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The taxonomy of ribbon worms (Nemertea) is particularly challenging due to the sparsity of distinct morphological characters, causing a significant underestimation of the group’s true diversity. The number of named deep-sea species is very limited and there is a vast number of undescribed deep-sea nemerteans still to be discovered. In this paper we figuratively ‘cut the ribbon’ and name seven new species of monostiliferous hoplonemerteans from seeps and seamounts along the Costa Rican margin, one from seeps along the Oregon margin, and one from vents of the Juan de Fuca Ridge, USA. The species Chernyshevia escarpiaphila gen. et sp. nov. and five species of the genus Alvinonemertes gen. nov. (Alvinonemertes dariae gen. et sp. nov., Alvinonemertes dagmarae gen. et sp. nov., Alvinonemertes christianeae gen. et sp. nov., Alvinonemertes claudiae gen. et sp. nov., Alvinonemertes tatjanae gen. et sp. nov.) represent Oerstediina, whereas the three species Tetrastemma sundbergi sp. nov., Tetrastemma polyakovae sp. nov., and Tetrastemma strandae sp. nov. represent Amphiporina. One species of tubulanid palaeonemerteans is described but not provided with a species name due to lacking sequence data for comparison. Additionally, we provide sequence data for one lineid heteronemertean, one reptant hoplonemertean, and two further eumonostiliferan hoplonemertean species. We use an integrative, turbotaxonomic approach combining DNA sequence data with concise morphological descriptions and fully digitized serial histological sections made available as cybertypes.

Family Tubulanidae Bürger, 1904 Tubulanidae is the only palaeonemertean family that was represented in the Costa Rican samples. In total, six tubulanid specimens were collected at depths around 1000 m from two nearby localities (Mound 11 & Mound 12). A DNA analysis of four specimens collected over different years showed that all specimens belong to the same species that is firmly nested within Tubulanidae (Fig. 2)., Published as part of Sagorny, Christina, Döhren, Jörn von, Rouse, Greg W. & Tilic, Ekin, 2022, Cutting the ribbon: bathyal Nemertea from seeps along the Costa Rica margin, with descriptions of 2 new genera and 9 new species, pp. 132-174 in European Journal of Taxonomy 845 (1) on page 142, DOI: 10.5852/ejt.2022.845.1959, http://zenodo.org/record/7258852, {"references":["Burger O. 1904. Nemertini. In: Das Tierreich 20. Lieferung Platyhelminthes. R. Friedlander & Sohn, Berlin."]}

Tubulanus cf. lutescens Cantell, 2001 Figs 3A–B, 4 Diagnosis Tubulanus cf. lutescens can be clearly identified as a member of the genus Tubulanus based on the amount of body wall, proboscis, and rhynchocoel muscle layers, the position of the nervous system, the composition of the cerebral organs, and several other internal characteristics (Gibson 1982; Sundberg & Hylbom 1994; Gibson & Sundberg 1999). As in other members of the genus, the body wall is composed of three muscle layers (outer circular, median longitudinal, and inner circular musculature), whereas the proboscis is composed of two layers (outer longitudinal, inner circular) and the rhynchocoel wall of only one circular muscle layer. The nervous system is located between the epidermal basement membrane and the outer circular body wall musculature and the cerebral organs consist of ciliated canals in the epidermis. Moreover, a mid-dorsal blood vessel and eyes are absent. The collected specimens are of bright red coloration and lacks a conspicuous colour pattern. A lower dorsal nerve is absent. Material examined COSTA RICA • 1 spec. (fixed in paraformaldehyde and prepared as 67 slides with transverse sections); methane seep Mound 12; 8.930° N, 84.313° W; depth 990–999 m; 22 May 2017; Lisa Levin and Charlotte Seid leg.; collected by HOV Alvin, Dive 4907; SIO-BIC N277 (ex SIO-BIC N233) (image series: https://doi.org/10.5281/zenodo.6368041) • 1 spec. (anterior fixed in paraformaldehyde, posterior fixed in ethanol); same collection data as for preceding; GenBank: ON186263, ON036061, ON021853, ON182046; SIO-BIC N233 • 1 spec. (fixed in paraformaldehyde); same collection data as for preceding; MZUCR Nemertea Collection MZUCR-103-01 (ex SIO-BIC N233) • 1 spec. (piece in ethanol); methane seep Mound 11; 8.920° N, 84.306° W; depth 1019–1045 m; 26 Feb. 2009; Greg Rouse and Mike Skowronski leg.; collected by HOV Alvin, Dive 4505; GenBank: ON186261, ON036062, ON021852, ON182043; SIO-BIC N107 • 1 spec. (piece in ethanol); methane seep Mound 12; 8.931° N, 84.313° W; depth 982–1000 m; 7 Jan. 2010; Lisa Levin and Graham Nash leg.; collected by HOV Alvin, Dive 4586; GenBank: ON186262, ON036063, ON021854, ON182044; SIO-BIC N120 • 1 spec. (ethanol); methane seep Mound 12; 8.93037° N, 84.31319° W; depth 996 m; 20 Oct. 2018; Lisa Levin and Kyle Metcalfe leg.; collected by HOV Alvin, Dive 4974; GenBank: ON186264, ON036060, ON021851, ON182045; SIO-BIC N257. Description Specimens up to 20 cm in length, up to 4 mm in diameter. Body more or less cylindrical. Tapered head slightly wider than rest of body (Fig. 3A). One pair of dorsal, V-shaped cephalic furrows in front of brain lobes (Fig. 3B). Body bright red, trunk slightly translucent. Anterior tip brighter than rest of head (Fig. 3A–B). Epidermal constrictions along whole body length. Gut and gonads visible through body wall (Fig 3A). Epidermis in foregut region 150–200 µm thick. Body wall composed of outer circular, middle longitudinal and inner circular musculature (Fig. 4E). Rhynchocoel wall only with circular muscle layer (Fig. 4E). Proboscis with two layers of musculature (outer longitudinal, inner circular), with two nerves, no proboscis armature (Fig. 4C). Proboscis pore subterminal, ventral (Fig. 4A); mouth opening separate, behind cerebral ganglia (Fig. 4B). Cerebral ganglia with only outer neurilemma, neurochord cells absent. Dorsal and ventral ganglia fused, located in ventral part of head (Fig. 4D). Lateral nerve cords without accessory nerves, myofibrillae absent (Fig. 4F). Precerebral nerves numerous, not grouped (Fig. 4A); buccal nerves paired. Upper dorsal nerve present (Fig. 4E). Nervous system between epidermal basement membrane and outer circular body wall musculature (Fig. 4D, F). Eyes lacking. Cerebral organs as simple ciliated canals in epidermis, posterior to ventral ganglia (Fig. 4D). Apical organ as depression frontal of rhynchopore, cephalic glands in anterior half of head, scattered between muscle fibres of head. Blood vascular system consisting of cephalic loop giving rise to two paired postcerebral, lateral vessels (Fig. 4A–B). Mid-dorsal blood vessel absent, smaller vessels splitting from lateral blood vessels in foregut region. Remarks The Costa Rican specimens are attributed to the genus Tubulanus, based on the phylogenetic analyses and the similarity of external and internal characteristics. In the phylogenetic analysis, this species belongs to a highly supported clade containing Tubulanus eozensis Yamaoka, 1940, Tubulanus polymorphus, and an undescribed tubulanid from the Sea of Okhotsk (Fig. 3). A clade of undescribed abyssal and hadal tubulanids is sister to that clade. The pairwise distances of the COI gene between the four deepsea specimens are below 1%. Interestingly, pairwise distances between Tubulanus cf. lutescens and two sequences of Tubulanus lutescens, a shallow water species collected in Sweden, are only 1–1.3%. In a TCS haplotype network analysis of the mitochondrial COI gene Tubulanus lutescens is only separated from our specimens by six nucleotide substitutions (Fig. 3). However, the two species differ by body coloration as Tubulanus cf. lutescens is bright red, whereas Tubulanus lutescens is yellow. Moreover, Tubulanus cf. lutescens lacks a lower dorsal nerve which is present in Tubulanus lutescens. The markedly dissimilar habitats of both species (T. lutescens intertidal from Northern Europe vs T. cf. lutescens from ca 1000 m depth in Eastern Pacific) might indicate that they represent different species. Future analyses of nuclear sequences of T. lutescens are warranted to determine whether Tubulanus cf. lutescens and T. lutescens are indeed two different species., Published as part of Sagorny, Christina, Döhren, Jörn von, Rouse, Greg W. & Tilic, Ekin, 2022, Cutting the ribbon: bathyal Nemertea from seeps along the Costa Rica margin, with descriptions of 2 new genera and 9 new species, pp. 132-174 in European Journal of Taxonomy 845 (1) on pages 142-144, DOI: 10.5852/ejt.2022.845.1959, http://zenodo.org/record/7258852, {"references":["Cantell C. - E. 2001. On the anatomy and taxonomy of Tubulanus lutescens n. sp. (Nemertini) from the West Coast of Sweden. Ophelia 54: 213 - 221. https: // doi. org / 10.1080 / 00785236.2001.10409467","Gibson R. 1982. British Nemerteans. Cambridge University Press, Cambridge.","Sundberg P. & Hylbom R. 1994. Phylogeny of the nemertean Subclass Palaeonemertea (Anopla, Nemertea). Cladistics 10: 347 - 402. https: // doi. org / 10.1006 / clad. 1994.1025","Gibson R. & Sundberg P. 1999. Six new species of palaeonemerteans (Nemertea) from Hong Kong. Zoological Journal of the Linnean Society 125: 151 - 196. https: // doi. org / 10.1111 / j. 1096 - 3642.1999. tb 00590. x"]}

The testis morphology, spermatogenesis, and the spermatozoon structure in two palaeonemerteans, Callinera sp. and Parahubrechtia sp., have been examined by light, laser confocal, and electron microscopy. Early spermatogenesis is quite similar between the two species. The similarities include the formation of the initial proacrosomal vesicle at the primary spermatocyte stage, the presence of electron-dense non-membranous substance around the centrioles in spermatogonia and spermatocytes, and the occurrence of lipid droplets at those stages. However, some differences in the process of acrosome formation during spermiogenesis were also found. In Callinera sp., a spherical acrosomal vesicle (rounded in the sections) transforms into a convex disk structure (arc-shaped in the longitudinal sections) in the developing posterior part of the spermatid and then migrates anteriorly; in Parahubrechtia sp., a rounded acrosomal vesicle migrates towards the apex of the cell where it is transformed into the arc-shaped structure. Both species have spermatozoa of a primitive type, i.e., with a small acrosomal complex, a rounded nucleus, a short mid-piece, and a posteriorly oriented flagellum. Nevertheless, some modifications in the sperm organization such as the asymmetric location of the acrosomal complex and mid-piece were recorded. It is possible that such modifications are synapomorphic for palaeonemerteans. In Callinera sp., the mid-piece contains 2–4 mitochondria, while Parahubrechtia sp. has only one ring-shaped but unclosed mitochondrion. The presence of several mitochondria in Callinera sp. may be regarded as a result of the so-called ‘progenetic spermatogenesis’.

The genus Carinina Hubrecht, 1885 has long been considered the most ‘archaic’ nemertean taxon because its members are distinguished by the basiepidermal position of the brain and lateral nerve cords, characters thought to be plesiomorphic for the phylum. Here we describe two new species, Carinina yushini sp. nov. from the Sea of Japan (Russia) and C. chocolata sp. nov. from the north-east Pacific (Oregon, USA), distinguished by brown body colour. A phylogenetic analysis based on partial sequences of five nuclear and mitochondrial gene regions, 18S rRNA, 28S rRNA, histone H3, 16S rRNA and COI, confirms the monophyly of Carinina (Family Carininidae), and points to a close relationship to Carinoma (Family Carinomidae). The two groups together form a sister clade to the rest of the palaeonemerteans (Family Tubulanidae + Family Cephalotrichidae s.l.). Carinina plecta most likely belongs to the Tubulanidae. A morphological synapomorphy of the clade Carininidae + Carinomidae is a larva with a single midventral eye (in contrast to eyeless larvae of the Tubulanidae and two-eyed larvae of the Cephalotrichidae). Our phylogenetic analysis suggests that the basiepidermal position of the central nervous system is an autapomorphy of Carininidae (and, independently, C. plecta), rather than a plesiomorphy of the phylum Nemertea or the class Palaeonemertea, emphasising that the genus Carinina is no more archaic than any other palaeonemertean genus.

From a biodiversity survey of a subterranean habitat near Sinan County, Guizhou Province, southwestern China, a new atyid shrimp of the genus Caridina H. Milne Edwards, 1837, C. sinanensissp. nov. was discovered. The new species can be separated from other congeners based on a combination of characters including depigmentation in body and reduction of eyes, small pigment spot at the centre of the cornea, the shape of rostrum and the endopod of the 1st male pleopod, and the relatively longer appendix interna on the appendix masculina of the 2nd pleopod. Mitochondrial COI and 16S rRNA gene sequences also support the establishment of the new species. Information on the habitat, and the levels of threat are discussed to guide the conservation of C. sinanensissp. nov.

This article provides an overview of the species composition of the phylum Nemertea in the Far Eastern seas of Russia. The list of nemerteans includes at least 200 species from the classes Palaeonemertea, Pilidiophora, and Hoplonemertea. Many of the species proved to be new to science; most of them remain undescribed. Currently, the use of gene markers is often the only approach to discriminating between closely related species and identifying them accurately. The well-studied nemertean fauna of Peter the Great Bay (73 species), Sea of Japan, has become a basis for comprehensive studies of these invertebrates at the Zhirmunsky National Scientific Center of Marine Biology, Far Eastern Branch, Russian Academy of Sciences.

The taxonomic identity of the palaeonemertean Cephalothrix linearis (Rathke, 1799) has been obscure for nearly two centuries, because its original description applies to almost any congeners, including Cephalothrix filiformis (Johnston 1828) and Cephalothrix rufifrons (Johnston, 1837), which occur commonly in the North Sea and adjacent waters. In this paper, I redescribe C. linearis based on two topotypes from Bergen, one herein designated as the neotype for C. linearis, because Rathke’s original material is not extant; I invoke Article 70.3.2 of the International Code of Zoological Nomenclature to fix Planaria linearis Rathke, 1799 as the type species of Cephalothrix Örsted, 1843 for the sake of stability. From the neotype, I determined sequences of the 28S rRNA, 16S rRNA, and cytochrome c oxidase subunit I (COI) genes. Using the COI sequence, I inferred the phylogenetic position of C. linearis along with 316 cephalotrichid sequences currently available in public databases. A tree-based species delimitation analysis detected 43 entities among them, with 34 in Cephalothrix and nine in eitherBalionemertes or Cephalotrichella. I apply valid species names to 12 of the 34 entities in Cephalothrix. I tabulated a total of 36 nominal species that are likely the members of the genus; the following five were excluded even though their specific names were originally combined with Cephalothrix: Cephalothrix armata Ulyanin, 1870 [Monostilifera, possibly Emplectonema gracile (Johnston, 1837)], Cephalothrix fragilis Bürger, 1892 [now Cephalotrichella signata (Hubrecht, 1879)], Cephalothrix signata Hubrecht, 1879 [now in Cephalotrichella], Cephalothrix unipunctata Parfitt, 1867 [now Tetrastemma melanocephalum (Johnston, 1837) (Monostilifera)], and Cephalothrix viridis Chapuis, 1886 [possibly Heteronemertea]. The five names cephalothrix Diesing, 1850 (as Borlasia cephalothrix), kroyeri Diesing, 1850 (as Cephalothrix kroyeri), linearis Diesing, 1850 (as Borlasia linearis), lineata Claparède, 1862 (as Cephalothrix lineata), and oerstedii Diesing, 1850 (as Cephalothrix oerstedii) aredeclared nomenclaturally unavailable.

Tetrodotoxin (TTX) is a potent neurotoxin found in many marine and terrestrial animals, but only a few species, such as the ribbon worms of the genus Cephalothrix, accumulate it in extremely high concentrations. The intrabody distribution of TTX in highly toxic organisms is of great interest because it helps researchers to understand the pathways by which the toxin migrates, accumulates, and functions in tissues. Using immunohistochemistry with anti-TTX antibodies, the authors of this study investigated the toxin’s distribution inside the organs, tissues, and cells of Cephalothrix cf. simula. The cell types of TTX-positive tissues were identified by light microscopy. The main sites of TTX accumulation occurred in the secretory cells of the integuments, the microvilli of the epidermal ciliary cells, cephalic glands, the glandular epithelia of the proboscises, the enterocytes of the digestive systems, and nephridia. Obtained data suggest the toxin migrates from the digestive system through blood vessels to target organs. TTX is excreted from the body through the nephridia and mucus of epidermal cells.

A new nemertean species of the genus Cephalothrix from intertidal calcareous red algae off the Vietnam coast is described based on histological sections, confocal laser scanning microscopy, and nucleotide sequences of three nuclear (18S rRNA, 28S rRNA, H3) and two mitochondrial (COI, 16S rRNA) DNA fragments. Cephalothrix suni sp. nov. is characterized by a unique body colour pattern consisting of transverse brown on ventral body side. A molecular phylogenetic analysis of the family Cephalotrichidae using a multigene approach has identified three clades for Cephalothrix: Cephalothrix, Procephalothrix, and interstitial cephalotrichids. The new species belongs to clade Procephalothrix sensu Chernyshev & Kajihara 2019 and a subclade of species with red, orange, or dark yellow anterior tip.

Chernyshev, Alexei V., Polyakova, Neonila E. (2021): An integrative description of a new Cephalothrix species (Nemertea: Palaeonemertea) from the South China Sea. Zootaxa 4908 (4): 584-594, DOI: https://doi.org/10.11646/zootaxa.4908.4.10

Cephalothrix suni sp. nov. (Figs 1A, B; 2 A-I; 3A-I) urn:lsid:zoobank.org:act: 602F23A5-7D8A-47BF-AB88-10D40D72C6BA syn. Cephalothrix sp. VIE: Chen et al., 2010, tab. 2, N 21. Cephalothrix suni: Chernyshev, 2016, p. 288 (nomen nudum) Type material. Holotype No. 40373 (MIMB), slides with transverse sectionas, Nam Du Island (09��43��� N, 104��23��� E), South China Sea, Vietnam, May 15, 2010, intertidal, calcareous red algae, collected by A. V. Chernyshev. Paratype No. 40374 (MIMB), Van Phong Bay (12��34��� N, 109��24��� E), South China Sea, Vietnam, January 13, 2005, intertidal, calcareous red algae, collected by A. V. Chernyshev. Other material examined. Three specimens, Van Phong Bay (12��33��� N, 109��23��� E), South China Sea, Vietnam, January 18, 2005, intertidal, calcareous red algae, collected by A. V. Chernyshev. GenBank accession numbers. Holotype (KU 840272 ��� Sundberg et al. 2016; see Table 2), paratype (GU726621 ��� Chen et al. 2010). Etymology. The specific epithet honors Prof. Sun Shichun (Ocean University of China). Description. External features. Body 50���80 mm long but less than 1 mm wide. Bluntly rounded head not narrower than trunk; anterior tip of head red (holotype) or orange (paratype), demarcated posteriorly by white band (Fig 1). Eyes absent. Background colour pale yellowish; dark pigment present on ventral side only. Small round mouth rimmed by brown ring with thicker anterior and posterior margins; two thin brown longitudinal stripes connected with in posterior part of the ring and extend to gut region (Fig. 1). Gut region with transverse dark drown bands; very thin transverse ring (epidermal furrow?) runs through each band. Brown spots also arranged between bands, sometimes forming irregular longitudinal stripes. Worms crawl on the dorsal side of their bodies, with the ventral side facing up. Internal morphology. Body wall: E = 20���26 ��m, D = 5���8 ��m, OCM = 4���7 ��m, LM = 18���35 ��m; outer part of LM and inner part of split OCM present (Figs 2B; 3 C-E;); in cerebral and foregut regions, crisscrossed DM located between dermis and OCM (Fig. 2D, F); in foregut region, dorsal muscular cross present between OCM and rhynchocoel wall (Fig. 2F); very thin ICM adjoins ventral wall of anterior foregut portion and connected with musculature of lateral blood vessel (Fig. 2A, B, E); posterior foregut portion lacks ICM (Fig. 2C). Longitudinal muscle plate between rhynchocoel and digestive tract present (Fig. 2F). Proboscis musculature consists of OCM, DM, LM, and very thin ICM (Fig. 2G); large pseudocnidae 5.6���6.5 �� 1.9���2.5 ��m, small pseudocnidae 3.3���4.1 �� 0.9���1.3 ��m (Fig. 2H); proboscis epithelium with longer (23���26 ��m) and shorter (14���17 ��m) collars of sensory cells (Fig. 2I). Ratio of brain���head tip to brain���mouth distances 1: 1.4 (based on transverse sections). Gut epithelium with dark pigment (Fig. 3I). Four cephalic nerves present (Fig. 3A). Single large median ventral nerve extends backwards from ventral brain commissure (Fig. 3C) and forms two buccal nerves immediately in front of mouth (Fig. 3D); two buccal nerves (Fig. 3E, F) join together (Fig. 3G) and become invisible immediately behind mouth (Fig. 3H). Dorsal nerve located between DM and OCM (Fig. 2F). Blood system typical for cephalotrichids; rhynchocoel vessel of type A according to Kajihara���s (2010) classification (Fig. 3B). Mushroom-like excretory organs present. Comparison. Almost all species of the genus Cephalothrix s.l. have more or less uniformly coloured body without any pattern, except for Cephalothrix queenslandica which, the same as the new species, possesses a distinct colour pattern consisting of transverse brown bands. However, according to the original description (Sundberg et al. 2003), Cephalothrix queenslandica has a brown anterior tip (in contrast to orange or red tip in C. suni), transverse brown bands on the dorsal body surface (in contrast to the bands on the ventral surface in C. suni), and two cephalic nerves (in contrast to four ones in C. suni). The uncorrected p -distance between the 18S rRNA sequences (no other sequences for C. queenslandica are known) of C. queenslandica and C. suni constitutes 0.5%. For comparison, the p -distance between the 18S rRNA sequences of Cephalothrix hongkongiensis Sundberg, Gibson & Olsson, 2003 and C. suni is 0.2%. Geographical and ecological distribution. South China Sea, South Vietnam, Van Phong Bay, and off Nam Du Island; intertidal zone, among calcareous red algae. Remarks. C. suni is apparently the most common species of Cephalothrix in coastal waters off Vietnam. In addition, another Cephalothrix species (Chernyshev 2016; GenBank accession no. MW118027) has been found in coastal waters off Vietnam (Cu Lao Cham Islands). The latter is similar to the undescribed species C. fasciculus sensu Leasi & Norenburg 2014 from Belize (GenBank accession no. KM083814.1). Phylogenetic analysis. According to a phylogenetic analysis, the genus Cephalothrix is monophyletic and includes three highly supported clades: Cephalothrix sensu Chernyshev & Kajihara 2019, Procephalothrix sensu Chernyshev & Kajihara 2019, and ���interstitial cephalotrichids��� with two undescribed species. The new species belongs to clade Procephalothrix, where Cephalothrix suni, C. rufifrons (Johnston, 1837), C. hongkongiensis, Cephalothrix mokievskii Korotkevitsch, 1982 (see Chernyshev 2020), and C. simula (Iwata, 1952) form a highly supported subclade of species with orange, red, or dark yellow anterior tip. This subclade is sister to subclade with two undescribed Cephalothrix from Arctic and Antarctic waters. Recently, Chernyshev & Kajihara (2019) have shown that the name Procephalothrix may be ���resurrected��� for the clade that contains Cephalothrix filiformis (Johnston, 1828) (type species of Procephalothrix) and other species with the outer part of LM located between the lateral nerve cord and OCM., Published as part of Chernyshev, Alexei V. & Polyakova, Neonila E., 2021, An integrative description of a new Cephalothrix species (Nemertea: Palaeonemertea) from the South China Sea, pp. 584-594 in Zootaxa 4908 (4) on pages 588-591, DOI: 10.11646/zootaxa.4908.4.10, http://zenodo.org/record/4447032, {"references":["Chen, H., Strand, M., Norenburg, J. L., Sun, S., Kajihara, H., Chernyshev, A. V., Maslakova, S. A. & Sundberg P. (2010) Statistical Parsimony Networks and Species Assemblages in Cephalotrichid Nemerteans (Nemertea). PLoS One, 5 (9), e 12885. https: // doi. org / 10.1371 / journal. pone. 0012885","Chernyshev, A. V. (2016) Nemerteans of the coastal waters of Vietnam. In: Adrianov, A. V. & Lutaenko, K. A. (Eds.), Biodiversity of the Western Part of the South China Sea. Dalnauka, Vladivostok, pp. 279 - 314.","Sundberg, P., Kvist, S. & Strand, M. (2016) Evaluating the utility of single-locus DNA barcoding for the identification of ribbon worms (phylum Nemertea). PLoS ONE 11: e 0155541.","Sundberg, P., Gibson, R. & Olsson, U. (2003) Phylogenetic analysis of a group of palaeonemerteans (Nemertea) including two new species from Queensland and the Great Barrier Reef, Australia. Zoologica Scripta, 32, 279 - 296. https: // doi. org / 10.1046 / j. 1463 - 6409.2002.00032. x","Leasi, F. & Norenburg, J. L. (2014) The necessity of DNA taxonomy to reveal cryptic diversity and spatial distribution of meiofauna, with a focus on Nemertea. PLoS ONE, 9 (8), e 104385. https: // doi. org / 10.1371 / journal. pone. 0104385","Chernyshev, A. V. & Kajihara, H. (2019) Comparative muscular morphology in Archinemertea (Nemertea: Palaeonemertea). Zoomorphology, 138, 193 - 207. https: // doi. org / 10.1007 / s 00435 - 019 - 00440 - w"]}

A new species of tubulanid palaeonemertean, Tubulanus izuensis sp. nov., is described as the sixth member of the genus in Japanese waters, based on materials dredged at depths of 244–436 m. It can be differentiated from all the known congeners by the unique burnt-orange dorsal pattern consisting of a median longitudinal stripe and transverse bands on a white ground color. In a maximum-likelihood tree reconstructed with partial sequences of the 16S rRNA, cytochrome c oxidase subunit I, 18S rRNA, 28S rRNA, and histone H3 genes, Tubulanus was not monophyletic, while T. izuensis sp. nov. was more closely related to the type species T. polymorphusRenier, 1804 than some other congeners including T. punctatus (Takakura, 1898), T. rhabdotusCorrea, 1954, T. sexlineatus (Griffin, 1898), and T. tamiasKajihara, Kakui, Yamasaki & Hiruta, 2015.

Some nemertean species from the genus Cephalothrix accumulate tetrodotoxin (TTX) in extremely high concentrations. The current study is the first to provide high-performance liquid chromatography&ndash, tandem mass spectrometry (HPLC&ndash, MS/MS) data on tetrodotoxin and its analogues (TTXs) profile and concentration in different regions and organs of Cephalothrix cf. simula, and its secretions produced in response to stimulation. Different specimens of C. cf. simula possessed 7&ndash, 11 analogues, including nine previously found in this species and two new for nemerteans&mdash, 4,9-anhydro-8-epi-5,6,11-trideoxyTTX and 1-hydroxy-8-epi-5,6,11-trideoxyTTX. The study of the toxins&rsquo, distribution in different regions and organs of nemerteans revealed the same qualitative composition of TTXs throughout the body but differences in the total concentration of the toxins. The total concentration of TTXs was highest in the anterior region of the body and decreased towards the posterior, the ratio of the analogues also differed between regions. The data obtained suggest a pathway of TTXs uptake in C. cf. simula and the role of toxins in the life activity of nemerteans.

Kajihara, Hiroshi (2020): Three Species of Ribbon Worms (Nemertea) from Cebu, the Philippines. Species Diversity 25: 251-273, DOI: 10.12782/specdiv.25.251

Knowledge on the detailed body plan in Palaeonemertea (a group putatively considered to retain ancestral character states within Nemertea) is essential in understanding the morphological evolution among not only nemerteans but also the rest of bilaterians in general; however, such information has been scanty in previous literature. In this study, we examined the body wall musculature, the position of the nervous system, and the musculature of the proboscis apparatus in 14 species of Archinemertea (a palaeonemertean clade comprised of Cephalotrichidae and Cephalotrichellidae) using confocal laser scanning microscopy with phalloidin labeling as well as classical Mallory’s trichrome staining. Unexpectedly, all the archinemerteans possessed a diagonal muscle layer lying directly ‘above’—instead of ‘below’, as usually found in most vermiform animals—the body wall outer circular muscle layer, a character state that has never been reported among Bilateria except for some acoels and proseriates. We speculate that the aberrant position of the outer diagonal muscle layer might have been actualized as a result of a flip-flop in a genetic regulatory circuit that controls the body wall muscular morphogenesis, which must have happened independently among the bilaterian evolution at least once in Acoela (Xenacoelomorpha), Proseriata (Platyhelminthes), and Archinemertea (Nemertea), respectively. Based on available phylogenetic data and the results from the present observation, we reconstructed the evolution of morphological characters within Archinemertea and its subclades. The outer diagonal muscle layer is likely a synapomorphy for Archinemertea (Cephalotrichidae + Cephalotrichellidae). Members of Balionemertes and Cephalotrichella possess some unique states for palaeonemerteans in muscular morphology (muscular strand associated with lateral nerve cord; longitudinal muscles between brain and extraganglionic tissue; proboscis with outer longitudinal muscle strands). We propose that muscle fibers embedded in lateral nerve cords, termed myofibrillae, in hoplo- and heteronemerteans are homologous with the body wall longitudinal muscles near the lateral nerves surrounded by circular muscles.

About 50 nemertean species have been reported to live in symbiotic relationships with other invertebrates, but only two hoplonemertean species are associated with echinoderms (starfish). The palaeonemertean Cephalotrichella echinicola, sp. nov. is described from samples collected in Nha Trang Bay, Vietnam, South China Sea. The species is the first known nemertean associated with sea urchins (Metalia sternalis and M. spatagus), living on both the oral and the aboral surfaces of the host and freely moving among its spines. The internal morphology of the new species is described based on histological sections and confocal laser scanning microscopy with phalloidin and antibody labelling. Sequences of three nuclear gene markers (18S rRNA, 28S rRNA, and histone H3) and two mitochondrial gene markers (16S rRNA and COI) were compared with those of other palaeonemertean species, and a phylogenetic analysis suggested that C. echinicola is closest to the free-living Cephalotrichella alba Gibson & Sundberg, 1992. Both the morphological data and the phylogenetic analysis provide additional evidence for distinguishing the families Cephalotrichidae and Cephalotrichellidae and support the rejection of Cephalotrichella as a junior synonym of Cephalothrix. A new diagnosis of the genus Cephalotrichella is given. http://zoobank.org/urn:lsid:zoobank.org:pub:091B5D56-71B2-4F4C-9AD8-F666B4610DE2

6 pages, 3 figures, 2 tables, New data for Carinina ochracea Sundberg et al., 2009 are provided for the Iberian Peninsula, establishing the southernmost limit of its known distribution. This species was previously known from only two localities: the type locality in Tjärnö (Sweden) and Pouldohan (Brittany, France). The material examined here was obtained during a faunal survey in the Villaviciosa Estuary (Asturias, northern Iberian Peninsula). The identity of the new specimen was confirmed both by DNA barcoding and anatomical examination. The molecular divergence of all available sequences of this species for four molecular markers, cytochrome c oxidase subunit I (COI), 16S, 18S and 28S rDNA, is discussed. For COI, four polymorphic sites were found, indicating: 1) a nuclear pseudogene; 2) heteroplasmy; or 3) gene duplication of a region of the mitochondrial genome. Two previously overlooked morphological characters were found: the presence of a colour ring and a postfixation staining band (pigmented band), which is histologically characterized. This species is the 12th palaeonemertean and the 75th nemertean reported from Iberian waters, This study was supported by grant CGL2011-23306 from the Spanish government

The proboscis and rhynchocoel musculature of 56 nemertean species was studied using phalloidin labelling and confocal laser scanning microscopy. Six types of muscle layers are found in the anterior proboscis of the nemerteans: inner circular, inner diagonal, inner longitudinal, outer diagonal, outer circular, and outer longitudinal. Only the inner circular and inner longitudinal muscle layers are present in all the nemerteans studied. Ten types of arrangement of the proboscis musculature are described. Three primary types ('palaeotype', 'heterotype', and 'hoplotype') correspond to the three nemertean supergroups (Palaeonemertea, Heteronemertea, and Hoplonemertea). The evolutionary transformations of the initial 'palaeotype' proboscis proceeded in two primary ways: increasing bilateral symmetry (Callinera, Hubrechtella, and most of Heteronemertea) and increasing polyradial symmetry (Baseodiscidae, Oxypolellinae, and Hoplonemertea). The musculature of the middle portion of the proboscis differs among the three groups with armature: Palaeonemertea (genus Callinera), Polystilifera, and Monostilifera. The musculature of the stylet apparatus of the monostiliferous nemerteans is more complicated than that of the polystiliferous nemerteans, and consists of four muscle components--basal and anterior sphincters, radial and longitudinal musculature. Among the studied monostiliferans, the different components of the stylet musculature are developed to varying degrees. In addition, data on the structure of the rhynchocoel with interwoven musculature are provided. The taxonomic significance and phylogenetic interpretation of the proboscis and rhynchocoel musculature is discussed.

Recent investigations, based mostly on molecular data, have unraveled the evolutionary history of several common ribbon worm (phylum Nemertea) species and solidified the taxonomic status of many higher taxa within the group. However, a large proportion of enigmatic species have yet to be placed in a phylogenetic framework. We investigated the phylogenetic positions of 26 novel and/or perplexing nemertean species from the Sea of Okhotsk, the Sea of Japan, the Kuril–Kamchatka Trench, and Vietnam (including the first record of a reptant nemertean from the Far East seas of Russia). We conducted both maximum likelihood and parsimony analyses, utilizing four molecular loci—mitochondrial COI and 16S rRNA, as well as nuclear 18S rRNA and 28S rRNA—finding that the current classification for most of these species is corroborated by their phylogenetic placement. We then discuss the evolution of some unique morphological traits possessed by some of these species, using the molecular phylogeny as a backbone for our general conclusions.

The structure of pseudocnidae of 16 species of Palaeonemertea clade Archinemertea (= Cephalotrichida s.l.) was investigated with confocal laser, scanning, and transmission electron microscopy (TEM). All species of the genus Cephalothrix possess two kinds of pseudocnidae, large and small. Only one type of pseudocnida is present in Balionemertes and Cephalotrichella. TEM revealed variation in the ultrastructure of large and small pseudocnidae of four species of Cephalothrix. Pseudocnidae of Balionemertes, Cephalotrichella, and Cephalothrix differ in substructure: in Balionemertes and Cephalotrichella the medulla is located in the basal half of the pseudocnidae with а precore layer situated in the apical half, whereas in Cephalothrix spp. and other palaeonemerteans the medulla surrounds a precore layer. Our results confirm the division of archinemerteans into Cephalotrichidae (with genus Cephalothrix) and Cephalotrichellidae (with genera Cephalotrichella and Balionemertes). The synapomorphy of Cephalotrichidae is pseudocnida dimorphism and the synapomorphies of Cephalotrichellidae are the position of the pseudocnidae on epithelial ridges and the distinct organization of pseudocnida layers, specifically the relative position of the medulla and precore layers. The pseudocnida lateral process, one or more of which is present in most species observed, is a probable synapomorphy of the clade Archinemertea. This is the first application of pseudocnida features to distinguish super-generic nemertean taxa and the results suggest that pseudocnidae provide a useful source of characters for nemertean systematics.

A checklist of benthic ribbon worm species from the Caribbean coast of Colombia is presented, including synonyms, distributions, a photographic record, and the main morphologic characters of each species for a rapid identification. This is the first research focused broadly on nemerteans in Colombia. 54 specimens of nemerteans were hand-collected from the rocky littoral of two different localities, and identified according to personal experience and specialist literature. 13 species were found; of which 11 represent new records for the country. These species belong to eight different traditionally used families: Tubulanidae, Valenciniidae, Lineidae, Amphiporidae, Cratenemertidae, Emplectonematidae, Drepanophoridae and Ototyphlonemertidae. The most common and abundant species was Dushia atra. The biodiversity of nemerteans in Colombia seems to overlap with the nemertean fauna from Florida and Brazil, explained by the convergence of the North Brazil Current, Guiana Current, Caribbean Currents and the Panama-Colombia Contracurrent in the sampled region. The results of this work suggest that the Caribbean coast of Colombia is a region with a high diversity of nemerteans, and provide important taxonomic data for environmental assessments and future biological research.

Resolving the deep relationships of ancient animal lineages has proven difficult using standard Sanger-sequencing approaches with a handful of markers. We thus reassess the relatively well-studied phylogeny of the phylum Nemertea (ribbon worms)-for which the targeted gene approaches had resolved many clades but had left key phylogenetic gaps-by using a phylogenomic approach using Illumina-based de novo assembled transcriptomes and automatic orthology prediction methods. The analysis of a concatenated data set of 2,779 genes (411,138 amino acids) with about 78% gene occupancy and a reduced version with 95% gene occupancy, under evolutionary models accounting or not for site-specific amino acid replacement patterns results in a well-supported phylogeny that recovers all major accepted nemertean clades with the monophyly of Heteronemertea, Hoplonemertea, Monostilifera, being well supported. Significantly, all the ambiguous patterns inferred from Sanger-based approaches were resolved, namely the monophyly of Palaeonemertea and Pilidiophora. By testing for possible conflict in the analyzed supermatrix, we observed that concatenation was the best solution, and the results of the analyses should settle prior debates on nemertean phylogeny. The study highlights the importance, feasibility, and completeness of Illumina-based phylogenomic data matrices.

The limited knowledge about the relationships between environmental factors and the maturation and reproductive seasonality of nemerteans is mostly obtained from field studies, and in many cases is conjectural. Few species have been studied under well-controlled laboratory conditions. In this work, the effects of temperature and photoperiod on gonad development and spawning of Cephalothrix hongkongiensis were observed by rearing worms under different temperatures and photoperiods. Worms reared at 4°C and 6°C showed no growth or gonadal development, and all died within 109 days. At 8°C and 12°C, gonads could be seen from 90 days to the termination of the 360-day experiment, but no spawning was observed. Worms maintained at 16, 24, and 28°C showed both gonadal development and spawning, and matured faster at higher temperatures. Under a fixed temperature (16°C), photoperiod did not have any significant impact on maturation and spawning. It is likely that temperature plays a major role in regulating the maturation and reproductive cycle of C. hongkongiensis.

We compared the anatomy of the holotype of the palaeonemertean Cephalothrix simula ( Iwata, 1952 ) with that of the holotypes of Cephalothrix hongkongiensis Sundberg, Gibson and Olsson, 2003 and Cephalothrix fasciculus ( Iwata, 1952 ), as well as additional specimens from Fukue (type locality of C. simula) and Hiroshima, Japan. While there was no major morphological discordance between these specimens, we found discrepancies between the actual morphology and some statements in the original description of C. simula with respect to supposedly species-specific characters. Our observation indicates that these three species cannot be discriminated by the anatomical characters so far used to distinguish congeners. For objectivity of scientific names, topogenetypes of the mitochondrial cytochrome c oxidase subunit I (COI) sequences are designated for C. simula, C. hongkongiensis, and C. fasciculus. Analysis of COI sequence showed that the Hiroshima population can be identified as C. simula, which has been found in previous studies from Trieste, Italy, and also from both the Mediterranean and Atlantic coasts of the Iberian Peninsula, indicating an artificial introduction via (1) ballast water, (2) ship-fouling communities, or (3) the commercially cultured oyster Crassostrea gigas ( Thunberg, 1793 ) brought from Japan to France in 1970s. Cephalothrix simula is known to be toxic, as it contains large amounts of tetrodotoxin (TTX). We report here that the grass puffer Takifugu niphobles ( Jordan and Snyder, 1901 )-also known to contain TTX- consumes C. simula. We suggest that the puffer may be able to accumulate TTX by eating C. simula.