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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.

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.

Here, we report the complete mitochondrial genome of the marine nemertean Cephalothrix species collected from the coastal region of South Korea. The mitochondrial genome of Cephalothrix sp. South K...

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.

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.

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.

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.

Tubulanus mawsoni (Wheeler 1940) comb. nov. is redescribed based on the material collected during the Spanish Antarctic expedition Bentart-03 through the Bellingshausen Sea (Antarctica). Previously belonging to the genus Carinina Hubrecht 1885, the species is transferred to the genus Tubulanus based on the situation of the brain and lateral nerves between the basement membrane and the outer circular muscle layer, the presence of muscle crosses in the body wall, the position of the blood and excretory systems, the presence of proboscis nerves and the structure of the cerebral sensory organs, the rhynchocoel wall and the rhynchodaeal and buccal nerves. Microphotographs of the different regions of the body and the proboscis structure are provided for the first time. Based on the ambiguities between Tubulanus diagnosis and the species descriptions, as well as the possible paraphyletic status of the genus, the need for new morphological and molecular studies is suggested.http://zoobank.org/urn:lsid:zoobank.org...

Tubulanus rhabdotus Corr��a, 1955 (Figure 2 [1]) Tubulanus rhabdotus: Corr��a, 1955: 12, pl. 1, figs 1���6, pl. 2, figs 7���9, pl. 3, figs 10, 11, pl. 4, figs 12���18; Corr��a, 1961: 5, figs 5, 6; Corr��a, 1963: 42; Fox & Ruppert, 1985: 37; Norenburg, 1985: 40, fig. 4; Jespersen & L��tzen, 1987: 187; Jespersen, 1994: 124; Gibson, 1995: 531; Reunov & Klepal, 1997: 132; Stricker et al. 2001: 225; Thollesson & Norenburg, 2003: 409; Ritger & Norenburg, 2006: 932; Santos & Norenburg, 2011. Material examined. One specimen, MZUSP 0 0 0 0 1, Brazil, Cear��, S��o Gon��alo do Amarante, Pec��m harbor, 3 �� 32.08 ��� S 38 �� 47.78 ��� W, on settlement plates, coll. PROCAD team, 29.I. 2010. Two specimens, MZUSP 0 0 0 0 2, Brazil, Cear��, S��o Gon��alo do Amarante, Pec��m harbor, 3 �� 32.08 ��� S 38 �� 47.78 ��� W, on settlement plates, coll. PROCAD team, 13.X. 2010. Three specimens, MZUSP 0 0 0 0 3, Brazil, Cear��, S��o Gon��alo do Amarante, Pec��m harbor, 3 �� 32.08 ��� S 38 �� 47.78 ��� W, on settlement plates, coll. PROCAD team, 12.VIII. 2011. One specimen, MZUSP 0 0 0 0 4, Brazil, Cear��, S��o Gon��alo do Amarante, Pec��m harbor, 3 �� 32.08 ��� S 38 �� 47.78 ��� W, on settlement plates, coll. PROCAD team, 01.IX. 2011. One specimen, MZUSP 0 0 0 0 5, Brazil, Cear��, S��o Gon��alo do Amarante, Pec��m harbor, 3 �� 32.08 ��� S 38 �� 47.78 ��� W, on settlement plates, coll. PROCAD team, 01.XI. 2011. One specimen, MZUSP 0 0 0 0 6, Brazil, Cear��, S��o Gon��alo do Amarante, Pec��m harbor, 3 �� 32.08 ��� S 38 �� 47.78 ��� W, on settlement plates, coll. PROCAD team, 16.VIII. 2012. Two specimens, MZUSP 0 0 0 0 7, Brazil, Cear��, S��o Gon��alo do Amarante, Pec��m harbor, 3 �� 32.08 ��� S 38 �� 47.78 ��� W, on settlement plates, coll. PROCAD team, 20.XI. 2012. One specimen (26 mm long after preservation), MZUSP 0 0 0 0 8, Brazil, Cear��, Caucaia, Praia do Pacheco, 3 �� 41.11 ' S 38 �� 37.91 ' W, between algae, coll. Cecili Mendes, 03.I. 2013. Field diagnosis. Body beige with transverse black rings variably spaced; color persists after fixation; first four rings widest; first ring with median constriction dorsally, interrupted ventrally by mouth. Body with scattered small black dots surrounded by greenish halos; halos can disappear after fixation. Lateral sensory organs visible at fourth black ring as non-pigmented small circular depressions. No eye spots evident. Rhynchopore sub-terminal near anterior margin of cephalic lobe. Distribution. Western Atlantic: USA (Florida [Corr��a 1961]; South Carolina [Fox & Ruppert 1985]); Panama (Bocas del Toro region [Norenburg unpublished data]); Cura��ao (Gibson 1995); Brazil (Cear�� [present study] and S��o Sebasti��o [Corr��a 1955]). Ecology. Worms of this species live in the littoral zone, between algae on rocks, on recruitment plates, on old mangrove roots, under logs in tide pools, in seagrass or algae beds (Corr��a 1955; Corr��a 1961). Most of the specimens in this study were found on offshore recruitment plates installed at Pec��m harbor but one was found among algae. These animals, as others of the genus, produce thin cellophane-like tubes in which they shelter (Corr��a 1961). None of the specimens found in this study were encased in those tubes, some tubes were found on the recruitment plates. Remarks. The only species that can be confused with T. rhabdotus is Tubulanus riceae Ritger and Norenburg, 2006; however adult specimens of the latter generally are smaller, body ground color is whitish, and the lateral sensory organs are in the third dark ring (in the fourth black ring in T. rhabdotus). Specimens collected during the PROCAD project could not be measured because most of them fragmented during the fixation process. Two specimens remained intact and measured 92 mm and 75 mm long. Corr��a (1955; 1961; 1963) reports specimens up to 25 mm long., Published as part of Mendes, Cecili B., Matthews-Cascon, Helena & Norenburg, Jon L., 2016, New records of ribbon worms (Nemertea) from Cear��, Northeast Brazil, pp. 146-156 in Zootaxa 4061 (2) on page 148, DOI: 10.11646/zootaxa.4061.2.4, http://zenodo.org/record/263586, {"references":["Correa, D. D. (1955) Nemertinos do Litoral Brasileiro. Boletim da Faculdade de filosofia, ciencias e letras, Universidade de Sao Paulo, 19, 1 - 119.","Correa, D. D. (1961) Nemerteans from Florida and Virgin Islands. Bulletin of Marine Science of the Gulf and Caribbean, 11, 1 - 44.","Correa, D. D. (1963) Nemerteans from Curacau. Studies on the Fauna of Curacau and other Caribbean islands, 17, 41 - 56.","Fox, R. S. & Ruppert, E. E. (1985) Shallow-Water Marine Benthic Macroinvertebrates of South Carolina. Species Identification, Community Composition, and Symbiotic Associations. Belle W. Baruch Library in Marine Science No. 14. University of South Carolina Press, Columbia, SC, 43 pp.","Norenburg, J. L. (1985) Structure of the nemertine integument with consideration of its ecological and phylogenetic significance. American Zoology, 25, 37 - 51.","Jespersen, A. & Lutzen, J. (1987) Ultrastructure of the nephridio-circulatory connections in Tubulanus annulatus (Nemertini, Anopla). Zoomorphology, 107, 181 - 189. http: // dx. doi. org / 10.1007 / BF 00312311","Jespersen, A. (1994) Spermiogenesis, sperm structure and fertilization in the palaeonemertean Cephalothrix rufifrons (Nemertini, Anopla). Zoomorphology, 114, 119 - 124. http: // dx. doi. org / 10.1007 / BF 00396644","Gibson, R. (1995) Nemertean genera and species of the world: an annotated checklist of original names and description citations, synonyms, current taxonomic status, habitats and recorded zoogeographic distribution. Journal of Natural History, 29, 271 - 562. http: // dx. doi. org / 10.1080 / 00222939500770161","Reunov, A. A. & Klepal, W. (1997) Ultrastructural investigation of spermatogenesis in the nemertine worm Procephalothrix sp. (Palaeonemertini, Anopla). Helgolander Meeresunters, 51, 125 - 135. http: // dx. doi. org / 10.1007 / BF 02908703","Stricker, S. A., Smythe, T. L., Miller, L. & Norenburg, J. L. (2001) Comparative biology of oogenesis in nemertean worms. Acta Zoologica, 82, 213 - 230. http: // dx. doi. org / 10.1046 / j. 1463 - 6395.2001.00080. x","Thollesson, M. & Norenburg, J. L. (2003) Ribbon worm relationships: a phylogeny of the phylum Nemertea. The Royal Society, 270, 407 - 415. http: // dx. doi. org / 10.1098 / rspb. 2002.2254","Ritger, R. K. & Norenburg, J. L. (2006) Tubulanus riceae new species (Nemertea: Anopla: Palaeonemertea: Tubulanidae), from South Florida, Belize and Panama. Journal of Natural History, 40, 931 - 942. http: // dx. doi. org / 10.1080 / 00222930600833867","Santos, C. & Norenburg, J. L. (2011) Nemertea. In: Amaral, A. C. Z. & Nallin, S. A. H. (Eds.), Biodiversidade e Ecossistemas Marinhos do Litoral Norte de Sao Paulo Sudeste do Brasil. Biota FAPESP, Campinas, pp. 85 - 99."]}

Carinomella cf. lactea Coe, 1905 (Figure 2 [2 a��� 2 b]) Carinomella lactea: Coe, 1905: 127, Pl. 5, figs. 45���49, Pl. 6, figs. 50���54, Pl. 7, figs. 55, 56, Pl. 8, figs. 57, 58, Pl. 9, figs. 59���61, Pl. 10, figs. 63���65, Pl. 11, figs. 66 ��� 62; Boesch, 1973: 230; Turbeville & Ruppert, 1983: 103; Fox & Ruppert, 1985: 37; Norenburg, 1993: 212; Hochberg & Lunianski, 1998: 295; Ritger & Norenburg, 2006: 941; Turbeville, 2006: 968, figs. 4, 5, 6 c; Chernyshev, 2010: 2288. Material examined. One specimen (26 mm), MZUSP 0 0 0 12, Brazil, Cear��, Paracuru, Praia da Pedra Rachada, 3 �� 23.95 ' S 39 �� 0.85 ' W, on mud sand, coll. Cecili Mendes, 16. VI. 2014. Field diagnosis. Body small, rounded anteriorly, flattened intestinal region; translucent, whitish anteriorly and yellowish-orange posteriorly. No eye spots, white dorsomedian line on head. Large mouth, immediately posterior to cerebral ganglia. Alimentary canal divided into two portions, anterior clear and less opaque than yellowish intestinal region, as seen by Coe (1905). Lateral organs present posterior to start of intestine; circular orange band formed in this region after preservation. Distribution. Western Atlantic: USA (Florida [Corr��a 1961], South Carolina [Fox & Ruppert 1985] and Virginia [Boesch 1973]) and Brazil (Cear�� [present study]) Eastern Pacific: USA (California [Coe, 1905]) Ecology. The present specimen was found in muddy sand, under rocks in the lower intertidal zone, which agrees with Coe (1905). However, Corr��a (1961) reports a specimen dredged from about 4 m in Biscayne Bay. Remarks. This species can be confused with Carinoma mutabilis because of the ground color, but C. mutabilis lacks lateral sense organs. Identification of the present specimens remains uncertain because there are few internal and external characters that can be compared with other species. A firmer identification awaits genetic study. A factor favouring the probability that this is conspecific with worms reported as C. lactea from Florida is the significant taxonomic overlap among nemerteans from Florida and Brazil. However, given the lack of morphological diagnostics, the identity for all Atlantic reports of this species must be held in doubt until compared with northeastern Pacific Ocean specimens from the vicinity of the type locale., Published as part of Mendes, Cecili B., Matthews-Cascon, Helena & Norenburg, Jon L., 2016, New records of ribbon worms (Nemertea) from Cear��, Northeast Brazil, pp. 146-156 in Zootaxa 4061 (2) on page 149, DOI: 10.11646/zootaxa.4061.2.4, http://zenodo.org/record/263586, {"references":["Coe, W. R. (1905) Nemerteans of the west and northwest coasts of America. Bulletin of the Museum of Comparative Zoology at Harvard College, 47, 1 - 318.","Boesch, D. F. (1973) Classification and community structure of macrobenthos in the Hampton Roads area, Virginia. Marine Biology, 21, 226 - 244. http: // dx. doi. org / 10.1007 / BF 00355253","Turbeville, J. M. & Ruppert, E. E. (1983) Epidermal muscles and peristaltic burrowing in Carinoma tremaphoros (Nemertini): correlates of effective burrowing without segmentation. Zoomorphology, 103, 103 - 120. http: // dx. doi. org / 10.1007 / BF 00312241","Fox, R. S. & Ruppert, E. E. (1985) Shallow-Water Marine Benthic Macroinvertebrates of South Carolina. Species Identification, Community Composition, and Symbiotic Associations. Belle W. Baruch Library in Marine Science No. 14. University of South Carolina Press, Columbia, SC, 43 pp.","Norenburg, J. L. (1993) Riserius pugetensis gen. n., sp. n. (Nemertina: Anopla), a new mesopsammic species, and comments on phylogenetics of some anoplan characters. Hydrobiologia, 266, 203 - 205. http: // dx. doi. org / 10.1007 / BF 00013369","Hochberg, F. G. & Lunianski, D. N. (1998) Nemertean collections at the Santa Barbara museum of Natural History: type specimens and vouchers for Wesley R. Coe's 1940 publication. Hydrobiologia, 365, 291 - 300. http: // dx. doi. org / 10.1023 / A: 1003178404193","Ritger, R. K. & Norenburg, J. L. (2006) Tubulanus riceae new species (Nemertea: Anopla: Palaeonemertea: Tubulanidae), from South Florida, Belize and Panama. Journal of Natural History, 40, 931 - 942. http: // dx. doi. org / 10.1080 / 00222930600833867","Turbeville, J. M. (2006) Ultrastructure of the pseudocnidae of the palaeonemerteans Cephalothrix cf. rufifrons and Carinomella lactea and an assessment of their phylogenetic utility. Journal of Natural History, 40 (15 - 16), 967 - 979. http: // dx. doi. org / 10.1080 / 00222930600834006","Chernyshev, A. V. (2010) Confocal laser scanning microscopy analysis of the phalloidin-labelled musculature in nemerteans. Journal of Natural History, 44, 37 - 40. http: // dx. doi. org / 10.1080 / 00222933.2010.504890","Kvist, S., Laumer, C. E., Junoy, J. & Giribet, G. (2014) New insights into the phylogeny, systematics and DNA barcoding of Nemertea. Invertebrate Systematics, 28, 287 - 308. http: // dx. doi. org / 10.1071 / IS 13061","Correa, D. D. (1961) Nemerteans from Florida and Virgin Islands. Bulletin of Marine Science of the Gulf and Caribbean, 11, 1 - 44."]}

Carinoma hamanako sp. nov., the ninth member of the genus, is described based on three specimens collected in Lake Hamana, Shizuoka Prefecture, Pacific coast of Honshu, Japan. The new species can be distinguished from its congeners by the blind-ending rhynchocoelic villar vessels, the lateral rhynchocoel vessels rejoining the lateral vessels, the unbranched excretory canals, the situation of the posterior part of the mid-dorsal nerve within the longitudinal muscle layer of the body wall, and the absence of a vascular plexus in the foregut region. A phylogenetic analysis based on the nuclear 28S rRNA and mitochondrial cytochrome c oxidase subunit I genes shows that C. hamanako sp. nov. forms a clade with two congeners, C. mutabile Griffin, 1898 and C. tremaphoros Thompson, 1900, thus supporting the generic placement of the new species.

The morphology of the rhynchocoel blood vessel was studied in 26 specimens representing 14 species of the family Cephalotrichidae. In eight specimens the vascular system could not be traced because of their small size, poor fixation, or contraction during fixation. In the other 18 specimens, a short mid-dorsal rhynchocoel vessel was found. In Cephalothrix adriatica, C. hongkongiensis, C. kefersteini, C. oestrymnica, C. orientalis, C. rufifrons, C. cf. fasciculus and C. cf. simula, the mid-dorsal rhynchocoel vessel penetrates the dorsal side of the proboscis insertion, and extends backward abutting the mid-dorsal rhynchocoel wall (Type A). In C. filiformis sensu Iwata (1954), the vessel is pendant in the rhynchocoel above the proboscis (Type B). In C. filiformis s.str., the vessel runs in the proboscis wall, after passing through the proboscis insertion (Type C). Morphology of the rhynchocoelic vessel might have taxonomic significance in cephalothrichids.

Callinera emiliae sp. nov., the ninth member of the genus, is described based on three specimens collected in Dumaguete, Negros Island, Republic of the Philippines. The new species can be distinguished from its congeners by the following characteristics: lateral sensory organs present; sub-epidermal glandular cells absent; blood vascular system without a ventral cephalic connective; nervous system with two dorsal cerebral commissures; and foregut nerves fused to form a ganglion in front of the mouth. In living specimens, epidermal constrictions were observed in the intestinal region; the presence of intestinal sphincters was confirmed in sectioned material and these correspond with the epidermal constrictions.

Based on specimens collected subtidally (similar to 10 m in depth) in Tomioka Bay, Japan, we describe the palaeonemertean Tubulanus tamias sp. nov., which differs from all its congeners in body coloration. In molecular phylogenetic analyses based on partial sequences of the nuclear 18S and 28S rRNA genes and histone H3, as well as the mitochondrial 16S rRNA and cytochrome c oxidase subunit I genes, among selected palaeonemerteans, T. tamias nested with part of the congeners in Tubulanus, while the genus as currently diagnosed appears to be non-monophyletic. Molecular cloning detected polymorphism in 28S rDNA sequences in a single individual of T. tamias, indicating incomplete concerted evolution of multiple copies. Tubulanus tamias is peculiar among tubulanids in having 9-10 pigment-cup eyes in the epidermis on either side of the head anterior to the cerebral sensory organs, and remarkably there are two types of eyes. The anterior 8-9 pairs of eyes, becoming larger from anterior to posterior, are completely embedded in the epidermis and proximally abutting the basement membrane; each pigment cup contains bundle of up to seven, rod-shaped structure that resemble a rhabdomeric photoreceptor cell. In contrast, the posterior-most pair of eyes, larger than most of the anterior ones, have an optical cavity filled with long cilia and opening to the exterior, thus appearing to have ciliary-type photoreceptor cells. The size and arrangement of the eyes indicate that the posterior-most pair of eyes are the remnant of the larval (or juvenile) eyes.

16 pages, 4 figures, 2 tables, A literature-based taxonomic catalogue of nemerteans (phylum Nemertea) from Spain and Portugal is provided, listing 75 species (12 Palaeonemertea, 24 Pilidiophora, and 39 Hoplonemertea) belonging to 34 genera. This is a low species number compared with the approximately 400 species listed in Europe. This lack of knowledge is mainly due to the low number of researchers interested in the phylum and the well-known taxonomic difficulties of its study. Geographic records are indicated for each species, and for some, comments are included on certain biological and taxonomic aspects, This research has benefited from funds from the Instituto de Estudios Ceutíes, Ceuta, Spain. The study was also supported by the Franklin Institute, Universidad de Alcalá

Specimens of Tubulanus riceae new species (Nemertea: Palaeonemertea) were collected from a Phragmatopoma worm reef in the surf zone at Fort Pierce (Florida, USA) and from sublittoral rubble at Carrie Bow Cay (Belize) and Bocas del Toro (Panama). They have well-developed lateral sensory organs, form a cellophane-like tube and appear to have ocelli-like structures. The latter, if confirmed as ocelli, would be the first reported for a tubulanid. The new species is characterized by a unique color pattern, resembling that of Tubulanus rhabdotus, but it is distinctive in its milky-tan ground color with annular bands of brown pigment bounded by white margins and in having up to six to eight dorsal, longitudinal, but broken, reflective white stripes.

Tetrodotoxin (TTX) was localized as brown color in different tissues of an undescribed species of the nemertean genus Cephalothrix (phylum Nemertea) and a turbellarian Planocera reticulata (phylum Platyhelminthes) on light microscopy by means of a monoclonal anti-TTX antibody. In the Cephalothrix sp., TTX was recognized in the vesicles apically arranged in the bacillary cells in the epidermis, basal lamina, the granular cells in the proboscis epithelium, rhynchocoel epithelium, and the vesicles in the basal portion of the intestinal wall near the blood vessels and rhynchocoel. The excretory system and the ovum also showed positive reaction of TTX antigen-antibody. On the other hand, the hermaphrodite flatworm P. reticulata exhibited TTX antigen-antibody complex only in their ovum. To our knowledge, this is the first experimental effort on micro-distribution of TTX in invertebrates.

The first description of the cleavage program of the palaeonemertean Carinoma tremaphoros (a member of a basal clade of the Nemertea) is illustrated by confocal microscopy and microinjection and compared to development of more derived nemerteans and other eutrochozoans (Annelida, Mollusca, Sipunculida and Echiurida). Lineage tracers were injected into individual blastomeres of C. tremaphoros at the 2-, 4-, 8- and 16-cell stage. Subsequent development was followed to the formation of simple (so-called planuliform) planktonic larvae to establish the ultimate fates of the blastomeres. Results of labeling experiments demonstrate that the development of C. tremaphoros bears closer similarity to other Eutrochozoa than development of a previously studied hoplonemertean (Nemertopsis bivittata) and a heteronemertean (Cerebratulus lacteus) in that the first cleavage plane bears an invariant relationship to the plane of bilateral symmetry of the larval body. Additionally, our cell-labeling experiments support the earlier suggestion that the transitory pre-oral belt of cells in the larvae of C. tremaphoros corresponds to the prototroch of other Eutrochozoa. A unique feature of development of C. tremaphoros includes the oblique orientation of the trochal lineages with respect to the anterior–posterior axis of the larva. The significance and application of cleavage characters such as presence of molluscan vs. annelid cross for phylogenetic analyses is reviewed. We argue that molluscan or annelid cross, neither of which are present in nemerteans, are merely two out of much greater variety of patterns created by the differences in the relative size and timing of formation of micromere quartets and none can be considered, by itself, as evidence of close phylogenetic relationship between phyla.

We present the most extensive phylogenetic analysis to date, to our knowledge, of higher-level nemertean relationships, based on sequence data from four different genes (the nuclear genes for nuclear large subunit rRNA (28S rRNA) and histone H3 (H3), and the mitochondrial genes for mitochondrial large subunit rRNA (16S rRNA) and cytochrome c oxidase subunit I (COI)). Well-supported clades are, in general, compatible with earlier, more limited, analyses, and current classification is largely in agreement with our results, although there are some notable exceptions. Bdellonemertea (represented by Malacobdella) is found to be a part of Monostilifera, and Polystilifera is the monophyletic sister group to Monostilifera. Cratenemertidae is the sister group to the remaining monostiliferans (including Malacobdella), a group to which we apply the new name Distromatonemertea. Heteronemertea is monophyletic and forms a clade with Hubrechtella; for this clade we introduce the name Pilidiophora. Finally, Pilidiophora and Hoplonemertea (with Malacobdella) form a monophyletic group, and we introduce the name Neonemertea to refer to this group. Palaeonemertea is found to be non-monophyletic and basal among nemerteans.

Nemerteans, a phylum of marine lophotrochozoan worms, have a biphasic life history with benthic adults and planktonic larvae. Nemertean larval development is traditionally categorized into direct and indirect. Indirect development via a long-lived planktotrophic pilidium larva is thought to have evolved in one clade of nemerteans, the Pilidiophora, from an ancestor with a uniformly ciliated planuliform larva. Planuliform larvae in a member of a basal nemertean group, the Palaeonemertea, have been previously shown to possess a vestigial prototroch, homologous to the primary larval ciliated band in the trochophores of other spiralian phyla, such as annelids and mollusks. We review literature on nemertean larval development, and include our own unpublished observations. We highlight recent discoveries of numerous pilidiophoran species with lecithotrophic larvae. Some of these larvae superficially resemble uniformly ciliated planuliform larvae of other nemerteans. Others possess one or two transverse ciliary bands, which superficially resemble the prototroch and telotroch of some spiralian trochophores. We also summarize accumulating evidence for planktotrophic feeding by larvae of the order Hoplonemertea, which until now were considered to be lecithotrophic. We suggest that 1) non-feeding pilidiophoran larval forms are derived from a feeding pilidium; 2) such forms have likely evolved many times independently within the Pilidiophora; 3) any resemblance of such larvae to the trochophores of other spiralians is a result of convergence and that 4) the possibility of planktotrophy in hoplonemertean larvae may influence estimates of pelagic larval duration, dispersal, and population connectivity in this group.

Background Maximally indirect development via a pilidium larva is unique to the pilidiophoran clade of phylum Nemertea. All other nemerteans have more or less direct development. The origin of pilidial development with disjunct invaginated juvenile rudiments and catastrophic metamorphosis remains poorly understood. While basal members of the phylum, the Palaeonemertea, do not appear to have ever had a pilidium, certain similarity exists in the development of the Pilidiophora and the sister clade, the Hoplonemertea. It is unclear whether this similarity represents the homology and whether pilidial development evolved before or after pilidiophorans diverged from hoplonemerteans. To gain insight into these questions, we examined the expression of Hox, Cdx, and Six3/6 genes in the development of the hoplonemertean Pantinonemertes californiensis and expression of Six3/6 in the pilidium of Micrura alaskensis. To further characterize the function of larval structures showing expression of these genes, we examined the serotonergic nervous system and cell proliferation in P. californiensis. Results We show that Hox and Cdx genes, which pattern the pilidial imaginal discs giving rise to the juvenile trunk, are expressed in paired posterior epidermal invaginations in P. californiensis larvae. We also show that Six3/6 patterns both the pilidial cephalic discs, which give rise to the juvenile head, and a pair of anterior epidermal invaginations in hoplonemertean development. We show that anterior invaginations in larval P. californiensis are associated with a pair of serotonergic neurons, and thus may have a role in the development of the juvenile nervous system. This is similar to the role of cephalic discs in pilidiophoran development. Finally, we show that four zones of high cell proliferation correspond to the paired invaginations in P. californiensis, suggesting that these invaginations may play a similar role in the development of the hoplonemertean juvenile to the role of imaginal discs in the pilidium, which also exhibit high rates of cell proliferation. Conclusions Expression of Hox, Cdx, and Six3/6 genes supports the homology between the imaginal discs of the pilidium and the paired larval invaginations in hoplonemerteans. This suggests that invaginated juvenile rudiments (possible precursors to pilidial imaginal discs) may have been present in the most recent common ancestor of the Pilidiophora and Hoplonemertea. Electronic supplementary material The online version of this article (doi:10.1186/s13227-015-0021-7) contains supplementary material, which is available to authorized users.

Nemerteans are predators of a wide variety of animals, but little is known of their role as prey for other animals. The presence of toxins in the tissues and secretions of these worms has led to the assumption usually suggested that they are ingested only rarely. However, analysis of a Food Habits Data Base from the United States National Marine Fisheries Service, compiled for fishes collected in the Atlantic Ocean from the Canadian border to Cape Hatteras, North Carolina (1973–1990), showed that nemerteans were recovered from the stomachs of 27 species of fishes in 14 families. They were found in 223 of 26 642 (0.84%) fish stomachs examined in the laboratory, but only in 0.09% of 58 812 fish examined in the field. Among species in the former category, for which ≥1000 were examined, the winter flounder, Pseudopleuronectes americanus(Walbaum), and the yellowtail flounder, Limanda ferruginea (Storer), had the greatest frequency of nemerteans, 71 of 1545 (4.6%) and 33 of 1045 (3.2%), respectively. These nemerteans were identified as Nemertea, Cerebratulus sp. or Micrura sp., but it is likely that they were all of a Cerebratulus-like type. Nemerteans have also been recorded from the guts of eight additional species (including four additional families) of fishes collected from the western Atlantic Ocean, Gulf of Mexico, eastern Pacific Ocean (Washington, Alaska), North Sea and Indian Ocean off South Africa. The black-bellied plover, Pluvialis squatarola(L.), semipalmated plover, Charadrius semipalmatus Bonapart and the herring gull, Larus argentatus Pontoppidan are the only three species known to feed on nemerteans (Cerebratulus lacteus (Leidy) and Paranemertes peregrina Coe by the black-bellied plover and C. lacteus by the other species). Several species of nemerteans are known to ingest other nemerteans, and several arthropods, a squid, and a few other invertebrates also feed on these worms. On the other hand, careful laboratory studies have shown that some members of the Palaeonemertea, Heteronemertea and Hoplonemertea, when fed to various species of fishes, crustaceans (Astacidea, Anomura, Brachyura and Amphipoda) and a polychaete, were rejected, usually violently. There is a history of using large nemerteans, e.g. Cerebratulus lacteus and Polybrachiorhynchus dayi, as bait by sport fishermen in the United States and South Africa. The incongruity of successfuly using these toxic animals to catch fish is discussed in relation to conclusions on the importance of nemerteans as prey in the marine environment.

We sequenced the complete mitochondrial genomes (mitogenomes) of three Hoplonemertea species, Amphiporus formidabilis, Prosadenoporus spectaculum and Nipponnemertes punctatula, which are 14,616, 14,655 and 15,354 bp in length, respectively. Each of the three circular mitogenomes consists of 37 typical genes and some non-coding regions. The nucleotide composition of the coding strand is biased toward T, almost a half of total nucleotides in these mitogenomes. There are many poly-T tracts across these mitogenomes, which exhibit T-number variation within different clones of protein-coding genes, mainly resulting from false PCR amplification. The major non-coding regions have tandem repeat motifs and hairpin-like structures that may be associated with the initiation of replication or transcription. Data published to date for nemerteans show that Palaeonemertea species usually bear the largest mitogenomes, while representatives in the more recently derived Distromatonemertea clade bear the smallest ones; and that the gene arrangement of mitogenomes seems to be variable within the phylum Nemertea, but stable within either of Heteronemertea and Hoplonemertea.

Names used for nemertean genera and species of the world are listed alpha-betically, with their original description citations, synonymy and current taxonomic status. Though many remain inadequately described, 250 genera and 1149 species are recognized as valid; these comprise Archinemertea (3 genera, 28 species), Palaeonemertea (11, 70), Heteronemertea (79, 401), monostiliferous Hoplonemertea (91, 500), reptantic polystiliferous Hoplonemertea (22, 45), pelagic polystiliferous Hoplonemertea (40, 97), Bdellonemertea (1, 5) and three monotypic genera whose higher taxonomic affinities are uncertain. In addition, three monotypic genera of fossil Nemertea are also listed. The higher systematic position and typical ecological habits of its species are shown for each valid genus, type-species are indicated, and brief details of species known habitats and distribution are noted.

In 1998, during a toxicological surveillance of various marine fouling organisms in Hiroshima Bay, Japan, specimens of the ribbon worm, Cephalothrix simula (Nemertea: Palaeonemertea) were found. These ribbon worms contained toxins with extremely strong paralytic activity. The maximum toxicity in terms of tetrodotoxin (TTX) was 25,590 mouse units (MU) per gram for the whole worm throughout the monitoring period. The main toxic component was isolated and recrystallized from an acidified methanolic solution. The crystalline with a specific toxicity of 3520 MU/mg was obtained and identified as TTX by high performance liquid chromatography (HPLC)-fluorescent detection (FLD) (HPLC-FLD), electrospray ionization-mass spectrometry (ESI-MS), infrared (IR), nuclear magnetic resonance (NMR) and gas chromatography-mass spectrometry (GC-MS). The highest toxicity of C. simula exceeded the human lethal dose per a single worm. A toxicological surveillance of C. simula from 1998 to 2005 indicated approximately 80% of the individuals were ranked as "strongly toxic" (≥1000 MU/g). Forty-eight percent of the specimens possessed toxicity scores of more than 2000 MU/g. Seasonal variations were observed in the lethal potency of C. simula. Specimens collected on January 13, 2000 to December 26, 2000 showed mean toxicities of 665-5300 MU/g (n = 10). These data prompted a toxicological surveillance of ribbon worms from other localities with different habitats in Japan, including Akkeshi Bay (Hokkaido) under stones on rocky intertidal beaches, as well as Otsuchi (Iwate) among calcareous tubes of serpulid polychaetes on rocky shores. Within twelve species of ribbon worms examined, only C. simula possessed extremely high toxicity. Therefore, C. simula appears to show generally high toxicity irrespective of their locality and habitat.

— A cladistic analysis based on 50 morphological characters was performed for 49 of the 98 species currently assigned to the subclass Palaeonemertea (phylum Nemertea), and six additional undescribed species. Thirty-five species were excluded from the parsimony analysis because of the high number of unknowns in the character matrix, and one species since it was considered a nomen nudum. An initial analysis suggested that the subclass Hoplonemertea is the sistergroup to the clade Palaeo- and Heteronemertea and the ingroup cladograms are rooted using a paraphyletic outgroup based on this information. Seventy-two equally most parsimonious cladograms were found; the consistency index was low but tree-length distribution for the character set is skewed to the left, and the cladograms are invariably shorter than trees based on random data. These cladograms suggested a character transformation series for the cerebral organ where this complex character reappeared several times after being absent. We considered this biologically implausible and the final discussion is based on three cladograms, one step longer than the most parsimonious, where the evolution of this character appears to be more realistic. The cladistic analysis indicates that many previously recognized genera (e.g. Cephalothrix, Procephalothrix and Cephalotrichella), and higher taxa, are paraphyletic. It furthermore indicates that the previously suggested hypothesis of the Archinemertea as a monophyletic sistertaxon to Palaeonemertea is unsupported.

A survey of the nemertean fauna along the Swedish west coast found specimens of 20 genera and 32 species, of which one genus and species is new to science (Tetraneuronemertes lovgreni gen. et sp. n.). The proportions of the three taxa Hoplonemertea, Heteronemertea, and Palaeonemertea are 34, 55, and 11%, respectively, with respect to specimen numbers, and the proportions for species within these taxa are 53, 31 and 16%, respectively. The most common species encountered during the survey were the heteronemerteans Lineus bilineatus, Micrura fasciolata, and Micrura purpurea, the hoplonemertean Nipponnemertes pulcher, and the palaeonemertean Cephalothrix rufifrons.

The mitochondrial genome sequences were determined for two species of nemerteans, Cephalothrix sp. (15,800 bp sequenced, near-complete) and Paranemertes cf. peregrina (14,558 bp, complete). As seen in most metazoans, the genomes encode 13 protein, 2 ribosomal RNA and 22 transfer RNA genes. The nucleotide composition is strongly biased toward A and T, as is typical for metazoan mtDNAs. There is also a significant strand skew in the distribution of these nucleotides, with the coding strand being richer in T than A and in G than C. All genes are transcribed in the same direction except for trnP and trnT, which is consistent with that reported for Cephalothrix hongkongiensis and Lineus viridis. Gene arrangement of Cephalothrix sp. is identical to that of C. hongkongiensis, while in P. cf. peregrina it is similar to L. viridis, but differs significantly from the three Cephalothrix species in the position of four protein-coding genes and seven tRNAs. Some protein-coding genes have 3′ end stem-loop structures, which may allow mRNA processing without flanking tRNAs. The major non-coding regions observed in the two genomes with potential to form stem-loop structures may be involved in the initiation of replication or transcription. The average Ka/Ks values, varying from 0.12 to 0.89, are markedly different among the 13 mitochondrial protein-coding genes, suggesting that there may exist different selective pressure among mitochondrial genes of nemerteans.

Callinera monensis sp. n., from Derbyhaven Harbour in the Islc of Man, is described and illustrated. The anatomy of the species is compared and contrasted with that of the other known members of the genus, Callinera buergeri Bcrgcndal and C. buergeri f. grandis Bergendal, from Scandinavian waters;f. grandis is afforded separate specific status as C. grandis Bcrgcndal.

Sundberg, Per, Chernyshev, Alexey. V., Kajihara, Hiroshi, Kånneby, Tobias, Strand, Malin (2009): Character-matrix based descriptions of two new nemertean (Nemertea) species. Zoological Journal of the Linnean Society 157 (2): 264-294, DOI: 10.1111/j.1096-3642.2008.00514.x, URL: https://academic.oup.com/zoolinnean/article-lookup/doi/10.1111/j.1096-3642.2008.00514.x

A continuous 10.1kb fragment of the Cephalothrix rufifrons (Nemertea, Palaeonemertea) mitochondrial genome was sequenced and characterized to further assess organization of protostome mitochondrial genomes and evaluate the phylogenetic potential of gene arrangement and amino acid characters. The genome is A-T rich (72%), and this biased base composition is partly reflected in codon usage. Inferred tRNA secondary structures are typical of those reported for other metazoan mitochondrial DNAs. The arrangement of the 26 genes contained in the fragment exhibits marked similarity to those of many protostome taxa, most notably molluscs with highly conserved arrangements and a phoronid. Separate and simultaneous phylogenetic analyses of inferred amino acid sequences and gene adjacencies place the nemertean within the protostomes among coelomate lophotrochozoan taxa, but do not find a well-supported sister taxon link.

Kajihara, Hiroshi (2006): Four palaeonemerteans (Nemertea: Anopla) from a tidal flat in middle Honshu, Japan. Zootaxa 1163: 1-47, DOI: 10.5281/zenodo.2645302, {"references":["Bergendal, D. (1900a) Studier ofver nemertiner. I. Callinera burgeri Bergendal, en representant for ett afvikande slagte bland Palaonemertinerna. Lunds Universitets Arsskrift, 36, 1-47.","Bergendal, D. (1900b) Till kannedomen om de nordiska Nemertinerna. Ofversigt af Kongliga Vetenskaps-Akademiens Forhandlingar, 57, 581-602.","Bergendal, D. (1900c) Uber ein Paar sehr eigenthumliche nordische Nemertinen. Zoologischer Anzeiger, 23, 313-328.","Bergendal, D. (1901) Studier ofver nemertiner. I. Callinera burgeri Bergendal, en representant for ett afvikande slagte bland Palaonemertinerna. Lunds Universitets Arsskrift, 37, 49-116.","Bergendal, D. (1902a) Zur Kenntnis der nordischen Nemertinen. 2. Eine der construierten Urnemertine entsprechende Palaeonemerine aus dem Meere der schwedischen Westkuste. 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We estimated the phylogenetic relationships of 15 nemertean (phylum Nemertea) species from the four subclasses Hoplo-, Hetero-, Palaeo-, and Bdellonemertea with 18S rDNA sequence data. Three outgroup taxa were used for rooting: Annelida, Platyhelminthes, and Mollusca. Parsimony and maximum-likelihood analyses supported the monophyletic status of the Heteronemertea and a taxon consisting of hoplonemerteans and Bdellonemertea, while indicating that Palaeonemertea is paraphyletic. The monophyletic status of the two nemertean classes Anopla and Enopla is not supported by the data. The unambiguous clades are well supported, as assessed by a randomization test (bootstrapping) and branch support values.