Enhydrosoma curvirostre is redescribed from archived and new material with particular attention to the structure of the mouthparts and other details of the fine structure not previously reported. It is shown that the species cannot be maintained in Enhydrosoma but is more closely related to Cletodes, the genus in which the original author placed it. However, it is shown that the species must be assigned to a new genus, Spinapecruris, as a result of possessing autapomorphies on the maxillule (only seven setae on the basis), thoracopods 2–4 (a large spine on the distal margin) and possibly the caudal ramus (proximal insertion of seta VII) and lacking apomorphies which may define Cletodes.

Octomagelona bizkaiensis (Annelida: Polychaeta), a new genus and species of the family Magelonidae is described from the north-eastern Atlantic. The specimens were collected from the Capbreton Canyon, Bay of Biscay, at a depth of 1000–1040 m. The new genus and species differs from all known genera and species of the family Magelonidae by the presence of eight instead of nine thoracic chaetigers.

Polychaete worms obtained by RRS ‘Discovery’ from 200 to 4850 m north-west of Africa in 1979 contained 24 species of which five: Macellicephala violacea, Bathyeliosona abyssicola, Laetmonice filicornis, Maldanella harai and Potamilla torelli were present in the abyssal zone (>2000 m). Macellicephala violacea is widely distributed in the Arctic and the present record is the southern-most record of this species. Fifteen species were recorded from the bathyal zone, many of which have a wide distribution in the oceans. A Neopolynoe species from the bathyal zone is new to science.

Mats of articulated coralline algal turf are common on many rocky intertidal shores. The dense fronds provide a habitat for extremely diverse and abundant macrofaunal assemblages. Despite a large contribution to faunal biodiversity of rocky shores, little has been published about these assemblages. This study describes patterns of distribution and abundance of macrofauna in coralline turf on rocky shores around Sydney. In addition, the potential of environmental variables (sediment, epiphytes, length and density of coralline fronds) for determining these patterns was also investigated. Relatively consistent differences were found between macrofauna in low- and mid-shore areas at all times of sampling and on all shores. Although there was some variation among shores, there was generally significant variation in macrofauna between sites separated by tens of metres. Generally, a relatively small number of taxa were responsible for the great majority of dissimilarity between assemblages. Apart for the small bivalve Lasaea australis, however, these taxa varied between heights on the shore, among times of sampling and among shores. These data illustrate the important contribution that coralline turf has for biodiversity of faunal assemblages on rocky shores around Sydney. They also provide a basis for investigating biological processes and physical factors responsible for structuring patterns of biodiversity of macrofaunal assemblage in coralline turf.

The coexistence of three taxa of Codium (Chlorophyta: Codiaceae) was examined on wave-swept shores of western Ireland: the introduced macroalgae Codium fragile ssp. atlanticum and ssp. tomentosoides and the native Codium tomentosum. In spring 1999 and 2000, four sites were monitored to evaluate whether past predictions regarding temporal changes and species replacement occurred. Introduced and native species of dichotomously branching Codium occurred at four tidal levels: in tidepools in (i) the upper barnacle zone; (ii) the mid barnacle/fucoid zone; (iii) the mussel zone, and (iv) on emergent substrata in the red algal turf/kelp zone. Codium fragile ssp. atlanticum and ssp. tomentosoides grew together in 11·9% of surveyed pools containing Codium. Compared to 1971 censuses, C. fragile ssp. atlanticum had increased in relative abundance at all tidal levels, and the dominance of C. fragile ssp. tomentosoides had declined. The native C. tomentosum constituted the same percentage of the population as it did in 1971. Pool availability and primary rock surfaces were not limiting at most sites, indicating that inter-subspecific and inter-specific competition could not account for temporal changes in Codium distribution on Irish shores. Ecological constraints other than intra-generic competition may have contributed to the purported long-term changes in Codium abundance.

Freeliving marine nematodes were sampled on two occasions from an extensive grid of 20 stations in the Bohai Sea and its approaches. Differences within stations between sampling periods were small, resulting from small changes in abundance of dominant species. Differences between stations were significant, and were used to cluster stations into groups with similar species composition. These station groupings revealed a weak faunal gradient leading from the mouth of the Huanghe (Yellow River) to the Bohai Strait. Analyses relating faunal composition to environmental variables showed that there were significant differences in environmental variables between faunally-defined groups of stations. The variables most closely correlated with community structure were silt/clay and sand, depth, phaeopigment concentrations below the sediment surface, organic content and arsenic. These reflect natural processes within the Bohai Sea. A suite of univariate measures were related to distance from the river mouth, with a major discontinuity about 120 km into the Bohai Sea. Comparison of values of the biodiversity measures average taxonomic distinctness (Δ+) and variation in taxonomic distinctness (Λ+) suggest that the meiobenthos of the Bohai Sea as a whole is not under major pollution stress.

A new species Spiochaetopterus nonatoi is described from the south-eastern coast of Brazil, the type locality being Flamengo Bight, 6-m depth (23°30′S 45°06′W). This species is distinguishable from already erected species of the same genus by the following characteristics: oculate specimens of large size; maximum segments, 197 (N=15); maximum tube length, 45 cm; maximum body length, 20 cm; orange coloration of the fore part (peristomium and segment 1) and of the ventral shield on segments 6–7; shape of the specialized enlarged cutting seta on A4 with an obliquely truncated distal end; this slightly concave section is heart-shaped and clearly asymmetrical; segments B1 and B2 with one lobe on the neuropodia. This additional description in the genus Spiochaetopterus confirms the limited geographical area of each species in this genus. In spite of the probable ability of planktonic larvae of Spiochaetopterus to disseminate throughout the Atlantic Ocean, the benthic adults of each species cover only a limited geographical area. In particular, the stem species S. costarum loses its cosmopolitan character.

This paper presents results on the distribution, abundance, and size of Lophelia pertusa coral reefs in mid-Norway (62°30&;–65°30&;N) as compiled from own investigations, earlier scientific reports, reports from fishery surveys and fishermen. Detailed bathymetrical mapping covering an area of ∼600 km2 along the Halten gas-pipeline, and two nearby areas across the shelf revealed 70 Lophelia reefs. In general, the reefs occurred close to breaks and escarpments. High densities of up to nine reefs per km2 were found in areas with a rugged seabed topography and with a slope >0·6°. These seabed features have probably positive influence on the transport and concentration of food particles and thus control the local distribution of Lophelia. The area covered by individual reefs varied between 1230 m2 and 37,310 m2 with a mean of 5628 m2. The height of the reefs was positively correlated with the area. Reefs <10,000 m2 had a circular outline, while larger reefs were elongate, aligned parallel to the depth contours. Along the pipeline the average density of Lophelia reefs was 0·09 km−2 which indicates that the total number of reefs is ∼6300, covering ∼35 km2 within the whole study area.

Several new symbiotic associations involving Syllidae (Annelida: Polychaeta) are reported. The number of known host sponge species infested by Haplosyllis spongicola is updated to 36, with seven hosts being reported for the first time (i.e. Aplysina corrugata, Aplysina sp., Cliona sp., Cliona viridis, Phorbas tenacior, one sponge from Iran, one sponge from Cambodia). Two infestation patterns (a few worms per host cm3 in temperate waters and 10s or 100s in tropical waters) are identified. The taxonomic and ecological characteristics of the species are discussed. Five associations occurring between four syllid worms and decapod crustaceans are fully reported for the first time. Syllis cf. armillaris, S.ferrani and S.pontxioi occurred inside gastropod shells occupied by hermit crabs as well as Pionosyllis magnifica, which was also found inside the branchial chambers of the giant crab Paralithodes camtschatica. The description of Pionosyllis magnifica is emended on the basis of the new specimens found, while some taxonomic remarks on Syllis cf. armillaris are given. In addition, further evidence of sexual (P.magnifica) and asexual (S. cf. armillaris) reproduction in symbiotic syllids is provided.

A new species of Cerapopsis (Cerapopsis takamado) is described from the Atlantic coast of Morocco. The genus Cerapopsis, synonymized with Photis Kröyer for nearly a quarter of a century is re-established and now known to contain two species.

Terebellomorpha is a clade of predominantly tube-dwelling polychaetes, some of whose species are very abundant and whose habitats range from shallow to very deep waters. The group contains five families (Terebellidae, Ampharetidae, Pectinariidae, Trichobranchidae and Alvinellidae). This study of their inter-relationships uses DNA sequence data from five gene segments. Including outgroups, sequences were available for 15 species for 15 U2 snRNA, 14 for Histone H3, 23 for the D1 expansion region of 28S rDNA, 15 for the D9-10 region of 28S rDNA and 17 for subunit I of cytochrome oxidase. Outgroups included representatives of the polychaete families Cirratulidae, Sabellidae and Siboglinidae, and the clitellate Lumbricus. These sequences include eight GenBank entries for 28S D1 and one for CO1.

Generally, and in all analyses restricted to the data collected in this laboratory, but including all of these, Terebellomorpha is monophyletic. Within Terebellomorpha, the single maximum parsimony tree indicates that Alvinellidae (all data from GenBank) belongs to a clade with Terebellidae and some Trichobranchidae, contradicting morphological expectations. Terebellidae is paraphyletic with respect to Trichobranchus, this being associated with the subfamily Thelepodinae. The second trichobranchid genus Terebellides (for which only 28S D1 data is available from GenBank) is topologically very distinct to Trichobranchus. Additional data are needed to establish the family's monophyly. Also within Terebellidae, subfamily Terebellinae is paraphyletic with respect to Polycirrinae, supporting the suggestion that this subfamily's morphological simplicity is derived.

Two developmental stages of the micromorph rhynchonellid Tethyrhynchia mediterranea (Brachiopoda: Tethyrhychiidae) are described using scanning electron microscopy (SEM). They were found in niches of the mantle cavity of adult females, as T. mediterranea broods its offspring between the protecting valves of the shell. The developmental stages of T. mediterranea are very small (∼120 μm), but relative to adult body size of up to 1·2 mm in length they are larger than any other lecithotrophic brachiopod larva. Dispersal ability and phylogeography of T. mediterranea in the Mediterranean Sea is discussed.

Scanning microscope investigations were carried out on mandibles, labrum and paragnaths of several species of Mysidacea and Euphausiacea. Gut content analyses were in agreement with morphological observations. It appears that the morphology of the peri-oral structures and especially of the mandibles reflect the feeding habits, and that the well known relationships between the size of the molar process and the incisor one, i.e. a large molar process is associated with herbivorous feeding, is not always verified. Bacescomysis abyssalis and Bentheuphausia amblyops are believed to be mostly saprophagous, Boreomysis inermis and Meganyctiphanes norvegica are mostly phytophagous, Hemimysis speluncola is omnivorous, while Siriella armata and Thysanopoda orientalis are carnivorous species.

A new species of the cold-temperate austral amphipod genus Carangolia (Gammaridea: Urothoidae) is described from bathyal depths of the Bay of Biscay (north-east Atlantic). It was occasionally sampled in the south-eastern part of the Bay with sledges towed over muddy bottoms between 522 and 924 m water depth. This depth range falls mainly below the mud-line where the proportion of organic carbon increases in response to the deposition of silts and/or clay sediment. Most specimens were sampled by the lower net of the sledges, indicating a close association with the bottom. Abundance was relatively low, ranging between 0·18 and 4·90 ind 100 m−2, latter recorded below 700 m depth. The unusual massive appearance of Carangolia mandibles and its preference for bathyal foraminiferal oozes suggest that it is a specialized foraminifer consumer. The antitropical distribution pattern currently displayed by the genus could be an artefact due to equatorial submergence.

Twenty-seven species of Lumbrineridae are characterized; six are described as new: Lumbrinerides uebelackerae sp. nov., Lumbrineris perkinsi sp. nov., L. salazari sp. nov., Ninoe vargasi sp. nov., N. wardae sp. nov. and Lysarete raquelae sp. nov. Twenty-one species from the Grand Caribbean region are recognized herein and characterized based upon type and non-type materials: Augeneria bidens, Eranno bilabiata comb. nov., Lumbrinerides crassicephala, L. dayi, L. jonesi, Lumbrineriopsis cf. paradoxa, Lumbrineris floridana, L. cf. latreilli, L. nonatoi, L. paucidentataNinoe nigripes, Scoletoma branchiata comb. nov., S. candida comb. nov., S. ernesti, S. robusta comb. nov., S. tenuis, S. estudinum comb. nov., S. treadwelli comb. nov., S. verrili, S. parvapedata comb. nov. and S. elongata comb. nov. A key to identify all lumbrinerid species recorded from the Grand Caribbean region is included.

Differentiation between two samples of the polychaete Perinereis cultrifera collected in a brackish-water habitat and in an adjacent marine site at Elba Island (Italy) was assessed by morphological (number of paragnaths on the zones of the pharynx) and genetic (allozymes) approaches. Mean number of paragnaths differed significantly in zones IIl, IIr, III and V by t-test (P<0·05). Multidimensional scaling performed on Manhattan distances separated the individuals in two groups with a narrow zone of juxtaposition. Electrophoretic analyses of 22 allozyme loci revealed high levels of both within- and between-sample genetic heterogeneity, with a large number of private alleles. A general deficit of heterozygotes accounted for deviations from the Hardy–Weinberg equilibrium. Nei's genetic distance (D=0·185±0·018) and the mean value of the coancestry coefficient (Θ=0·381± 0·123, P<0·001 by permutation test) indicated considerable genetic divergence between the two samples. We concluded that the two groups can be assigned to sibling species. The observed divergence between the two samples may results from absence of gene flow and subsequent microallopatric differentiation through genetic drift, or, assuming migration between populations of the two sites, the model of divergence with gene flow may be compatible with this system.

A new species of Chalinula (Haplosclerida: Chalinidae), C. saudiensis, is described from the coral reefs of the Red Sea off Jeddah. The new species is remarkable in its vivid blue colour and its bioactivity. Its description includes cytological features in transmission electron microscopy.

Larvae of Chthamalus malayensis (Cirripedia: Thoracica) from Hong Kong were cultured in the laboratory. Larval development includes six naupliar stages and a non-feeding cypris stage. Larvae reached the cypris stage in 20 d at ∼21°C compared to 14 d at ∼28°C. Morphological features including the cephalic shield, frontal horns, labrum, abdominal process, antennules, antennae and mandibles in all nauplius and cypris stages were described and illustrated using a combination of light microscopy and scanning electron microscopy. Attempts were made to compare morphological differences between the nauplii and cyprid of C. malayensis with those of other Chthamalus species including C. stellatus, C. montagui, C. dentatus, C. fragilis, C. dalli, C. antennatus, C. fissus and C. challengeri. The present description of the nauplii of C. malayensis is not in agreement with the previous description of this species.

A new species of Branchiomaldane was identified in a collection of polychaetes living in colonies of a stony coral. Branchiomaldane maryae sp. nov. differs from all other species of the genus by the presence of lensed eyes and 1–3 branchial filaments per parapodium. Comparisons between B. maryae sp. nov. and the other species of the genus are provided, together with some phylogenetic considerations on the position of the genus.

Fecundity and size at maturity of the European lobster Homarus gammarus (Crustacea: Decapoda) was estimated in four coastal regions of Ireland. Egg size increased with carapace length (CL) (egg size=0·9939×ln (CL)−3·0809). The size–fecundity relationship for all coasts combined was (fecundity=0·0044×CL3·1554).  Physiological maturity was assessed using ovary colour, ovary factor, ova size, abdomen width/CL ratio, cement gland activity and moult status as criteria. Size at 50% maturity varied from 92·5 to 96  mm depending on region. The size–maturity relationship for all coasts combined was (Maturity= 1/(1+exp(14·595−0·15598×CL))). Over 60% of lobsters in the commercial landings were under the size at 50% maturity.  Relative reproductive potential (RRP) of different size-classes was calculated from the size–fecundity and size–maturity models and the numbers by length in the landings. The modal RRP size-class was 98–100 mm. The commercial landings were dominated by the 86–92  mm size-classes.