Long forgotten: Eunice woodwardi Baird, 1869 (Annelida, Eunicidae) revisited, with an insight on internal anatomy.

Eunice woodwardiBaird, 1869, originally described from the Ría de A Coruña (NW Iberian Peninsula), has been overlooked and never reported from the Atlantic coast of Spain after original description and the subsequent redescription of the holotype. In the present study, we revised comparatively the holotype, newly collected specimens of this species and specimens identified as Eunice vittata (Delle Chiaje, 1829) from western Mediterranean Sea. The validity of E. woodwardi is supported and previous descriptions are complemented after a throughout study of the external morphology by means of light compound microscopy and scanning electron microscopy, and that of the internal anatomy by histological sectioning and micro-computed tomography. The presence of eyes, nuchal organs, dorsal and ventral ciliary organs on parapodial cirri and paired nephridia in most segments is confirmed in E. woodwardi; the digestive tract is clearly regionalized and divided into pharynx, oesophagus, stomach, fore, mid- and hind intestine. The presence of E. woodwardi in the Ría de Ferrol is also reported, and we suggest that previous records of E. vittata in NW Iberian Peninsula should be reviewed. Eunice woodwardi is distinguished by a set of characters such as having non-articulated and non-constricted cephalic appendages, the maxillary formula, the range of branchial distribution, maximum number of branchial filaments, number of limbate and compound falciger chaetae per parapodium, the presence of an apical mucro in the guard of falciger chaetae blades and the number of teeth in pectinate chaetae. Epibiont Ciliophora on branchiae are also reported.

A further step towards the characterisation of Terebellides (Annelida, Trichobranchidae) diversity in the Northeast Atlantic, with the description of a new species.

Several new species of genus Terebellides Sars, 1835 (Annelida, Trichobranchidae) have been recently described from the Northeast Atlantic Ocean after the detection of a large complex of species based on DNA sequence data from previous research. Some of those species (belonging to the so-called Group A) have already been described elsewhere. In this paper, we revise several Terebellides clades belonging to Groups B, C and D resulting in the identification of five nominal species: Terebellidesgracilis Malm, 1874, Terebellidesatlantis Williams, 1984, Terebellideswilliamsae Jirkov, 1989, Terebellidesirinae Gagaev, 2009, and Terebellidesshetlandica Parapar, Moreira & O'Reilly, 2016, plus one new species described here as Terebellideslavesquei sp. nov. All these species are characterised by a combination of morphological features complemented with a nucleotide diagnostic approach (specific COI nucleotides in the alignment position). Morphological characters used to discriminate between taxa refer to the branchial shape, presence/absence of ciliated papillae dorsal to thoracic notopodia and the morphology of thoracic and abdominal uncinal teeth. An updated identification key to all described species of this genus in NE Atlantic waters is also included.

A new species of Polyophthalmus (Annelida, Opheliidae) from the Arabian Gulf, with an insight on internal anatomy and diversity of the genus.

Polyophthalmus zhadanae sp. nov. (Annelida, Opheliidae), is described from the coast of Kuwait and Saudi Arabia (Arabian Gulf) after specimens collected in the intertidal and shallow subtidal. This new species is characterised by the body pigmentation pattern, distribution of lateral eyes, presence of small dorsal and ventral parapodial cirri and pygidial features. External and internal anatomy was described after examination with SEM and micro-CT. The presence of several body structures in the genus such as a cephalic palpode-like papilla is discussed. Furthermore, the diversity of genus Polyophthalmus and the presence of Polyophthalmus pictus (Dujardin, 1839) in the Indo-Pacific is reviewed and a key to species is provided.

To name but a few: descriptions of five new species of Terebellides (Annelida, Trichobranchidae) from the North East Atlantic.

The number of described species of the genus Terebellides Sars, 1835 (Annelida, Trichobranchidae) has greatly increased in the last years, particularly in the North East Atlantic. In this context, this paper deals with several putative species recently delineated by molecular means within a well delimited clade of Terebellides. Species are characterised here by a combination of morphological characters, and a complementary nucleotide diagnostic approach. Three species were identified as the nominal species T. stroemii Sars, 1835, T. bigeniculatus Parapar, Moreira & Helgason, 2011 and T. europaeaLavesque et al., 2019. Five species are described as new: T. bakkeni sp. nov., T. kongsrudi sp. nov., T. norvegica sp. nov., T. ronningae sp. nov. and T. scotica sp. nov. The distinctive morphological characters refer to the branchial shape, absence or presence of papillae on lamellae of anterior margin of branchial dorsal lobes, absence or presence of ciliated papillae dorsal to thoracic notopodia, geniculate chaetae in one or two chaetigers, and the morphology of thoracic and abdominal uncini teeth. Furthermore, the description of T. bigeniculatus is revised and complemented after examination of type specimens. An updated identification key to all species of the genus in NE Atlantic and a proposal of a classification of different types of abdominal uncini to be used in taxonomy are also included.

On the diversity of Terebellides (Annelida, Trichobranchidae) in West Africa, seven new species and the redescription of T. africana Augener, 1918 stat. prom.

The actual diversity of Terebellides (Annelida; Trichobranchidae) in the South East Atlantic Ocean remains largely unknown. Only two species have been reported to date, T. stroemii Sars, 1835 and T. jorgeni Hutchings, 2007. The revision of specimens collected during the Atlantide and Galathea oceanographic cruises in the Atlantic coast of Africa, along with new materials obtained during monitoring surveys off Gabon, Congo and Angola, has allowed us to describe seven new species: T. augeneri sp. nov., T. congolana sp. nov., T. fauveli sp. nov., T. kirkegaardi sp. nov., T. longiseta sp. nov., T. nkossa sp. nov. and T. ramili sp. nov. Moreover, the type material of Terebellides stroemii var. africana Augener, 1918 is redescribed and the variety raised to species. All taxa are morphologically characterised and compared with species described or reported in world seas, particularly from the Atlantic Ocean. The presence of T. stroemii in Africa and the validity of the thoracic uncini as taxonomic character is discussed and a key to all species of Terebellides described from the South Atlantic Ocean is provided.

Validation of Owenia vieitezi Díaz-Díaz, Parapar amp; Moreira, a polychaete from the coast of Venezuela (Annelida: Oweniidae).

Díaz-Díaz et al. (2018) described a new species of oweniid polychaete, Owenia vieitezi, from the north-western coast of the Gulf of Venezuela, Caribbean Sea. Although the description and figures presented by Díaz-Díaz et al. (2018) fully characterize the new species, the journal issue in which the description appeared was published online only and the article in which the new name appeared did not include a ZooBank registration number (LSID), required for validation of new species names in electronic-only publications (ICZN 2012). As a result, the name Owenia vieitezi Díaz-Díaz, Parapar Moreira, 2018, as published in Cahiers de Biologie Marine 59: 589-597, is not available according the International Code of Zoological Nomenclature (ICZN 1999, 2012). Therefore, the present note serves to validate the name Owenia vieitezi by fulfilling the ICZN conditions for nomenclatural availability.

An integrative approach to the anatomy of Syllis gracilis Grube, 1840 (Annelida) using micro-computed X-ray tomography.

BACKGROUND: The overall anatomy of the genus Syllis (Annelida: Syllidae) has been largely studied; however, an integrative approach considering different anatomical techniques has never been considered. Here, we use micro-computed X-ray tomography (micro-CT) to examine the internal anatomy of Syllis gracilis Grube, 1840, along with other widely available techniques. METHODS: We studied the anatomy of the marine annelid S. gracilis through an integrative approach, including micro-CT along with stereo and light compound microscopy (STM, LCM), scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM) and histological sectioning (HIS). In this manner, we evaluated the applicability of micro-CT for the examination of annelid anatomy by testing whether the images obtained make it possible to visualize the main body structures, in comparison with other current techniques, of the various elements of its internal anatomy. RESULTS: Overall external and internal body elements are clearly shown by the integrative use of all techniques, thus overcoming the limitations of each when studied separately.Any given method shows disparate results, depending on the body part considered. For instance, micro-CT provided good images of the external anatomy, including relevant characters such as the shape, length and number of articles of dorsal parapodial cirri. However, it is especially useful for the examination of internal anatomy, thus allowing for 3D visualization of the natural spatial arrangement of the different organs. The features best visualized are those of higher tissue density (i.e., body musculature, anterior parts of the digestive tract), particularly in 3D images of unstained specimens, whereas less electrodense tissues (i.e., the peritoneal lining of septa and nervous system) are less clearly visualized. The use of iodine stain with micro-CT has shown advantages against non-staining for the adequate observation of delicate elements of low density, such as the segmental organs, the connective between the ganglia, the ventral nerve cord and segmental nerves. DISCUSSION: Main external anatomical elements of S. gracilis are well shown with micro-CT, but images show lesser optical resolution and contrast when compared to micrographs provided by SEM and CLSM, especially for fine structural features of chaetae. Comparison of micro-CT and HIS images revealed the utility and reliability of the former to show the presence, shape and spatial disposition of most internal body organs; the resolution of micro-CT images at a cellular level is, however, much lower than that of HIS, which makes both techniques complementary.

Systematic re-structure and new species of Sphaerodoridae (Annelida) after morphological revision and molecular phylogenetic analyses of the North East Atlantic fauna.

Detailed morphological study of more than 2600 North East Atlantic (NEA) sphaerodorids (SphaerodoridaeAnnelida) and phylogenetic analyses of DNA sequences of representatives of several identified morphospecies enforced changing the current systematic classification within the family allowed the discovery of new species provided new information about the morphological and genetic characterisation of members of this group and increased the species occurrence data to better infer their geographic and bathymetric distribution ranges. Phylogenetic analyses of nuclear (18S rRNA and 28S rRNA) and mitochondrial sequences (COI and 16S rRNA) of NEA short-bodied sphaerodorids revealed outstanding results including paraphyly of the genera Sphaerodoropsis Sphaerodoridium, and Sphaerephesia. The number of longitudinal and transverse rows of dorsal macrotubercles is proposed as potential synapomorphies for the main clades and are consequently herein used for the genera delimitation. The new classification proposed here implies nomenclatural changes and the erection of a new genus Geminofilum gen. n. to accommodate the species previously considered as Sphaerodoropsis with two transverse rows of dorsal macrotubercles per segment. Four species are being described herein: Euritmianordica Capa & Bakken sp. n. Sphaerephesiamultichaeta Capa Moreira & Parapar sp. n. Sphaerephesiaponsi Capa Parapar & Moreira sp. n. and Sphaerodoridiumceliae Moreira Capa & Parapar sp. n. Characterisation of the other 21 species including updated iconography and an identification key to all NEA short-bodied sphaerodorids are provided.

Morphological, cellular and molecular characterization of posterior regeneration in the marine annelid Platynereis dumerilii.

Regeneration, the ability to restore body parts after an injury or an amputation, is a widespread but highly variable and complex phenomenon in animals. While having fascinated scientists for centuries, fundamental questions about the cellular basis of animal regeneration as well as its evolutionary history remain largely unanswered. Here, we present a study of regeneration of the marine annelid Platynereis dumerilii, an emerging comparative developmental biology model, which, like many other annelids, displays important regenerative abilities. When P. dumerilii worms are amputated, they are able to regenerate the posteriormost differentiated part of their body and a stem cell-rich growth zone that allows the production of new segments replacing the amputated ones. We show that posterior regeneration is a rapid process that follows a well reproducible path and timeline, going through specific stages that we thoroughly defined. Wound healing is achieved one day after amputation and a regeneration blastema forms one day later. At this time point, some tissue specification already occurs, and a functional posterior growth zone is re-established as early as three days after amputation. Regeneration timing is only influenced, in a minor manner, by worm size. Comparable regenerative abilities are found for amputations performed at different positions along the antero-posterior axis of the worm, except when amputation planes are very close to the pharynx. Regenerative abilities persist upon repeated amputations without important alterations of the process. We also show that intense cell proliferation occurs during regeneration and that cell divisions are required for regeneration to proceed normally. Finally, 5-ethynyl-2'-deoxyuridine (EdU) pulse and chase experiments suggest that blastemal cells mostly derive from the segment immediately abutting the amputation plane. The detailed characterization of P. dumerilii posterior body regeneration presented in this article provides the foundation for future mechanistic and comparative studies of regeneration in this species.

A mega-cryptic species complex hidden among one of the most common annelids in the North East Atlantic.

We investigate mitochondrial (COI, 16S rDNA) and nuclear (ITS2, 28S rDNA) genetic structure of North East Atlantic lineages of Terebellides, a genus of sedentary annelids mainly inhabiting continental shelf and slope sediments. We demonstrate the presence of more than 25 species of which only seven are formally described. Species boundaries are determined with molecular data using a broad range of analytical methods. Many of the new species are common and wide spread, and the majority of the species are found in sympatry with several other species in the complex. Being one of the most regularly encountered annelid taxa in the North East Atlantic, it is more likely to find an undescribed species of Terebellides than a described one.

On the diversity of the SE Indo-Pacific species of Terebellides (Annelida; Trichobranchidae), with the description of a new species.

The study of material collected during routine monitoring surveys dealing with oil extraction and aquaculture in waters off Myanmar (North Andaman Sea) and in the Gulf of Thailand, respectively, allowed us to analyse the taxonomy and diversity of the polychaete genus Terebellides (Annelida). Three species were found, namely Terebellides cf. woolawa, Terebellides hutchingsae spec. nov. (a new species fully described and illustrated), and Terebellides sp. (likely a new species, but with only one available specimen). The new species is characterised by the combination of some branchial (number, fusion and relative length of lobes and papillation of lamellae), and thoracic (lateral lobes and relative length of notopodia) characters and is compared with all species described or reported in the SW Indo-Pacific area, as well as with those sharing similar morphological characteristics all around the world. The taxonomic relevance of the relative length of branchial lobes and different types of ciliature in branchial lamellae for species discrimination in the genus is discussed. A key to all Terebellides species described in SE Indo-Pacific waters is presented.

A new species of the genus Terebellides (Polychaeta, Trichobranchidae) from the Iranian coast.

Based on specimens collected during several sampling programmes along the Iranian coast, Persian Gulf, a new species of the genus Terebellides (Polychaeta, Trichobranchidae) is herein described as Terebellides persiae spec. nov. The new species is primarily characterised by the presence of a large dorsal thoracic hump in larger specimens and ciliated papillae on the branchial lamellae. The new species is compared with other taxa belonging to Terebellides described or reported with any of both characters. SEM and micro-CT have been used to study T. persiae spec. nov. and provide several new details on external characters and internal organs, respectively. A key for the identification of the species of Terebellides with dorsal hump is provided.

First record of genus Orbiniella Day, 1954 (Polychaeta: Orbiniidae) in North Atlantic Ocean with the description of a new species.

A new species of the genus Orbiniella Day, 1954 (Polychaeta: Orbiniidae), collected during the BIOICE programme on sedimentary bottoms off Iceland, is described. Orbiniella petersenae sp. nov. is a shelf and slope species (107 to 1,915 m) chiefly characterized by having notopodial postchaetal papilla from first chaetiger, long crenulated capillary chaetae and several acicular chaetae on each parapodial rami, and pygidium with four lobes. External micromorphology and gross internal anatomy were studied using, respectively, SEM and micro-CT; this is the first time these techniques are used for any species in this genus. A key to all species of this genus worldwide is provided.

Six new species of the genus Armandia Filippi, 1861 (Polychaeta, Opheliidae) from Lizard Island (Great Barrier Reef, Australia).

From the study of the material collected during the Polychaete Workshop held in Lizard Island (Great Barrier Reef, Australia) in August 2013, six species belonging to the genus Armandia (Polychaeta, Opheliidae) are newly described. Armandia bifida n. sp. is characterised by the bifid shape of the prechaetal lobe in CH1-CH3, A. dolio n. sp. by the barrel-shaped anal (=pygidial) tube (=funnel), A. filibranchia n. sp. by the extremely long and thin branchiae, A. laminosa n. sp. by the foliose shape and large size of the prechaetal lobe in CH1-CH3, A. paraintermedia n. sp. by the squared-shaped anal tube and size and shape of anal cirri, and A. tubulata n. sp. by the tubular shape of the anal tube. All species are fully described and illustrated, and compared with similar species. Several body characters of taxonomic relevance (e.g., anal tube and parapodia shape) are studied based on SEM micrographs. A key of the Armandia species hitherto described or reported in South-East Asia and Australasia is provided based on features of the anal tube.

The Oweniidae (Annelida; Polychaeta) from Lizard Island (Great Barrier Reef, Australia) with the description of two new species of Owenia Delle Chiaje, 1844.

Study of the Oweniidae specimens (Annelida; Polychaeta) from Lizard Island (Great Barrier Reef, Australia) stored at the Australian Museum, Sydney and newly collected in August 2013 revealed the presence of three species, namely Galathowenia quelis Capa et al., 2012 and two new species belonging to the genus Owenia Delle Chiaje, 1844. Owenia dichotoma n. sp. is characterised by a very short branchial crown of about 1/3 of thoracic length which bears short, dichotomously-branched tentacles provided with the major division close to the base of the crown. Owenia picta n. sp. is characterised by a long branchial crown of about 4/5 of thoracic length provided with no major divisions, ventral pigmentation on thorax and the presence of deep ventro-lateral groove on the first thoracic chaetiger. A key of Owenia species hitherto described or reported in South East Asia and Australasia regions is provided based on characters of the branchial crown.

A new species of Sphaerodoridium Lützen, 1961 from Iceland (Polychaeta: Sphaerodoridae).

A new species of Sphaerodoridium Lützen, 1961 (Polychaeta: Sphaerodoridae) collected off Iceland during the BIOICE programme is described. Sphaerodoridium guerritai sp. nov. is mostly present in waters around the northern half of Iceland, and seems to be common in soft bottoms at depths of 49-1253 m. It is mainly characterized by having macrotubercles which are provided with a long stalk which bears 1-3 small papillae; this seems an unique feature in Sphaerodoridium and the closely related genus Clavodorum Hartman and Fauchald, 1971. Furthermore, the new species is also characterized by having one transversal row of 11-12 dorsal macrotubercles per chaetiger in midbody; 10-16 spherical papillae in front of each row of macrotubercles, somewhat arranged in a dorsal zig-zag; 10-18 ventral papillae per chaetiger arranged following a non-random pattern: two transversal rows on parapodial areas and one on interparapodial area, of usually 4, 6 and 5 papillae respectively. Short paired tubular structures with distal opening were found on the ventrum of most chaetigers and are interpreted as nephridial papillae and nephridiopores, respectively. Females show special ventral structures between chaetigers 9-10 which may represent genital openings as suggested for other sphaerodorids; males do not show any apparent copulatory structures. A comprehensive table comparing some diagnostic features regarding macrotubercles and body papillae of all known species of Sphaerodoridium and Clavodorum is provided. 

Diversity of the genus Terebellides (Polychaeta: Trichobranchidae) in the Adriatic Sea with the description of a new species.

Based on specimens collected during the sampling campaigns in the Northern Adriatic from 2003-2010, the diversity of genus Terebellides (Polychaeta; Trichobranchidae) was studied and three species are reported for the Northern Adriatic Sea: Terebellides gracilis Malm, 1874, Terebellides mediterranea spec. nov., and Terebellides stroemii Sars, 1835. Terebellides stroemii was the only species previously reported from the area. Terebellides gracilis is reported for the first time for the Mediterranean Sea and its geographical distribution is extended south. Terebellides mediterranea spec. nov., is characterised by the presence of long notopodia and notochaetae in the first thoracic chaetiger. These three species are compared to other Terebellides species described or reported from North Atlantic waters, and a key to Terebellides species of the North East Atlantic and Mediterranean is provided.