A new Scyllaeidae of the genus Notobryon is described from Guadeloupe, in the Lesser Antilles. Notobryon caribbaeus sp. nov. is characterized by having the anterior pair of body lobes remarkably bigger than the posterior pair, a stomach with eight triangular plates, a black and very wide ampulla, a lemon-shaped bursa copulatrix and a complex and well-differentiated sponge-like prostate. The first Caribbean records of Notobryon were provisionally assigned to the Australian species Notobryon cf. wardi and later transferred to Notobryon panamica. However, the structure of the male genital system is one of the main morphological characters to discriminate species in the genus and the presence of a prostate in N. caribbaeus sp. nov. distinguishes it from N. panamica, which remains confined to the eastern Pacific. Of the remaining four species in the world, only Notobryon bijecurum shares this character, but its external anatomy is different: it lacks a bursa copulatrix and the deferent duct is much shorter. Notobryon caribbaeus sp. nov. was captured in the context of an intensive expedition (‘Karubenthos’) organized by the Muséum National d'Histoire Naturelle, Paris and its description raises the total inventory of sea slugs in Guadeloupe to 150.

Analysis of mitochondrial (16S) and nuclear (H3) gene data using phylogenetic and population genetic approaches has revealed some genetic differences between two putative species of western Atlantic Dondice opisthobranchs that feed differentially on hydroids or on up-side-down jellies of the genus Cassiopeia. These results partially support the validity of the species Dondice parguerensis, which was described for the jelly-eating Dondice. However, phylogenetic analyses revealed that the hydroid-feeding species Dondice occidentalis and D. parguerensis are not reciprocally monophyletic and they are identical for the nuclear H3 gene. Although there are morphological and developmental differences between these two nominal species, the molecular data are inconclusive. A possible explanation is that the two putative species are in the process of speciation due to different feeding habits, resulting in the presence of genetic synapomorphies in D. parguerensis, but only in the more variable 16S gene. Because the ranges D. occidentalis and D. parguerensis overlap and there are no obvious barriers to gene flow between the two putative species, this may constitute a possible example of incipient sympatric speciation in benthic marine organisms.

The nudibranch Thordisa villosa is recorded for the first time from the west coast of India. It is the third known record of this species from India, observed after a long gap of 60 years. The last known record of this species from India was by Satyamurti (1952), from the Gulf of Mannar on the south-east coast. Specimens were collected in the intertidal rocky shores of Maharashtra and Gujarat. The occurrence of the species at three study sites confirms its range in this part of the Indian coastline.

Polycera hedgpethi and Godiva quadricolor are two species of nudibranchs widely spread along the Indo-Pacific by shipping. The first of these two species was originally described from Californian coasts, while the second was described from temperate South African coasts. Records of both species outside the Indo-Pacific are scarce, but have already been recorded in the Mediterranean (Gulf of Naples and Adriatic, Italy; French coasts). Moreover, G. quadricolor in the Mediterranean has been misidentified and its significance misinterpreted. In this paper, we provide new records of a significant number of specimens of both species from the region of Agadir (Morocco, Atlantic), as well as that of an additional specimen of G. quadricolor from the Bay of Algeciras (Strait of Gibraltar). This last species is recorded for the first time for the Moroccan and Spanish fauna and P. hedgpethi is also new for the Moroccan fauna. The shipping activities carried out in the areas where the specimens reported in this paper have been collected, as well as their habitual eutrophic conditions, lead us to the expectation of the settlement in the near future, if not yet, of well-established populations of both species.

New findings of opisthobranch gastropods are reported to the Azores resulting from fieldwork undertaken in the islands of Faial and São Jorge (Central Group, Azores) during August 2007. Intertidal and subtidal areas down to 35 metres deep were sampled. Forty-four species were collected and eight are new records to the Azores, namely Chelidonura africana, Odontoglaja sabadiega, Aplysia juliana, Elysia flava, Thuridilla picta, Doris sticta, Catriona maua and Taringa armata. This increases the diversity of opisthobranchs in the archipelago to 141 species. Our results provide further support for the closer affinity of the Azorean marine diversity with the eastern Atlantic/Mediterranean Sea biota (75% of species) but they also show a biogeographic bound with the Caribbean province (25% of common species).