A new species of calanoid copepod, Centropages uedai sp. nov., is described from the neritic waters of the northern Red Sea. This species is characterized by: (1) symmetry of a globular female genital double-somite that is ornamented with an anterior irregular group of spinules as well as transverse and dorsolateral rows of spinules on each side; (2) second exopodal segment of female leg 5 bearing a strong trough medial process serrated along the distal 4/5 of its posterior margin; (3) second exopodal segment of male right leg 5 serrated laterally along distal 1/5 of its medial process; (4) third exopodal segment of male right leg 5 with medial seta bifurcated at its tip and with hyaline ridge on both sides; and (5) second exopodal segment of male right leg 4 asymmetrical with undulating, thicker and longer lateral spine than left leg. The new species does not belong to any known species groups of the genus.

Advanced stages of Scyllarus phyllosoma larvae were collected by demersal trawling during fishery research surveys in the western Mediterranean Sea in 2003–2005. Nucleotide sequence analysis of the mitochondrial 16S rDNA gene allowed the final-stage phyllosoma of Scyllarus arctus to be identified among these larvae. Its morphology is described and illustrated. This constitutes the second complete description of a Scyllaridae phyllosoma with its specific identity being validated by molecular techniques (the first was S. pygmaeus). These results also solved a long lasting taxonomic anomaly of several species assigned to the ancient genus Phyllosoma Leach, 1814. Detailed examination indicated that the final-stage phyllosoma of S. arctus shows closer affinities with the American scyllarid Scyllarus depressus or with the Australian Scyllarus sp. b (sensu Phillips et al., 1981) than to its sympatric species S. pygmaeus.

A new species of Admete Møller, 1842 (Cancellariidae), A. clivicola is described from the upper continental slope off south-western Norway, and the species Admete contabulata Friele, 1879 is reinstated as a valid species. Iphinopsis inflata (Friele, 1879) is redescribed and a lectotype for the species is established. The taxonomic status and bathymetric distribution of the species of Admete and Iphinopsis in the Norwegian Sea are discussed.

A new species of the genus Onchidoris is described from the south-western Atlantic, on the coast of Brazil, in the States of Rio de Janeiro and São Paulo. To date, the genus Onchidoris is known almost exclusively from the northern hemisphere, especially the Atlantic coast of Europe and the Mediterranean Sea. The single previous record from the southern hemisphere is Onchidoris maugeansis, described from Australia. This is the first record of the family Onchidorididae from the coast of Brazil. Onchidoris brasiliensis sp. nov. is very similar to Onchidoris depressa, from England and the northern coast of Spain, but is distinguished by the presence of a triangular protuberance on the edge of the inner lateral radular tooth and a wide closed branchial circle with tubercles inside. Furthermore, the egg mass of O. brasiliensis sp. nov. contains a single row of eggs, whereas that of O. depressa has multiple rows. Onchidoris brasiliensis sp. nov. has lecithotrophic development, the first record of this type of development in the genus. There is a relationship between O. brasiliensis sp. nov. and the bryozoan Parasmittina protecta.

Despite the increasing number of reports on the deep-sea molluscs from the south-western Atlantic, we know very little about the protobranchs. The lack of information on the protobranch Pelecypoda off southern Brazil is reflected in the genus Yoldiella. This contribution is part of an effort to increase the knowledge about this group off the Brazilian coast. Eight species of Yoldiella are recognized here. For Yoldiella biguttata, previously reported from Brazil, the known distribution is extended southwards to the Campos Basin. For Yoldiella similis this is the first record in the western Atlantic Ocean. For Yoldiella extensa and Yoldiella aff. jeffreysi this is the first record for Brazil. Four previously unknown species are described, Yoldiella lapernoi sp. nov., Yoldiella paranapuaensis sp. nov., Yoldiella arariboia sp. nov. and Yoldiella curupira sp. nov. Considering only conchological features for the Atlantic species we could propose some clusters of species of Yoldiella.

Specimens of Conus jaspideus Gmelin, 1791 collected along the Brazilian coast were dissected for morphological studies of the soft parts and radula, in a recharacterization of the species. Two specimens collected in the State of Bahia, proved to be imposex. Specimens in an aquarium were photographed during the process of predation. Herein, for the first time, the atrophied penis of an imposex specimen of C. jaspideus is illustrated, as well as the feeding process, contributing to the knowledge of the family.

Eumetula vitrea, a new species of Cerithiopsidae, is described from the upper continental slope outside western Norway. The taxonomic status of the Eumetula species complex is discussed. While Eumetula arctica is a shelf species rarely found in sub-zero waters, E. vitrea is one of a group of species supposedly found only in negative temperature or water fluctuating between negative and positive temperatures (below ~570 m) in the bathyal around the Norwegian Sea.

A sample of 360 Bathypolypus sponsalis from the central western Mediterranean Sea (the Sardinian Channel and the Tyrrhenian Sea) was analysed in order to describe size, depth distribution and reproductive data. The first record of the species in the Tyrrhenian Sea and of a spent female are reported in this paper. The size-structure of the sample was in between values of documented data from the western and eastern Mediterranean basins and the minimum mature sizes in both sexes and spermatophore length were similar to previous data from the eastern Mediterranean Sea. Low values of gonadosomatic index and fecundity, the asynchronous ovulation, in addition to an extended reproductive period, have been associated with an intermittent spawning strategy.

A new species of appendicularian, Fritillaria ragusina, is described from specimens collected between the surface and 300 m depth at three stations in the open south Adriatic Sea (north-eastern Mediterranean). Fritillaria ragusina is characterized by a broad trunk–tail connection created by a wide tail fin in the initial part of the tail, sloping shoulders of the tail fin, broad tail musculature, multiple fusiform amphichordal cells along the edge of the tail musculature and small size at sexual maturity (maximum recorded trunk length of 445 µm and maximum recorded tail length of 960 µm). Maximum abundance, 2.4 ind m−3, was found within the 0–50 m layer.

Two new species of zoarcid fish, Ophthalmolycus eastmani sp. nov., and Ophthalmolycus polylepis sp. nov. are described from specimens collected from the Bellingshausen Sea and Gerlache Strait, Southern Ocean, at depths of 1837 and 1056 m. Ophthalmolycus eastmani can be distinguished from its congeners by the following combination of characters: two posterior nasal pores; epidermal prickles on lips and snout; gill slit extending ventrally to the lower margin of the pectoral fin base; vertebrae asymmetrical 26 − 27 + 91 − 92 = 117 − 118; dorsal fin rays 111–113; dorsal fin origin associated with vertebra 6, with no free pterygiophores; pectoral fin rays 17–18; two postorbital pores; lateral line with ventral and mediolateral branches; scales extending anteriorly to just anterior to the anal fin origin; six branchiostegal rays; oral valve nearly reaching the anterior edge of vomer; palatine teeth in two rows anteriorly; 3–5 pseudobranch filaments; two well developed pyloric caeca; pelvic fin and vomerine teeth present. Ophthalmolycus polylepis can be distinguished from its congeners by the following combination of characters: two posterior nasal pores; epidermal prickles on lips; gill slit extending ventrally just to below mid-pectoral fin base; interorbital pore present; two postorbital pores; lateral line triple with ventral, mediolateral and dorsolateral branches; scales extending anteriorly to predorsal area, abdomen, pelvic fins base, and pectoral fins base and axil; vertebrae asymmetrical 22 + 76; dorsal fin origin associated with vertebra 5; pectoral fin rays 18; six branchiostegal rays; oral valve overlapping the anterior edge of vomer; two rows of palatine teeth anteriorly; two vestigial pyloric caeca and 2 pseudobranch filaments; pelvic fin and vomerine teeth present. A key to the species of Ophthalmolycus is provided.