Ribbon worms (Nemertea) are a less-known group of invertebrates, specially challenging for taxonomic studies due to the scarcity of external morphological features. As a consequence, the number of known nemertean species might represent just a small fraction of the true diversity of the phylum. The present study increases the number of known ribbon worm species with the description of the accordion worm Pararosa vigarae sp. nov., a new genus and species of Heternonemertea from the northwest coast of Spain. We performed molecular phylogenetic analyses based on partial sequences of 16S rRNA, 18S rRNA, 28S rRNA, cytochrome c oxidase subunit I (COI) and histone H3 gene markers that indicated the newly identified specimens represent a new genus and species of heteronemertean in the family Lineidae. We also provide morphological data and images illustrating its unique behaviour, contracting its body into a series of rings similar to an accordion. Our results increase our knowledge on the diversity of an important but often overlooked invertebrate phylum and emphasize the need to combine morphological and molecular data to discover new ribbon worm species and better evaluate the true diversity of the phylum.

The marine ribbon worm genus Tetranemertes Chernyshev, 1992 currently includes three species: the type species T.antonina (Quatrefages, 1846) from the Mediterranean Sea, T.rubrolineata (Kirsteuer, 1965) from Madagascar, and T.hermaphroditica (Gibson, 1982) from Australia. Seven new species are described: T.bifrostsp. nov., T.ocelatasp. nov., T.majinbuuisp. nov., and T.pastafariensissp. nov. from the Caribbean Sea (Panamá), and three species, T.unistriatasp. nov., T.paulayisp. nov., and T.arabicasp. nov., from the Indo-West Pacific (Japan and Oman). As a result, an amended morphological diagnosis of the genus is offered. To improve nomenclatural stability, a neotype of Tetranemertesantonina is designated from the Mediterranean. The newly described species, each characterized by features of external appearance and stylet apparatus, as well as by DNA-barcodes, form a well-supported clade with T.antonina on a molecular phylogeny of monostiliferan hoplonemerteans based on partial sequences of COI, 16S rRNA, 18S rRNA, and 28S rRNA. Six of the seven newly described species, as well as T.rubrolineata, possess the unusual character of having a central stylet basis slightly bilobed to deeply forked posteriorly in fully grown individuals, a possible morphological synapomorphy of the genus. In addition, an undescribed species of Tetranemertes is reported from the Eastern Tropical Pacific (Panamá), increasing the total number of known species in the genus to eleven.

Nemerteans (also called Nemertines) are a phylum of predominantly marine worms that use toxins to capture prey and to defend themselves against predators. Hoplonemerteans have a proboscis armed with one or more stylets used in prey capture and are taxonomically divided into Order Monostilifera, whose members possess a single large proboscis stylet, and Order Polystilifera, whose members have multiple small stylets. Many monostiliferans contain alkaloidal toxins, including anabaseine, that stimulate and then desensitize nicotinic acetylcholine receptors that are present in all animals. These compounds also interact with pyridyl chemoreceptors in crustaceans, reducing predation and larval settlement. Anabaseine has been a lead compound in the design of alpha7 nicotinic acetylcholine receptor agonists like GTS-21 (also called DMXBA) to treat disorders of cognition such as Alzheimer's disease and schizophrenia. These drug candidates also display anti-inflammatory activities of potential medical importance. Most polystiliferans live deep in open oceans and are relatively inaccessible. We fortunately obtained two live specimens of a large benthic polystiliferan, Paradrepanophorus crassus (Pc), from the coast of Spain. MS and NMR analyses of the Ehrlich's reagent derivative allowed identification of anabaseine. A spectrophotometric assay for anabaseine, also based on its reaction with Ehrlich's reagent, revealed high concentrations of anabaseine in the body and proboscis. Apparently, the biosynthetic mechanism for producing anabaseine was acquired early in the evolution of the Hoplonemertea, before the monostiliferan-polystiliferan divergence.

The North Atlantic deep-water polynoid worm Neopolynoe chondrocladiae is involved in an exceptional symbiotic relationship with two hosts: the carnivorous sponges Chondrocladia robertballardi and Chondrocladia virgata. While this is an obligate symbiotic relationship, its real nature is unclear. We used a multidisciplinary approach to narrow down the type of symbiotic relationship between symbiont and hosts. Molecular connectivity analyses using COI and 16S suggest that N. chondrocladiae has high potential for dispersal, connecting sites hundreds of kilometres apart, likely aided by oceanographic currents. Microbial analyses on different anatomical parts of five Chondrocladia species suggest that the presence of the worm in C. robertballardi does not affect the microbiome of the sponge. MicroCT analysis on N. chondrocladiae show that it has dorsally oriented parapodia, which might prevent the worm from getting trapped in the sponge. A faecal pellet recovered from the worm suggests that the polynoid feeds on the crustacean prey captured by the sponge, something corroborated by our stable isotope analysis. Light and confocal microscopy images suggest that N. chondrocladiae elytra produce bioluminescence. We propose that the worm might use bioluminescence as a lure for prey (increasing the food available for both the sponge and the polynoid) and thus fuelling a mutualistic relationship.

The heteronemertean Cerebratulus marginatus Renier, 1804 is a well-known representative of the family Lineidae (Nemertea) inhabiting sandy or muddy sediments throughout the world. Due to its wide geographic distribution and the lack of distinctive external morphological features among different populations, the species has been considered cosmopolitan. Increasing evidence indicates that nemertean species, including Cerebratulus marginatus, described based on morphology are often not supported by genetic data and represent complexes of cryptic species, rather than cosmopolitan species. Here, we use species delimitation and phylogenetic analyses to evaluate the speciation patterns within the putative C. marginatus species complex. We examined 25 specimens morphologically ascribed to C. marginatus and closely related species using a multilocus dataset including two mitochondrial markers (16S rRNA, COI) and three nuclear markers (18S rRNA, 28S rRNA, H3). Our analyses identified at least four supported independent lineages among the populations analysed, indicating that samples identified as C. marginatus might represent indeed a complex of cryptic species. Therefore, our results do not support the cosmopolitanism of C. marginatus and provide additional evidence suggesting that species identifications in nemerteans should not be based exclusively on morphological or anatomical features which do not accurately reflect evolutionary patterns. Our study highlights the importance of including molecular data in addition to morphological information to accurately delimit species boundaries, thereby improving nemertean taxonomy by providing a more accurate picture of the true species diversity and geographic distribution of this typically neglected phylum.

1. Fasta file with the amplicon sequences included in the paper: "Sleeping with the enemy: unravelling the symbiotic relationships between the scale worm Neopolynoe chondrocladiae (Annelida: Polynoidae) and its carnivorous sponge hosts". This file contains 45,554 sequences from different species of the sponge Chondrocladia, sediment and water samples.2. Table with the number of counts for each sequence (rows) and each sample (columns). This file is the output of the software Mothur using the pipeline for amplicon sequences:https://mothur.org/wiki/miseq_sop/.

Located in the Cantabrian Sea (NE Atlantic), El Cachucho is the largest offshore Marine Protected Area (MPA) in Spain. One of the most abundant keystone megafauna species occurring in this MPA is a yellow gorgonian of genus Placogorgia Wright and Studer (1889), occurring in relatively high densities in steep slopes with rocky outcrops at depths ranging 500-1200 m. Here, we describe a new species of isopod, Astacilla andresmeixidei sp. nov., living in association with a specimen of a yellow gorgonian collected at 525 m depth. Females of the new species are characterised by a trapezoidal pereonite 4 with a middorsal bifurcate tubercle on posterior margin; males have a rectangular pereonite 4 with small tubercles irregularly distributed and pereonite 3 with a mid ventral process. The new species is distinguished from the most morphologically similar species Astacilla gorgonophila Monod (1925) by its dorsal sculpture, having a shorter antenna 2 with a flagellum of three articles plus a claw, and also by its geographic and bathymetric distribution. Phylogenetic analysis using the mitochondrial marker COI confirmed that the new isopod is a member of the family Arcturidae and placed it in a Glade, recovered with low support, including other species of the genus Astacilla Cordiner, 1793. As with other previously described arcturids, we suggest that A. andresmeixidei sp. nov. is a commensal of the gorgonian using its branches to reach higher in the water column and thus increase its chances to get more particulate organic matter. Our morphological analyses on the gorgonian host, suggest that it belongs to the genus Placogorgia although in our phylogenetic results using the nuclear marker msh1 the gorgonian shows affinities with the genus Paramuricea Kolliker (1865). This taxonomic inconsistency is discussed.

Zoologica ScriptaVolume 48, Issue 1 p. 118-119 LETTER TO THE EDITOR Nemertean taxonomy—Implementing changes in the higher ranks, dismissing Anopla and Enopla Malin Strand, Corresponding Author Malin Strand malin.strand@slu.se orcid.org/0000-0002-8144-9592 Swedish Species Information Centre, Swedish University of Agricultural Sciences, Uppsala, Sweden Correspondence Malin Strand, Swedish Species Information Centre, Swedish University of Agricultural Sciences, Uppsala, Sweden. Email: malin.strand@slu.seSearch for more papers by this authorJon Norenburg, Jon Norenburg Department of Invertebrate Zoology, Smithsonian National Museum of Natural History, Washington, District of ColumbiaSearch for more papers by this authorJosé E. Alfaya, José E. Alfaya LARBIM-IBIOMAR (CCT CONICET—CENPAT) & Facultad de Ciencias Naturales, Universidad Nacional de la Patagonia San Juan Bosco, Puerto Madryn, ArgentinaSearch for more papers by this authorFernando Ángel Fernández-Álvarez, Fernando Ángel Fernández-Álvarez Institut de Ciències del Mar (CSIC), Barcelona, SpainSearch for more papers by this authorHåkan S Andersson, Håkan S Andersson Department of Chemistry & Biomedical Sciences, Linnaeus University, Kalmar, SwedenSearch for more papers by this authorSonia C. S. Andrade, Sonia C. S. Andrade Departamento de Genetica e Biologia Evolutiva, IB-Universidade de Sao Paulo, Sao Paulo, BrazilSearch for more papers by this authorThomas Bartolomaeus, Thomas Bartolomaeus Institute of Evolutionary Biology and Animal Ecology, University of Bonn, Bonn, GermanySearch for more papers by this authorPatrick Beckers, Patrick Beckers Institute of Evolutionary Biology and Animal Ecology, University of Bonn, Bonn, GermanySearch for more papers by this authorGregorio Bigatti, Gregorio Bigatti LARBIM-IBIOMAR (CCT CONICET—CENPAT) & Facultad de Ciencias Naturales, Universidad Nacional de la Patagonia San Juan Bosco, Puerto Madryn, ArgentinaSearch for more papers by this authorIrina Cherneva, Irina Cherneva Biological Faculty, Lomonosov Moscow State University, Moscow, RussiaSearch for more papers by this authorAlexey Chernyshev, Alexey Chernyshev National Scientific Center of Marine Biology, Far Eastern Branch, Russian Academy of Sciences, Vladivostok, Russia Far Eastern Federal University, Vladivostok, RussiaSearch for more papers by this authorBrian M. Chung, Brian M. Chung Department of Zoology, Weber State University, Ogden, UtahSearch for more papers by this authorJörn von Döhren, Jörn von Döhren Institute of Evolutionary Biology and Animal Ecology, University of Bonn, Bonn, GermanySearch for more papers by this authorGonzalo Giribet, Gonzalo Giribet Museum of Comparative Zoology, Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MassachusettsSearch for more papers by this authorJaime Gonzalez-Cueto, Jaime Gonzalez-Cueto Grupo de Investigación MIKU, Facultad de Ciencias Básicas, Universidad del Magdalena, Santa Marta D.T.C.H. Magdalena, Santa Marta, ColombiaSearch for more papers by this authorAlfonso Herrera-Bachiller, Alfonso Herrera-Bachiller Departamento de Ciencias de la Vida, Universidad de Alcala, Alcalá de Henares, SpainSearch for more papers by this authorTerra Hiebert, Terra Hiebert Department of Biology, Institution of Ecology and Evolution, University of Oregon Eugene, Eugene, OregonSearch for more papers by this authorNatsumi Hookabe, Natsumi Hookabe Faculty of Science, Hokkaido University, Sapporo, JapanSearch for more papers by this authorJuan Junoy, Juan Junoy Departamento de Ciencias de la Vida, Universidad de Alcala, Alcalá de Henares, SpainSearch for more papers by this authorHiroshi Kajihara, Hiroshi Kajihara Faculty of Science, Hokkaido University, Sapporo, JapanSearch for more papers by this authorDaria Krämer, Daria Krämer Institute of Evolutionary Biology and Animal Ecology, University of Bonn, Bonn, GermanySearch for more papers by this authorSebastian Kvist, Sebastian Kvist Department of Natural History, Royal Ontario Museum, Toronto, Ontario, Canada Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, CanadaSearch for more papers by this authorTimur Yu Magarlamov, Timur Yu Magarlamov National Scientific Center of Marine Biology, Far Eastern Branch, Russian Academy of Sciences, Vladivostok, RussiaSearch for more papers by this authorSvetlana Maslakova, Svetlana Maslakova Department of Biology, Institution of Ecology and Evolution, University of Oregon Eugene, Eugene, OregonSearch for more papers by this authorCecili B. Mendes, Cecili B. Mendes Departamento de Genetica e Biologia Evolutiva, IB-Universidade de Sao Paulo, Sao Paulo, BrazilSearch for more papers by this authorRobert Okazaki, Robert Okazaki Department of Zoology, Weber State University, Ogden, UtahSearch for more papers by this authorChristina Sagorny, Christina Sagorny Institute of Evolutionary Biology and Animal Ecology, University of Bonn, Bonn, GermanySearch for more papers by this authorMegan Schwartz, Megan Schwartz University of Puget Sound, Tacoma, WashingtonSearch for more papers by this authorShi-Chun Sun, Shi-Chun Sun Institute of Evolution & Marine Biodiversity, Ocean University of China, Qingdao, ChinaSearch for more papers by this authorPer Sundberg, Per Sundberg Department of Marine Sciences, University of Gothenburg, Gothenburg, SwedenSearch for more papers by this authorJames M. Turbeville, James M. Turbeville Department of Biology, Virginia Commonwealth University, Richmond, VirginiaSearch for more papers by this authorCong-Mei Xu, Cong-Mei Xu Swedish Species Information Centre, Swedish University of Agricultural Sciences, Uppsala, Sweden National Scientific Center of Marine Biology, Far Eastern Branch, Russian Academy of Sciences, Vladivostok, RussiaSearch for more papers by this author Malin Strand, Corresponding Author Malin Strand malin.strand@slu.se orcid.org/0000-0002-8144-9592 Swedish Species Information Centre, Swedish University of Agricultural Sciences, Uppsala, Sweden Correspondence Malin Strand, Swedish Species Information Centre, Swedish University of Agricultural Sciences, Uppsala, Sweden. Email: malin.strand@slu.seSearch for more papers by this authorJon Norenburg, Jon Norenburg Department of Invertebrate Zoology, Smithsonian National Museum of Natural History, Washington, District of ColumbiaSearch for more papers by this authorJosé E. Alfaya, José E. Alfaya LARBIM-IBIOMAR (CCT CONICET—CENPAT) & Facultad de Ciencias Naturales, Universidad Nacional de la Patagonia San Juan Bosco, Puerto Madryn, ArgentinaSearch for more papers by this authorFernando Ángel Fernández-Álvarez, Fernando Ángel Fernández-Álvarez Institut de Ciències del Mar (CSIC), Barcelona, SpainSearch for more papers by this authorHåkan S Andersson, Håkan S Andersson Department of Chemistry & Biomedical Sciences, Linnaeus University, Kalmar, SwedenSearch for more papers by this authorSonia C. S. Andrade, Sonia C. S. Andrade Departamento de Genetica e Biologia Evolutiva, IB-Universidade de Sao Paulo, Sao Paulo, BrazilSearch for more papers by this authorThomas Bartolomaeus, Thomas Bartolomaeus Institute of Evolutionary Biology and Animal Ecology, University of Bonn, Bonn, GermanySearch for more papers by this authorPatrick Beckers, Patrick Beckers Institute of Evolutionary Biology and Animal Ecology, University of Bonn, Bonn, GermanySearch for more papers by this authorGregorio Bigatti, Gregorio Bigatti LARBIM-IBIOMAR (CCT CONICET—CENPAT) & Facultad de Ciencias Naturales, Universidad Nacional de la Patagonia San Juan Bosco, Puerto Madryn, ArgentinaSearch for more papers by this authorIrina Cherneva, Irina Cherneva Biological Faculty, Lomonosov Moscow State University, Moscow, RussiaSearch for more papers by this authorAlexey Chernyshev, Alexey Chernyshev National Scientific Center of Marine Biology, Far Eastern Branch, Russian Academy of Sciences, Vladivostok, Russia Far Eastern Federal University, Vladivostok, RussiaSearch for more papers by this authorBrian M. Chung, Brian M. Chung Department of Zoology, Weber State University, Ogden, UtahSearch for more papers by this authorJörn von Döhren, Jörn von Döhren Institute of Evolutionary Biology and Animal Ecology, University of Bonn, Bonn, GermanySearch for more papers by this authorGonzalo Giribet, Gonzalo Giribet Museum of Comparative Zoology, Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MassachusettsSearch for more papers by this authorJaime Gonzalez-Cueto, Jaime Gonzalez-Cueto Grupo de Investigación MIKU, Facultad de Ciencias Básicas, Universidad del Magdalena, Santa Marta D.T.C.H. Magdalena, Santa Marta, ColombiaSearch for more papers by this authorAlfonso Herrera-Bachiller, Alfonso Herrera-Bachiller Departamento de Ciencias de la Vida, Universidad de Alcala, Alcalá de Henares, SpainSearch for more papers by this authorTerra Hiebert, Terra Hiebert Department of Biology, Institution of Ecology and Evolution, University of Oregon Eugene, Eugene, OregonSearch for more papers by this authorNatsumi Hookabe, Natsumi Hookabe Faculty of Science, Hokkaido University, Sapporo, JapanSearch for more papers by this authorJuan Junoy, Juan Junoy Departamento de Ciencias de la Vida, Universidad de Alcala, Alcalá de Henares, SpainSearch for more papers by this authorHiroshi Kajihara, Hiroshi Kajihara Faculty of Science, Hokkaido University, Sapporo, JapanSearch for more papers by this authorDaria Krämer, Daria Krämer Institute of Evolutionary Biology and Animal Ecology, University of Bonn, Bonn, GermanySearch for more papers by this authorSebastian Kvist, Sebastian Kvist Department of Natural History, Royal Ontario Museum, Toronto, Ontario, Canada Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, CanadaSearch for more papers by this authorTimur Yu Magarlamov, Timur Yu Magarlamov National Scientific Center of Marine Biology, Far Eastern Branch, Russian Academy of Sciences, Vladivostok, RussiaSearch for more papers by this authorSvetlana Maslakova, Svetlana Maslakova Department of Biology, Institution of Ecology and Evolution, University of Oregon Eugene, Eugene, OregonSearch for more papers by this authorCecili B. Mendes, Cecili B. Mendes Departamento de Genetica e Biologia Evolutiva, IB-Universidade de Sao Paulo, Sao Paulo, BrazilSearch for more papers by this authorRobert Okazaki, Robert Okazaki Department of Zoology, Weber State University, Ogden, UtahSearch for more papers by this authorChristina Sagorny, Christina Sagorny Institute of Evolutionary Biology and Animal Ecology, University of Bonn, Bonn, GermanySearch for more papers by this authorMegan Schwartz, Megan Schwartz University of Puget Sound, Tacoma, WashingtonSearch for more papers by this authorShi-Chun Sun, Shi-Chun Sun Institute of Evolution & Marine Biodiversity, Ocean University of China, Qingdao, ChinaSearch for more papers by this authorPer Sundberg, Per Sundberg Department of Marine Sciences, University of Gothenburg, Gothenburg, SwedenSearch for more papers by this authorJames M. Turbeville, James M. Turbeville Department of Biology, Virginia Commonwealth University, Richmond, VirginiaSearch for more papers by this authorCong-Mei Xu, Cong-Mei Xu Swedish Species Information Centre, Swedish University of Agricultural Sciences, Uppsala, Sweden National Scientific Center of Marine Biology, Far Eastern Branch, Russian Academy of Sciences, Vladivostok, RussiaSearch for more papers by this author First published: 29 October 2018 https://doi.org/10.1111/zsc.12317Citations: 21Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. 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Three species of the isopod genus Astacilla were collected off Alborán Island (SW Mediterranean Sea) within the LIFE + INDEMARES project. Twelve specimens of the rare species Astacilla carlosteroi (Reboreda, Wägele & Garmendia, 1994) were found; this species is only known as a single incomplete female from Galicia (NW Spain, Atlantic). Males, reported for the first time, are described, as well as morphological details provided for two additional species, A. dilatata (G.O. Sars, 1883) and A. mediterranea Koehler, 1911.

The phylum Nemertea is an important component of the benthic ecosystems of the Southern Ocean, but its biodiversity is still relatively poorly known in Antarctic waters. There are few common and well-known nemertean species occurring in the shallow Antarctic waters, and these include the congeneric Antarctonemertes valida (Bürger, 1893) and Antarctonemertes riesgoae Taboada et al., 2013, two relatively small brooding hoplonemerteans whose females lay eggs inside cocoons. A third Antarctic member of the genus, Antarctonemertes belgica (Bürger, 1904), was reported only in the original description. Here we document the existence of a fourth Antarctic member of the genus Antarctonemertes originally described as Tetrastemma unilineatum Joubin, 1910. Our phylogenetic analysis resulted into the placement of the new Antarctonemertes in a robustly supported clade –Antarctic Antarctonemertes – containing the other two congeneric Antarctic species ( A. valida and A. riesgoae ), and pairwise COI molecular distances between the three species ranged from 5.2 to 6.2% ( p distance). The analysis of 104 COI sequences of the three species showed star-like haplotype networks, as in other studies on Antarctic invertebrates. Antarctonemertes unilineata comb. nov. is similar in shape to its Antarctic congeneric relatives and its most prominent morphological character is a dorsal mid-longitudinal band present along the body. We also document the presence of a cocoon built by females of A. unilineata comb. nov., a character shared with its Antarctic congeners analysed here. Although the four Antarctic Antarctonemertes species appear to overlap their distribution, A. riesgoae , A. valida and A. belgica appear in sympatry in the West Antarctic shores while A. unilineata comb. nov. has been mainly found in the East Antarctic shores and sub-Antarctic Islands.

Benthic monitoring of the marine shallow bottoms off Menorca (Balearic Islands, western Mediterranean) has yielded several specimens of the leptostracan genus Paranebalia Claus, 1880. This finding constitutes the first report of the genus from European latitudes and the Mediterranean Sea and therefore the third leptostracan genus known from the Mediterranean. Specimens are described, illustrated and compared to other known species; they might represent a new species but their state of maturity and the lack of an appropriate diagnosis for the type species of the genus, Paranebalia longipes (Willemöes-Suhm, 1875), did not allow to confirm its taxonomic status.