of optimality curves with histograms of egg sizes remained central to model testing. Here the question whether the bimodality assumption has any basis has been addressed theoretically. Simulation modeling and analysis show that egg size distributions generally do not match the optimality curves produced by fecundity-time models and that the shape of predicted frequency distributions depends on both the optimality curve and other model parameters. Therefore, egg size frequency distributions alone cannot be used for model testing.

Although Scandinavian Arctic polychaete fauna has been extensively investigated, new species are still being found in the Barents Sea. Polychaetes of the family Serpulidae are calcareous tubeworms that are most abundant at low latitudes and less common in Arctic and Antarctic waters. Because recent phylogenetic data indicate that the family Spirorbidae is a clade nested inside Serpulidae, spirorbins are treated here as subfamily Spirorbinae and their traditionally recognized subfamilies are thus lowered to the tribes Paralaeospirini, Spirorbini, Circeini, Romanchellini, Pileolariini and Januini. Here we report two new serpulid species, a filogranin Protis akvaplani sp. n. and a spirorbin Bushiella ( Bushiella ) barentsii sp. n. collected from off the northern Norwegian coast. Protis akvaplani differs from other species of within the genus by its tube with a high longitudinal keel, six thoracic chaetigerous segments, and short thoracic membranes ending after the 3rd segment. Generic diagnosis of the genus Protis has been emended. Bushiella ( B. ) barentsii differs from other species of the subgenus Bushiella by morphology of the opercular talon of operculum, incomplete fusing of primary operculum with brood chamber, and large tubes (up to 5 mm in coil diameter) with 1-2 distinct longitudinal ridges.

The tube-dwelling polychaete Pseudopotamilla reniformis (Sabellidae) forms dense and complex aggregations of flexible tubes on hard substrates in the subtidal zone of the White Sea. No sexual reproduction was observed in this study and recruitment appeared to be due to asexual reproduction by architomy in winter, from October to March. The posterior part of the abdomen undergoes spontaneous fission into from 2 to 4 fragments and depending on their position, the fragments regenerate their anterior ends or both anterior and posterior ends. Regeneration in P. reniformis takes place via a combination of epimorphosis (replacement of missing parts by cell proliferation and the growth of new tissue) and morphallaxis (the remodelling of pre-existing structures without cell proliferation). The morphogenetic events during regenerative restoration include de novo formation of branchial crown, formation of thoracic segments and restoration of the posterior end. Asexual reproduction appears to play a crucial role for ...

Biologists have long sought to identify and explain patterns in the diverse array of marine life histories. The most famous speculation about such patterns is Gunnar Thorson's suggestion that species producing planktonic larvae are rarer at higher latitudes (Thorson's rule). Although some elements of Thorson's rule have proven incorrect, other elements remain untested. With a wealth of new life-history data, statistical approaches, and remote-sensing technology, new insights into marine reproduction can be generated. We gathered life-history data for more than 1,000 marine invertebrates and examined patterns in the prevalence of different life histories. Systematic patterns in marine life histories exist at a range of scales, some of which support Thorson, whereas others suggest previously unrecognized relationships between the marine environment and the life histories of marine invertebrates. Overall, marine life histories covary strongly with temperature and local ocean productivity, and different regions should be managed accordingly.