Since 2017, a sea anemone species has been registered in central Portugal with a morphology comparable to Phymactis papillosa, from the Pacific shore of south and central America. In this paper, we have collected two individuals from Cascais, Portugal, extracted their DNA and amplified and sequenced the internal transcribed spacers I and II, markers frequently used in Cnidaria barcoding. The sequences obtained were compared with the ones available on GenBank, using the Basic Local Alignment Search Tool (BLAST) on the NCBI website. This procedure allowed the identification of P. papillosa. This is the first confirmed record of P. papillosa in European coasts. Citizen science data suggest occurrences in the Alentejo coast (south-west Portugal) and Mediterranean coast around Murcia, although no genetic or morphological confirmations of these records have been made. The potential effects of this species introduction are discussed.

New in situ records of the sublittoral sea anemone Oulactis coliumensis (Riemann-Zürneck & Gallardo, 1990) are provided from different localities of northern Chile and Peru. Specimens were generally observed buried in shallow soft bottoms (3–25 m depth), near port cities and in areas with a high organic load. This is the first report of the species outside its type locality (off the Bay of Coliumo, Chile; ~36°S), extending its range of distribution to lower latitudes.

We describe and illustrate a new genus and species of sea anemone from the intertidal in the Gulf of California (Mexico). Tenactis gen. nov. is characterized by mesenteries decamerously arranged, a single pair of directives attached to a single and strong siphonoglyph, small conchula, endodermal marginal sphincter muscle, pedal disc with basilar muscles, cinclides in pedal disc and proximal column, column with verrucae and pseudoacrorhagi, and a cnidom with p-mastigophores A2 and p-mastigophores B1 and B2a. Tenactis riosmenai gen. et sp. nov. is characterized by having a column not divisible into regions with longitudinal rows of verrucae distally and pseudoacrorhagi forming spherical structures at the tip, only 10 pairs of perfect mesenteries, diffuse endodermal marginal sphincter muscle and p-mastigophores A2 and p-mastigophores B1 and B2a in the filaments. Because of the decamerous arrangement of the mesenteries Tenactis gen. nov. most closely resembles some members of Actiniidae, Haloclavidae, Minyadidae, Oractiidae and Limnactinidae (Actinioidea), Halcampidae (Metridioidea) and Halcuriidae (Actinernoidea). However, the combination of having a decamerous arrangement of mesenteries, single siphonoglyph, conchula and cinclides indicate this new genus belongs to Haloclavidae. Additionally, the presence of a diffuse endodermal marginal sphincter muscle, basilar muscles, a single pair of directives, column with longitudinal rows of verrucae distally and pseudoacrorhagi, p-mastigophores A2, and p-mastigophores B1 and B2a in the filaments distinguish Tenactis riosmenai gen. et sp. nov. within Haloclavidae. This is the first record of the family Haloclavidae for the Gulf of California.

A new species of tube-dwelling anemone of the genus Ceriantheopsis (Cnidaria: Ceriantharia), Ceriantheopsis lineata sp. nov., is described and can be found in fine sand or mud in the sublittoral zone (0–200 m) from Argentina to Brazil (Warm Temperate South-western Atlantic). This new species is distinguished from its congeners by a number of features, however some characters (directive tentacles, line on tentacles and length of P2) allow a conclusive identification among the other Ceriantheopsis species.

The occurrence of Cavernularia pusilla is reported for the first time from the Sea of Marmara, extending the range of the species in the eastern Mediterranean and providing the first report of the species from Turkish waters.

The Mediterranean endemic coral Maasella edwardsi (de Lacaze-Duthiers, 1888) is recorded for the first time from the Aegean Sea coasts of Turkey. A dozen colonies of the species were observed on rocks and the rhizomes of Posidonia oceanica meadows during the coral surveys carried out between 2012 and 2014. This record shows the northernmost occurrence of species in terms of geographic distribution in the Turkish coasts. The number of known species for the Anthozoan fauna of Turkey has increased to 76 with this new record.

In this work we describe Actinia ebhayiensis sp. nov. from South Africa. The species is externally similar to the type species of the genus, Actinia equina, from which it can be distinguished by nematocyst and allozyme data. Actinia ebhayiensis has a smooth, red column, with well-delimited parapet leading to a deep fosse where conspicuous blue acrorhagi can be found. Tentacles and oral disc are crimson red, and the pedal disc has a lighter pink colour. The microbasic p-mastigophores and b-mastigophores of the mesenterial filaments of the new species are significantly smaller than those of A. equina. Actinia ebhayiensis can also be clearly distinguished from other species of the genus in nematocyst measurements, genetic data and muscle morphology.

Savalia savaglia (Anthozoa: Zoantharia) is an uncommon, large, arborescent, modular species best known from the western basin of the Mediterranean Sea, and recorded recently from the Canary Islands. During dives in the Ría de Arousa (Galicia, north-western Spain, north-eastern Atlantic), four colonies were seen at a depth of 26–29 m, and identified by morphological study, including the cnidome, and DNA sequencing. These new records extend considerably the distribution of the species. Given that S. savaglia lives in the north-west of the Iberian Peninsula, overlooked old records from the literature further north from the Bay of Biscay may be reliable.

The lobate ctenophore Mnemiopsis leidyi is a periodically abundant and voracious plankton predator in coastal waters along the east coast of the United States. In the 1980s it was accidentally introduced to the Black Sea where it caused a dramatic reduction in fisheries. We investigated how M. leidyi is affected by infestation with parasitic larvae of the sea anemone Edwardsia lineata. Infested M. leidyi contained 1–30 (median 7) E. lineata larvae. Within M. leidyi most larvae had their mouth in the gastrovascular system near the aboral end of the pharynx. Parasitic E. lineata ingested all food previously ingested and pre-digested by M. leidyi. Non-infested M. leidyi had higher growth rates than infested individuals, which had zero or negative growth rates. Egg production was similar for infested and non-infested M. leidyi of similar size. Simulation based on the empirical data suggests that growing, non-infested, M. leidyi are expected to have a larger life-time egg production than infested shrinking individuals. E. lineata could be at least partially responsible for the sharp decline of M. leidyi populations in fall in US coastal waters. Advantages and disadvantages of E. lineata as a potential candidate for the control of the artificially introduced M. leidyi population in the Black Sea are discussed.

An abundant population of the sea pen Cavernularia pusilla (Anthozoa: Pennatulacea), with up to 70 colonies m−2, has been found on soft bottoms off the Basque coast (south-east Bay of Biscay, north-east Atlantic). This species spreads in an area of several kilometres length, and its bathymetric distribution ranges between 35 and 85 m depth, reaching its highest densities at 45–55 m. Such a population is remarkable, considering the scarce available records of this species and its southern affinities. The geographic and bathymetric distributions of the species are revised and discussed.

The known geographical distribution of the colonial scleractinian coral Cladocora debilis has been extended with a new record from the eastern Adriatic Sea. This scleractinian coral was found in spring 2002 on the cliff at the south of Lastovo Island (south Adriatic). The new record reported here is the first confirmation of C. debilis presently living in the Adriatic Sea.

Examination of recent pennatulacean material collected during several cruises off the Atlantic coast of Africa has allowed the taxonomic reassessment of several taxa of veretillid sea pens that were previously poorly known. The holotype of Cavernularia elegans (Herklots, 1858) is redescribed with the result that all previous records of the species from western Africa should be considered incorrect, as the taxon is here considered to be limited in distribution to Japan. A new species of the genus Cavernularia is described and compared with its congeners and a new veretillid genus and species are described. New taxa are based on specimens from western Africa.