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Lineus ruber (Müller, 1774) and Lineus viridis (Müller, 1774) are among the longest known and most abundant intertidal nemertean species found on both sides of the North Atlantic. Due to easy maintenance in captivity, both species have been well studied concerning morphology , reproduction, development and ecology. Originally described as two separate species in the 18th century, they were subsequently synonymised and considered colour varieties of a single species. It was not until the mid-20th century that complementary redescriptions, including information on reproduction and development, re-established the specific identities of L. ruber and L. viridis. With the advent of molecular markers in nemer-tean systematics, however, doubt was again cast on their specific identities. To solve one of the longest standing problems in nemertean systematics, we assembled a comprehensive data set combining external morphology and three genetic markers (mitochondrial cytochrome c oxidase subunit I, 16S rRNA and nuclear internal transcribed spacer region) from 160 specimens of L. ruber and L. viridis collected at six sampling sites along the continental coast of Western Europe. The data set was analysed with tree-based and non-tree-based species delimitation methods. The results from all methods used confidently delimit three separate clades. A distinct barcoding gap was detected in our data set which thus provides a framework to unequivocally identify specimens as members of any of the three species. Comparison of our findings with published data enables us to assign one lineage to L. ruber and one to L. viridis. We designated neotypes for both species. The third clade is very similar to L. viridis, only distinguishable by a conspicuous, iridescent ventral fold in some male specimens This lineage shows a syntopic distribution along western European coasts and represents a species new to science and is described as Lineus clandestinus sp. n. based on its external characters and the analyses of the molecular data provided in this study.
Although some clades of ribbon worms (phylum Nemertea) are consistently recovered with high support in molecular phylogenies, the placement and interrelationships of some taxa have proven problematic. Herein, we performed molecular phylogenetic analyses aimed at resolving these recalcitrant splits, using six loci (nuclear 18S rRNA, 28S rRNA, histones H3 and H4, and mitochondrial 16S rRNA and COI) for 133 terminals, with particular emphasis on the problematic families Hubrechtidae and Plectonemertidae. Three different datasets were used for phylogenetic analyses and both maximum likelihood and maximum parsimony methodologies were applied. All but one of the resulting tree topologies agree on the paraphyly of the class Palaeonemertea, whereas Heteronemertea, Hoplonemertea, Polystilifera, Monostilifera and Hubrechtidae are always recovered as reciprocally monophyletic. Hubrechtidae is sister group to Heteronemertea (the Pilidiophora hypothesis) only when length variable regions of 18S rRNA and 28S rRNA are excluded. Moreover, the terrestrial and freshwater family Plectonemertidae is recovered with high support and the implications of this finding are further discussed. Finally, we evaluate the utility of DNA barcoding for specimen identification within Nemertea using an extended dataset containing 394 COI sequences. Results suggest that DNA barcoding may work for Nemertea, insofar as a distinct barcoding gap (the gap between the maximum intraspecific variation and the minimum interspecific divergence) may exist, but its recognition is regularly hampered by low accuracy in species level identifications.
2012 •
Hydrobiologia
Phylogeny of Nemertea with special interest in the placement of diversity from Far East Russia and northeast Asia2015 •
In recent years the Norwegian Taxonomy Initiative started thorough investigations of poorly known organism groups. In this context, several marine inventories have rendered a number of marine invertebrate species new to science. Within the phylum Nemertea (ribbon worms) a characteristic hoplonemertean was encountered on two different occasions. We describe the new species Amphiporus rectangulus sp. nov. with a combination of histology and DNA data (COI). For the morphological description we use a previously proposed character matrix and, in a context given by the results, also provide a brief discussion on benefits and drawbacks with both methods. We argue that for small animals with soft bodies external characters can be more informative than hitherto expected.
The heteronemertean species Micrura dellechiajei is thus far only known from its type locality in the Gulf of Naples (Italy) and has not been recorded in 120 years. During two oceanographic surveys conducted in Spanish Mediterranean waters, several nemertean specimens were collected, and thorough morphological examination indicated that some of these pertained to the species M. dellechiajei, suggesting that populations may be more widespread than previously thought. Because of the rarity of this species coupled with the fact that its last morphological narrative was given 120 years ago, we here provide a redescription of the species based on the new specimens, complete with illustrations and new data concerning its morphology, and we also place some of the collected specimens in a molecular phylogenetic framework.
The difficulty in the sampling, processing and identification (mainly based on histological methods) of nemerteans has derived in a clear underestimation of their biodiversity. Within the phylum, Palaeonemertea often lacks of external morphological discriminant characters, so that an anatomical analysis is usually essential. Identification of one of these groups –Cephalotrichidae, monotypic family integrated by 36 species of the genus Cephalothrix– is based in very subtle and of hard interpretation characters. The previous bibliography is confusing in several descriptions. Nevertheless, this genus is the best represented in the cytochrome oxidase I databases, and thus DNA barcoding studies can be used in assessing its biodiversity in a determinate geographic area, such as the Iberian Peninsula. In the present work, molecular and morphological studies have being carried out on four Iberian Cephalothrix species. Cephalothrix filiformis does not match any of the sequences assigned to this species in the previous literature, but morphological identification of the Iberian material is correct. For this reason, the sequences of the present work are considered the correct barcodes for this species. Cephalothrix sp. A is the sister species of C. rufifrons, although histological studies must be carried out for determining its taxonomic status. Cephalothrix sp. B may constitute a new species with an amphiatlantic distribution, although histological studies are needed for its formal description. Finally, the specimens of one of the species have been morphologically and molecularly identified as C. fasciculus, a Northern Pacific species, constituting the first record of a biological invasion by a marine nemertean species. All these data confirm that DNA barcoding is an appropriate method for a first approximation to the real biodiversity of a taxonomic group for a given geographic area. Although it is the best molecular studied group, 80% of the sequenced species correspond to undescribed or misidentified species. For this reason, a series of recommendations is proposed for the study of the biodiversity of this genus based on morphological and molecular features.
Of 45 species of nemerteans reported for the Brazilian coast, only two were recorded from Brazil’s Northeast coast. Here we report seven new records for the state of Ceará, in Northeast Brazil: Tubulanus rhabdotus Côrrea, 1954, Carinomella cf. lactea Coe, 1905, Baseodiscus delineatus (Delle-Chiaje 1825), Cerebratulus cf. lineolatus Coe, 1905, Cerebratulus sp. 1, Cerebratulus sp. 2 and Lineidae sp. 1. Specimens were collected at the following beaches: Praia dos Dois Coqueiros, Praia do Pacheco, Pecém harbor, Praia da Pedra Rachada and Praia do Guajiru. T. rhabdotus is a new record for Northeast Brazil, Carinomella cf. lactea and Cerebratulus cf. lineolatus are new records for the South Atlantic Ocean and both genera are new records for Brazil.
2014 •
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.
Journal of Natural History
Comparative morphology and evolution of the nephridia in Nemertea2010 •
Molecular biology and evolution
A transcriptomic approach to ribbon worm systematics (nemertea): resolving the pilidiophora problem2014 •
2012 •
Zoological journal of the …
A new genus and species of monostiliferoidean nemertean (Nemertea: Enopla) found on an egg mass of the anomuran decapod Paralithodes camtschatica1990 •
2013 •
Proceedings of the Royal Society B: Biological Sciences
Ribbon worm relationships: a phylogeny of the phylum Nemertea2003 •
Journal of Morphology
Comparative sperm ultrastructure in Nemertea2010 •
Helgoland Marine Research
Life history of Lineus viridis (Müller, 1774) (Heteronemertea, Nemertea)2012 •
Marine Biology
Worms without borders: genetic diversity patterns in four Brazilian Ototyphlonemertes species (Nemertea, Hoplonemertea)2011 •
2013 •
2009 •
Proyectos de Investigación en …
Los nemertinos del Parque Nacional marítimo-terrestre de las Islas Atlánticas de Galicia2006 •
Marine Biodiversity Records
First record of the poorly known pelagic nemertean Protopelagonemertes beebei (Nemertea: Hoplonemertea: Polystilifera: Pelagica) from Japanese waters, with discussion of the species identity2011 •
Molecular Biology and Evolution
Platyzoan Paraphyly Based on Phylogenomic Data Supports a Noncoelomate Ancestry of Spiralia2014 •
2014 •
Zoologica Scripta
Phylogenetic analysis of a group of palaeonemerteans (Nemertea) including two new species from Queensland and the Great Barrier Reef, Australia2003 •
2001 •
Organisms Diversity & Evolution
Higher-level metazoan relationships: recent progress and remaining questions2011 •
Zoologica Scripta
Phylogenetic position of Nerillidae and Aberranta (Polychaeta, Annelida), analysed by direct optimization of combined molecular and morphological data2005 •
2001 •
2008 •
Polish Polar Research
Oligodendrorhynchus hesperides gen. et sp. n. (Heteronemertea) from the Bellingshausen Sea2000 •
Revista Brasileira de Zoologia
Polychaeta, Annelida, and Articulata are not monophyletic: articulating the Metameria (Metazoa, Coelomata)2003 •