The genome sequence of the cut surfclam, Spisula subtruncata (da Costa, 1778).

We present a genome assembly from a specimen of Spisula subtruncata (the cut surfclam; Mollusca; Bivalvia; Venerida; Mactridae). The genome sequence is 930.8 megabases in span. Most of the assembly is scaffolded into 19 chromosomal pseudomolecules. The mitochondrial genome has also been assembled and is 19.64 kilobases in length.

The genome sequence of a segmented worm, Terebella lapidaria Linnaeus, 1767.

We present a genome assembly from an individual Terebella lapidaria (segmented worm; Annelida; Polychaeta; Terebellida; Terebellidae). The genome sequence spans 765.20 megabases. Most of the assembly is scaffolded into 16 chromosomal pseudomolecules. The mitochondrial genome has also been assembled and is 15.97 kilobases in length.

A new species of Micromaldane (Polychaeta: Maldanidae) from the Falkland Islands, southwestern Atlantic, with notes on reproduction.

Micromaldane shackletoni n. sp. is described from the Falkland Islands in the southwest Atlantic. It is only the eighth species of Micromaldane to be recognized worldwide and is a new record of the genus for the Falkland Islands. The main characters of the new species are: up to 23 chaetigerous segments; nuchal organs as rounded ciliated pits with small central grooves anteriorly; two kinds ofnotochaetae: lancet-shaped chaetae and fine capillaries; neurochaetae as a single row of strongly curved, avicular uncini; a single pre-anal achaetigerous segment and anal plaque funnel-shaped with a crenated edge. This new species is a simultaneous hermaphrodite, only the second report of this reproductive mode in the genus along with Micromaldane androgyne Rouse, 1990. The stages of larval development from internal gametes to external in-tube development are also discussed.

The genome sequence of the segmented worm, Sthenelais limicola (Ehlers, 1864).

We present a genome assembly from an individual Sthenelais limicola (the segmented worm; Annelida; Polychaeta; Phyllodocida; Sigalionidae). The genome sequence is 1,131 megabases in span. Most of the assembly is scaffolded into nine chromosomal pseudomolecules. The mitochondrial genome has also been assembled and is 16.7 kilobases in length.

The genome sequence of the turban top shell, Gibbula magus (Linnaeus, 1758).

We present a genome assembly from an individual Gibbula magus (the turban top shell; Mollusca; Gastropoda; Trochida; Trochidae). The genome sequence is 1,470 megabases in span. Most of the assembly is scaffolded into 18 chromosomal pseudomolecules. The mitochondrial genome has also been assembled and is 16.1 kilobases in length. Gene annotation of this assembly on Ensembl identified 41,167 protein coding genes.

The genome sequence of Gari tellinella (Lamarck, 1818), a sunset clam.

We present a genome assembly from an individual Gari tellinella (Mollusca; Bivalvia; Cardiida; Psammobiidae). The genome sequence is 1,598 megabases in span. The majority of the assembly (99.85%) is scaffolded into 19 chromosomal pseudomolecules. The complete mitochondrial genome was also assembled and is 18.5 kilobases in length.

The genome sequence of the scale worm, Lepidonotus clava (Montagu, 1808).

We present a genome assembly from an individual Lepidonotus clava (scale worm; Annelida; Polychaeta; Phyllodocida; Polynoidae). The genome sequence is 1,044 megabases in span. Most of the assembly is scaffolded into 18 chromosomal pseudomolecules. The mitochondrial genome has also been assembled and is 15.6 kilobases in length.

What is Pseudopotamilla reniformis (Sabellidae)? Comparisons of populations from Britain, Iceland and Canada with comments on Eudistylia and Schizobranchia.

A neotype of Amphitrite Müller (1771) is established and re-described, using material collected in 2001 from near the type locality on the southwest coast of Iceland. We examined material from Iceland, Nova Scotia and Newfoundland, identified as Pseudopotamilla reniformis, showing scissiparity and commonly found in aggregations within kelp holdfasts or amongst encrusting fauna. By contrast, scissiparity has not been seen in a population recorded as P. reniformis from Wales (broadcast spawning is presumed, Chughtai & Knight-Jones 1988), which bores into limestone and that the present analysis shows to belong to a different species from P. reniformis. Sabella oculata Krøyer (1856, Norway) is a junior synonym of P. reniformis. Sabella aspersa Krøyer (1856, Greenland) and Sabella saxicava (Quatrefages, 1866, France) are re-instated and re-described in Pseudopotamilla. Pseudopotamilla saxicava (= Potamilla ehlersi Gravier, 1906) has a widespread distribution from Britain to the Arabian Gulf, Pseudopotamilla aspersa is found in Greenland and the distribution of P. reniformis is reduced to Iceland, northern Norway, Nova Scotia and Newfoundland. The genera Eudistylia Bush and Schizobranchia Bush are discussed in relation to Pseudopotamilla.

Three new species of Dysponetus Levinsen, 1879 (Polychaeta: Chrysopetalidae) from the South Atlantic and Southern Ocean, with a re-description of Dysponetus bulbosus Hartmann-Schröder, 1982.

Three new species of Dysponetus (Polychaeta: Chrysopetalidae) are described from the South Atlantic and Southern Ocean: Dysponetus ovalisetosus n. sp. from the Falkland Islands, Dysponetus bricklei n. sp. from South Georgia and Dysponetus antarcticus n. sp. from Antarctica are all characterized by having notochaetae that are oval in cross-section in contrast to the D-shape described for seven of the other species of Dysponetus. Dysponetus antarcticus n. sp. is the most distinct due to the combination of both a ventral cirrus on segment 3 and four eyes. Formerly mis-identified as Dysponetus bulbosus Hartmann-Schröder, 1982, it was discovered while clarifying the contradictory descriptions of that species published by Hartmann-Schröder in 1982 and 1986. Dysponetus bulbosus is re-described and newly figured. Dysponetus bricklei n. sp. and Dysponetus ovalisetosus n. sp. can be determined by comparing several characters including position of the median antenna, shape of the palps and cirri, and the number and shape of both the noto- and neurochaetae.

Intertidal and nearshore Nereididae (Annelida) of the Falkland Islands, southwestern Atlantic, including a new species of Gymnonereis.

The intertidal and nearshore Nereididae of the Falkland Islands are detailed and a new species of Gymnonereis described. The new species, Gymnonereis tenera sp. n., is the first record of the genus for the Falkland Islands. It is, so far, only known from a few intertidal locations in fine and muddy sands. Main distinguishing characters are: jaw teeth absent (in adults), 3 papillae in Area V-VI, falcigers absent, second ventral cirrus present throughout. Nereis atlantica McIntosh, 1885, known only from the description of a single specimen and one doubtful record from the Falkland Islands, is reviewed and transferred to Perinereis on the basis of the presence of shield-shaped bars in Area VI of the proboscis and the absence of notopodial falcigers. A key to all seven species discussed is provided.

Shallow marine benthic invertebrates of the Seychelles Plateau: high diversity in a tropical oligotrophic environment.

Soft sedimentary biotopes are extensive in the shallow Western Indian Ocean, especially on the Seychelles Plateau and Mascarene Ridge, yet pro rata compared with coral reefs the research effort devoted to them has been minimal. In this study we examine the benthic mollusc and polychaete worm assemblages of the shallow waters (11-62 m) around Mahe, in the Seychelles, and make direct comparisons with the temperate Irish Sea area and subtropical waters of Hong Kong, China (using identical methodology). Two assemblages were recognized, characterized by depth and sediment type. Of these, assemblage A (in shallow carbonate sands) was the most diverse, with diversity and richness measures exceeding those from the Irish Sea or Hong Kong. Hong Kong generally had the poorest fauna. Considering the Bivalvia alone, estimates of taxonomic distinctness showed this to be least for Seychelles assemblage A. The degree of conformity of the results to the concept of the latitudinal gradient in species richness and the possible underlying causes are discussed. Comparisons with other data suggest that the Seychelles support a benthic fauna at least as diverse as any other described from the tropics. A tentative examination of total bivalve species richness suggests a total of 400-500 for the Seychelles. This is in keeping with other Indian Ocean localities, but higher than known figures for continental east Africa. The findings of this paper support the case for widespread ecological and taxonomic studies of the Western Indian Ocean benthic invertebrates.