The red lionfish (Pterois volitans) was first recorded in Martinique on 1 February 2011. Three years later, despite control measures to prevent the increase of lionfish population densities, the species is now well established. Maximum density has reached 1320 individuals ha−1 in some locations and the maximum fish size of 41 cm total length has been observed. A monitoring program was initiated by the Marine Institute of Martinique (OMMM) in 2011 to monitor the invasion and adjust local control efforts. Our results highlight how fast lionfish have been able to invade new littoral areas, especially hard bottom habitats. It took two years for them to completely colonize the west coast of Martinique, despite increasing capture efforts. It is expected that small-scale fisheries would target lionfish. Coastal ecosystems are clearly being subjected to a new threat, which may negatively affect local biodiversity.

Leptodius affinis (De Haan, 1835), belonging to the family Xanthidae, is reported for the first time from Gujarat on the western coast of India. The identification of this species is difficult as it is very morphologically similar to another closely related species, Leptodius exaratus (H. Milne Edwards, 1834). Leptodius exaratus is commonly observed in the rocky intertidal areas of the western coast of India. The carapace characters of both species are very similar; however, the morphology of the first male gonopod is the most important and reliable feature for distinguishing these two species. Recent work on these species indicated that Leptodius exaratus could be found in the western Indian Ocean, the Persian Gulf and the Red Sea, whereas Leptodius affinis occurs in waters ranging from the eastern Indian Ocean to the central Pacific Ocean. The present study reports the occurrence of Leptodius affinis on the western side of the Indian Ocean.

Echinolittorina punctata was historically distributed in the southern sectors of the Mediterranean Sea. However, in the last decades a progressive range extension has occurred. In this context, new populations in France (Colliure, Cap d'Agde) and in Italy (Monte Argentario, Tuscany) are reported here. The population in Cap d'Agde is the northernmost in the entire Mediterranean Sea, the population in Monte Argentario is the northernmost along the Italian Tyrrhenian coastline and along the direction of range extension described in the last few years. Details on population density and size frequency distributions in Monte Argentario are provided, showing a decrease in density and an increase in minimum size from south to north. New records are also provided from Salamina Island and Rhodes Island in Greece. The latter likely dates back to 1836–1837 and is the first record from the Mediterranean Sea. This record confirms that the species was widely distributed in the Levantine Sea at the time, although records from Greece and Turkey are extremely rare in the literature and in museum collections.

The opisthobranch gastropod Hydatina physis (Linnaeus, 1758) is recorded from the north-west coast of India, off Veraval, Gujarat. A literature review on the distribution of this species revealed that this is the first report of H. physis from Indian waters since 1877 when a specimen collected from Chennai along the east coast of India and deposited in the Australian Museum was later identified to be H. physis. A note on the morphological features of this specimen is detailed in the present paper.

A new species of corallivorous goniasterid, Evoplosoma watlingi n. sp., from Bear Seamount in the North Atlantic is described in conjunction with an overview of other species within the genus Evoplosoma. Hippasteria tasmanica McKnight, 2006 is re-classified within Evoplosoma. In situ images of Atlantic deep-sea Goniasteridae, including Evoplosoma spp., Hippasteria phrygiana and Circeaster americanus, are presented herein. Observations of several Evoplosoma species and the Atlantic C. americanus are documented for the first time, recorded by the R/V Okeanos Explorer. The feeding duration of C. americanus is also documented for the first time.

The ceramiacean red alga Acrothamnion preissii is an Indo-Pacific species that was first recorded in the Mediterranean Sea (Italy) in 1969, and which subsequently spread within the north-western basin, reaching the Balearic Islands to the west and Sicily to the south. Here we record A. preissii from the Maltese Islands, which represents a further southwards expansion of its known distribution range in the Mediterranean Sea. Although this species can be invasive, becoming the dominant epiphyte by forming dense turfs that smother native species, so far there is no evidence for such an invasion phase in the Maltese Islands.

The occurrence of the Indo-Pacific porcupine puffer fish Diodon holocanthus (Linnaeus, 1758) was recorded on 17 November 2013 on the Gopalpur coast of the Ganjam district, Odisha, as the first distributional record of this species from the east coast of India. Recordings appeared to increase after the event of the super cyclone ‘Phailin’, which occurred during 12 October 2013. Since then, many incidents of bycatch were observed from the Gopalpur coast. This poisonous porcupine puffer posed a subsequent threat to local anglers by damaging their fishing nets and by reducing the catch of commercially important fishes. However, a lack of substantial information regarding this puffer from the Gopalpur coast makes it difficult to correlate the facts.

The presence of the fish species Enneapterygius pusillus and confirmation of Parablennius opercularis occurrence in the Kuwaiti waters of the northern Arabian Gulf regions are both reported here. One adult specimen of each species was photographed in the Qit at Binaya patch reef off Al Khiran, in southern Kuwait waters. The pixie triplefin record is a new ichthyofaunal record for the northern Arabian Gulf.

Specimens of the deep-sea scale worm Neopolynoe acanellae (Verrill, 1881) (Polychaeta, Polynoidae) were collected at depths between 466 and 1405 m in Canadian waters while still attached to their host, the pennatulacean coral (sea pen) Pennatula grandis Ehrenberg, 1834. The present records extend the northern latitude of occurrence of N. acanellae in North America by 17o (~2000 km) to include the northern continental shelf of Newfoundland and Labrador and the lower Arctic, off the southern coast of Baffin Island (Canada). Analysis of the worm's intestinal content confirmed the presence of sea pen soft tissues and sclerites, suggesting that this species feeds on its host and is therefore parasitic.

Little is known about elasmobranchs along the northern coast of South America. During five boat surveys in Suriname offshore waters we visually documented the presence and behaviour of the free-ranging whale shark Rhincodon typus and two mobulid rays: the giant manta ray Manta birostris and the Chilean devil ray Mobula tarapacana. Three sightings were made of R. typus at the surface in shallow coastal waters where the water depth measured 46–67 m. One of these sightings was confirmed by photographs. Manta birostris was positively identified on five occasions while at the surface, all in shallow waters of less than 57 m deep. Four additional sightings, not accompanied by photographs, were identified as Manta spp. One devil ray, photographed and identified as Mobula tarapacana, was recorded at the surface in deep waters (2491 m) in July 2012. These records of R. typus, Manta birostris and Mobula tarapacana are the first for Suriname and therefore add to the documented information of these species within the Wider Caribbean Region and contribute to the knowledge of the pelagic distribution of these species.

Annulobalcis aurisflamma is a parasitic mollusc of the crinoid Tropiometra carinata. It was originally described from São Paulo (south-eastern Brazil) and recently recorded from Bahia (north-eastern Brazil). In the present study, we report the presence of Annulobalcis aurisflamma on the coast of Alagoas (north-eastern Brazil), extending its known distribution to up to 400 km northward into the western Atlantic.

The first record of Lebetus guilleti for the Italian seas is reported here. The finding is based on photographic records of specimens located in shallow waters off the Conero Promontory (An) along the Adriatic coast of Italy. This record expands the distribution range of this species in the Mediterranean and moves its southern limit in the Adriatic Sea 170 km further south, adding to the suspicion that the distribution of this cryptic species might be wider than previously described. Recreational SCUBA diving focused on biodiversity observations and underwater photography proved instrumental again in providing information about the presence and distribution of marine fauna, including the most easily overlooked species.

Two specimens of Chromis notata (Pomacentridae) and one specimen of Sagamia geneionema (Gobiidae) were captured in Suttsu Bay, the Sea of Japan. These constitute the first records of the species from Hokkaido Island, northern Japan.

Albinism is a hereditary lack of pigmentation caused by deficiencies in enzymes related to the metabolism of melanin. This mutation is present in marine vertebrates and invertebrates, including the Holothuroidea class; nevertheless, information about the occurrence of albinism in these kinds of echinoderms is scarce and refers to species from temperate and cold regions of the ocean. In 2013, we observed two albino individuals of Isostichopus fuscus, one at Loreto (25°45′54″N, 111°14′36″W) and the second one at Los Angeles Bay (29°02′54″N, 113°29′49″W). This is the first documented record of albinism for this species.

The Chinese mitten crab Eriocheir sinensis H. Milne Edwards, 1853 is a native crab of East Asia. It is predominant in freshwater but migrates seawards to breed. It was found in Normandy, for the first time, in 1943 (Hoestlandt, 1943, 1948). Seventy-one years of observations along the Normandy coast and in the Seine estuary, as well as in the ship-canals and inner seaport of Le Havre, have recorded a total of 65 crabs at 33 locations. The observation of an E. sinensis juvenile in mussel beds along the Calvados coast indicates that this habitat can be a favourable location for larval settlement.

Morphological and molecular data on brittle stars from the Saint Peter and Saint Paul Archipelago, a very small isolated group of islets situated between South America and Africa, are hereby presented. We found no endemic ophiuroids. Instead, the five species, Amphipholis squamata, Ophiactis lymani, Ophiactis savignyi, Ophiocomella ophiactoides and Ophiothrix (Ophiothrix) angulata, are either cosmopolitan or derived from the equatorial western Atlantic region. Results indicated a western Atlantic colonization and highlighted the existence of cryptic species in the genus Ophiactis.

The north-west Pacific nemertean Cephalothrix simula has been introduced to the Pacific coast of North America, to the Mediterranean Sea and to the Atlantic coast of the Iberian Peninsula. This paper describes the first records of Cephalothrix simula from northern Europe, revealing a broader range for this non-endemic palaeonemertean species. A tree-based species delimitation method (Poisson Tree Process) employing the mitochondrial cox1 gene fragment reveals that four of five Cephalothrix specimens collected from The Netherlands correspond to Cephalothrix simula and only one to the endemic Cephalothrix rufifrons. The Cephalothrix simula sequences from The Netherlands exhibit the highest similarity with sequences from the native area and those from the invaded area in southern Europe. Its co-occurrence with the native Cephalothrix rufifrons in the same habitat is reported. External characters potentially distinguishing live Cephalothrix simula from Cephalothrix rufifrons are given. This finding raises the number of recorded species in The Netherlands to 20.

A recent stranding of a basking shark Cetorhinus maximus in north-western Bali represents the first confirmed record of this large, filter-feeding shark species in Indonesian waters. Based on measurements of the fins and claspers, the adult male specimen was estimated to be between 5.6 and 8.1 m LT, with an average estimate of 6.7 m LT. It is possible that the Indonesian Throughflow is an important route for this species during transequatorial migrations.

Here we report on the first finding of Nanozoanthidae (Anthozoa: Hexacorallia: Zoantharia) in the Red Sea and the first record west of Western Australia. A single specimen of Nanozoanthus sp. was found at a depth of 13 m off Dumsuq Island, the Farasan Islands, Saudi Arabia (16°33.846′N 42°03.510′E) during SCUBA surveys. Previous research had hypothesized that the genus could potentially be widespread in the Indo-Pacific and was simply undetected due to its small and cryptic nature, and the current specimen provides support for this idea. Such findings demonstrate the importance of biodiversity surveys by taxonomic specialists in understudied marine regions.

Sea cucumbers are important due to their rotation of key nutrients and high medicinal values. With this in mind and considering the lack of scientific knowledge about them, the purpose of this research was to identify the species of sea cucumber occurring in the intertidal habitats of Hengam Island. Field sampling and surveys were carried out along the coastline based on the geomorphic and habitat characteristics of eight sampling stations in the inter-tidal zone. The samples that were collected from the stations were transferred to the laboratory and identified using morphological keys and a review of their ossicles. By reviewing the literature on the distribution of sea cucumbers, it was determined that a new observation had been made of Holothuria arenicola and Holothuria bacilla from Hengam Island (Persian Gulf).