Lionfishes are conspicuous and disruptive predators once introduced outside of their native range. Here we provide a revision of the occurrences of the common lionfish Pterois miles (Bennett, 1828) in the Mediterranean Sea, showing its rapid geographical expansion since 2012. A single lionfish was photographed in September 2016 during a scientific survey off the Vendicari coast, Southern Sicily, Italy. This is the first record of this notorious invasive species from Italian waters. Given its large size, conspicuous appearance, and venomous spines, it is critical to involve informed citizen scientists in tracking the spread of this species and to develop means to manage or adapt to its presence in the Mediterranean Basin.

Devil firefish Pterois miles (Bennett, 1828) is a species native to the Indo-Pacific that along with Pterois volitans (Linneaus, 1758) has been invading the western Atlantic since the 1980’s. Morphological characters, life cycle, habits, and dispersal potential of this species are very similar to those of Pterois volitans, to such extent that its taxonomic classification remains controversial. For example, the USGS database lists two species (Pterois volitans/miles) as a single one. Therefore, the probability of both species having been captured and confused is high because their identification by meristics and morpho¬metrics is problematic. As a part of our investigation in genetic connectivity of invasive lionfish, we collected 77 specimens from Chinchorro Bank, Mexico. Identifying the samples by analysis of partial mtDNA cyt b sequences, we found that one sample corresponded to Pterois miles. The sequence of this specimen had 100% similarity to the sequence of Pterois miles specimens collected off the coast of North Carolina in 2004. This indicates that the species has extended its distribution into the Caribbean basin, but its current geographical distribution is unknown. Our results show that the presence of Pterois miles in the Caribbean appears low, approximately 1.3% of that of Pterois volitans. This study reveals the progress of the invasion of Pterois miles in the Caribbean and advocates for genetically confirmed identification and management of Pterois species.

The doctorfish Acanthurus chirurgus (Bloch, 1787) is reported for the first time from the central Mediterranean, based on a specimen caught in Maltese waters during August 2016. Since the only previous Mediterranean record of this species was based on a single individual observed in the Tyrrhenian Sea, the present record likely represents an independent introduction that may have occurred through the aquarium trade or via shipping. Two other surgeonfish species, Acanthurus coeruleus Bloch and Schneider, 1801 and Acanthurus monroviae Steindachner, 1876, were previously recorded from the central Mediterranean. While A. coeruleus may have established a population in the Levantine Sea, like A. chirurgus it has only been reported once from Malta (and from the central Mediterranean in general); both A. coeruleus and A. chirurgus are, therefore, considered to be casual species in Maltese waters. In contrast, A. monroviae was reported from several Mediterranean countries including Tunisia and Malta in the central Mediterranean. Here we present several authenticated reports of this species from Maltese waters, which strongly suggest that it has managed to establish a population in this region, although the possibility of multiple introductions cannot be excluded.

Since 1989, specimens of the non-native mud sleeper Butis koilomatodon (Bleeker, 1849) (Perciformes: Eleotridae) have been collected off of the Brazilian coastline. The species has the potential to invade marine and estuarine systems, and outcompete native fish. The present study reports an additional occurrence of B. koilomatodon in the intertidal zone of Maranhão state, eastern Amazon coastal region of northeastern Brazil. Detailed environmental data was obtained at the site of specimen collection, and B. koilomatodon behavior in situ was documented. Ten individuals were sampled from three different mediolittoral tide pools at Panaquatira beach. Predominant substrate, percentage of algae coverage, surface area, tide pool volume and depth, roughness, pH, salinity, water temperature and dissolved oxygen were also documented. Ecological plasticity of analyzed individuals, associated with port handling behavior in neighboring bays of the studied area, suggest that the B. koilomatodon route of introduction was ship-mediated. High shipping intensity in this region may have favored introduction and possible invasive process of the species nearshore due to satisfactory propagule pressure. Nevertheless, more data are needed to comprehend the invasive potential of B. koilomatodon in Brazilian waters.

The occurrence of the white-spotted Australian jellyfish Phyllorhiza punctata Lendenfeld, 1884, an Indo-Pacific scyphozoan species mainly restricted to the Levantine Basin, is hereby reported for the first time from Maltese waters (western Mediterranean) and from the Ionian coast of Italy. Considerations on possible vectors of introduction of the jellyfish species to this part of the Mediterranean are made.

Two conspicuously-colored facelinid nudibranchs, wide spread in the Indo-West Pacific Ocean, were recently sighted off the Israeli Mediterranean coastline. We report the occurrence of Phidiana militaris (Alder and Hancock, 1864) off a sunken submarine in Haifa Bay – the first record of the species in the Mediterranean Sea. A recent sighting of Caloria indica (Bergh, 1896) off northern Israel, previously known from two individuals recorded in the late 1980s, may indicate a separate introduction or the spread of a cryptic, local, self-propagating population.

The ragged sea hare Bursatella leachii Blainville, 1817 is a circumtropical mollusc species widely distributed both in the Atlantic and the Indo-Pacific, including the Red Sea. Since the mid-20th century, it has been moving east to west in the Mediterranean Sea. The present work reviews the spread of B. leachii in the Mediterranean Basin and provides the first record in the Mediterranean Morocco (Marchica coastal lagoon), the 19th country colonized by this taxon out of 23 with Mediterranean Sea coastlines. This study also constitutes the first record from the southern Alboran Sea and represents the westernmost record of the species in the Mediterranean. Although the Red Sea is thought to be the most likely origin (Lessepsian migration) of the Mediterranean populations, phylogenetic and phylogeographic studies would be desirable to assess with certainties both the taxonomy and the proper origin of the species not only in the western part of the basin, but also in the Mediterranean Sea as a whole.

This study reports the first record of the Indo-West Pacific nudibranch Dendronotus orientalis (Baba, 1932) in the Northeastern Pacific Ocean. A reproducing population was discovered in fouling communities on floating docks in South San Francisco Bay, California, in March 2016. Dendronotus orientalis joins a large number of introduced marine invertebrates that have taken up residence in San Francisco Bay.

The invasive sabellid polychaete Branchiomma bairdi McIntosh, 1885 was collected in the Boughrara Lagoon (southern Tunisian coast) between 2012 and 2013. This species was originally described from Bermuda and has been widely reported in the Caribbean Sea. It has been considered as non-indigenous species on the Pacific coast of Panama and the California Gulf. Recently, B. bairdi was recorded along the Italian and Turkish coasts, Australia, Canary and Madeira Islands. It was suggested that the commercial shipping is the most likely vector for the introduction of the species to Mediterranean Sea. A description of the species along with a discussion of its systematic position and ecology are provided.

The non-indigenous crabs Percnon gibbesi (H. Milne Edwards, 1853) and Callinectes sapidus (Rathbun, 1896) (Crustacea, Decapoda, Portunidae) are reported from Genoa and La Spezia, respectively, in the Ligurian Sea at the northern rim of the Mediterranean Sea. Both specimens were collected by fishermen who then brought them to the attention of professional scientists. This illustrates the importance of engaging local communities in detecting non-indigenous species and monitoring their spread.

The occurrence of the red swamp crayfish Procambarus clarkii is documented in the surroundings of Lake Varano (Puglia region, SE Italy), testifying to the ongoing diffusion of this invasive crayfish in north-eastern Puglia, an area characterised by an extensive network of natural and artificial watercourses. In addition, the species is recorded for the first time in the Salento Peninsula, in the south-western part of the region. The hydrology of the area is dominated by karstic phenomena, and the ecological consequences of the colonization of hypogean environments by P. clarkii are discussed. These records, in conjunction with a number of recent observations made in Puglia and in other regions of southern Italy including Sicily and Sardinia, indicate that the species is far more widespread in the area than previous studies have suggested.

The Great Lakes watershed is one of the most invaded freshwater ecosystems, making early and rapid detection of new invaders critical to reduce their effects on this fragile system. The genus Corbicula, freshwater clams native to the temperate/tropical regions of Asia, Africa, and Australia, contains some of the most common and successful aquatic nuisance species in the New World. These invasive populations appear to exclusively comprise asexual clonal lineages, which hinder our taxonomic understanding. Previous work suggests three clonal morphotypes have invaded the New World—Forms A, B, and C, with Forms A and B co-occurring in North America. Here, we report on an apparently novel North American invasive Corbicula lineage recently discovered in the Illinois River, which has an artificial connection to the Great Lakes. This putative new morph was found co-occurring with previously described Corbicula morphotypes. Our main objective was to document the occurrence of this new morphotype (=Form D) and perform a preliminary analysis of its distinctiveness from sympatric Forms A and B using shell phenotype characteristics and mitochondrial (mt) and nuclear DNA markers. Results showed that the three co-occurring forms were distinguishable using shell phenotype and nuclear 28S ribosomal DNA sequences. Individuals were unambiguously assigned to one of three discrete shell phenotypes, Form A, B, or D, with Form D specimens characterized by fine rust colored rays and white nacre with purple teeth. Likewise, 28S genotypes identified three distinct morphs, with Form D differing from Forms A and B by 2–6 base pairs. In contrast, Form D individuals were distinguishable from Form B via mitochondrial markers but shared an identical mtDNA haplotype with sympatric Form A individuals. This latter result could stem from androgenetic capture of Form A eggs by invasive Form D sperm, a rare form of inheritance previously inferred for co-occurring North American Corbicula clones. Further morphological, ecological, and genomic analyses characterizing the three morphotypes are required to establish the significance of our preliminary findings.

This paper documents the arrival of the non-native bivalve Rangia cuneata in a shallow-water basin of Pärnu Bay, north-eastern Gulf of Riga, Baltic Sea, Estonia. The bivalve was collected for the first time in October 2016. The species occurred at low densities along a 25-km stretch of coastline. The size distribution suggests R. cuneata is established in the study area. This species represents the first obligatory suspension-feeding soft bottom bivalve in this low salinity area. Consequently, R. cuneata has a potential to intensify benthic-pelagic coupling as well as to improve the overall water quality of the bay. As Pärnu Bay is the northernmost location of the species’ geographic range, winter temperature likely controls the species survival and further spread in the region.

Urban ecosystems house artificial infrastructures such as ports, transport stations and commercial centres which are often introduction foci for exotic species. The connectivity of these structures to other centres specialised in commodity flows located in urban cores, enhances the accidental transport and spreading of exotic species which can become invasive. Despite this fact, targeted investigations to detect establishment of invasive species in tropical urban landscapes are lacking. A survey conducted on ant communities in 15 cities throughout Côte d’Ivoire (West Africa) allowed us to find the highly invasive tropical fire ant (TFA) Solenopsis geminata for the first time in the country. DNA analysis of mitochondrial cytochrome c oxidase I (COI) of two specimens of S. geminata found that they had a close genetic relationship with specimens from Venezuela. From the 15 towns surveyed throughout Côte d’Ivoire, this ant was discovered only in industrial areas of Abidjan near the port zone suggesting an early stage of invasion.