A phylogenetic analysis of the genus Eunice (Eunicidae, polychaete, Annelida)

Species of Eunice are distributed worldwide, inhabiting soft and hard marine bottoms. Some of these species play significant roles in coral reef communities and others are commercially important. Eunice is the largest and most poorly defined genus in Eunicidae. It has traditionally been subdivided in taxonomically informal groups based on the colour and dentition of subacicular hooks, and branchial distribution. The monophyly of Eunice and of its informal subgroups is tested here using cladistic analyses of 24 ingroup species based on morphological data. In the phylogenetic hypothesis resulting from the present analyses Eunice and its subgroups are paraphyletic; the genus may be divided in at least two monophyletic groups, Eunice s.s. and Leodice , but several species do not fall inside these two groups. Most of the traditional characters used in the taxonomy of Eunice are homoplasies; however, characters used for the first time in this study, such as certain jaw characters and characters derived from a close examination of chaetal variation along the body, are promising sources of phylogenetic signal.  © 2007 The Linnean Society of London, Zoological Journal of the Linnean Society , 2007, 150 , 413–434.     

New insights into polychaete phylogeny (Annelida) inferred from 18S rDNA sequences

Annelid systematics and the ingroup relationships of polychaete annelids are matter of ongoing debates in recent analyses. For the investigation of sedentary polychaete relationships a molecular phylogenetic analysis was conducted based on 94 sequences of 18S rDNA, including unpublished sequences of 13 polychaete species. The data set was analyzed with maximum parsimony and maximum likelihood methods, as wells as Bayesian inference. As in previous molecular analyses the monophyly of many traditional polychaete families is confirmed. No evidence has been found for a possible monophyly of Canalipalpata or Scolecida. In all analyses a placement of the Echiura as a derived polychaete ingroup with a close relationship to the Capitellidae is confirmed. The orbiniids appear paraphyletic with regard to Questa. Travisia is transferred from Opheliidae to Scalibregmatidae. The remaining opheliids include a yet undescribed ctenodrilid species from Elba, whereas the other investigated ctenodrilid Ctenodrilus serratus groups with the Cirratulidae and shows a close affinity to the cirratulid genus Dodecaceria. A common ancestry of Branchiomaldane and Arenicola, which has been predicted on morphological data, is confirmed by the analysis and a sistergroup relationship between Arenicolidae and Maldanidae is also recovered. These results support our assumption that on the basis of a broader taxon sampling the phylogenetic position of controversially discussed taxa can be inferred by using 18S rDNA sequence data.     

Marphysa (Eunicidae,polychaete, Annelida) species of the Sanguinea group from Australia,with comments on pseudo‐cryptic species

The genus Marphysa is widely collected for bait by recreational fishermen in Australia, and yet the number of species remains unresolved. A new species is described together with additional information on a previously described species. This study reveals that while species of Marphysa superficially resemble one another, detailed studies on the distribution of different types of chaetae along the body, together with molecular studies, uncover species which may co‐occur. Correct identification is critical for management of these largely intertidal species. This study also highlights the increasing awareness of the presence of pseudo‐cryptic species in polychaetes.     

Eunicid polychaetes (Annelida) from Scandinavian and adjacent waters. Family Eunicidae

Four species of Eunice [E. pennata (0. F. Müller, 1776), E. dubitata Fauchald, 1974, E. norvegica (Linné, 1767), and E. harassii (Audouin & Milne-Edwards, 1833)] and one species of Marphysa [M . sp., close to M. sanguinea (Montagu, 1815)] are described and a branchial formula is proposed. The genus Marphysa is reported from Scandinavian waters for the first time. The specimen of Marphysa studied has tridentate composite falcigers as well as composite spinigers in the anterior setigers, whereas M. sanguinea has been reported to have composite spinigers only. The geographical distribution of all five species is given and intraspecific variation is discussed. Reports of E. oerstedii (Stimpson, 1853) from Europe are discussed and specimens of this species are compared with E. dubitata . The behaviour of E. pennata and E. dubitata has been observed in aquaria.     

Ultrastructure of the nuchal organs in the polychaete Platynereis dumerilii (Annelida,Nereididae)

Abstract. We examined the nuchal organs of adults of the nereidid polychaete Platynereis dumerilii by means of scanning and transmission electron microscopy. The most prominent features of the nuchal organs are paired ciliary bands located dorsolaterally at the posterior margin of the prostomium. They are composed of primary sensory cells and multiciliated supporting cells, both covered by a thin cuticle. The supporting cells have motile cilia that penetrate the cuticle and are responsible for the movement of water. Subapically, they have a narrowed neck region; the spaces between the neck regions of these supporting cells comprise the olfactory chamber. The dendrites of the sensory cells give rise to a single modified cilium that crosses the olfactory chamber; numerous thin microvillus-like processes, presumably extending from the sensory cells, also traverse the olfactory chamber. At the periphery of the ciliated epithelium runs a large nervous process between the ciliated supporting cells. It consists of smaller bundles of sensory dendrites that unite to form the nuchal nerve, which leaves the ciliated epithelium basally and runs toward the posterior part of the brain, where the perikarya of the sensory cells are located in clusters. The ciliated epithelium of the nuchal organs is surrounded by non-ciliated, peripheral epidermal cells. Those immediately adjacent to the ciliated supporting cells have a granular cuticle; those further away have a smooth cuticle. The nuchal organs of epitokous individuals of P. dumerilii are similar to those described previously in other species of polychaetes and are a useful model for understanding the development of nuchal organs in polychaetes.     

Anterior regeneration in the polychaete Marenzelleria viridis (Annelida: Spionidae)

The objective of this study was to examine the regeneration capacity of the spionid polychaete Marenzelleria viridis from Long Island, New York. In the field, ~7% of the worms exhibited regeneration of the anterior end. In the laboratory, worms were ablated at the 10th–50th chaetiger and their regeneration documented. Anterior morphogenesis was similar to that previously reported for spionids, with wound healing, blastema formation, differentiation of segments, and formation of feeding and sensory structures (mouth, palps, nuchal organs) occurring within 14 d. Unlike in some spionids, the segments do not appear to all form simultaneously from the blastema; rather, external differentiation of segments was observed from posterior to anterior on the regenerate. The number of segments replaced was equal to the number ablated for up to 10 segments. A maximum of 17 segments were replaced when 20–30 chaetigers were ablated, and the number replaced decreased to 14 when 40–50 chaetigers were ablated. Survival and normal growth of the worms decreased with more chaetigers ablated; a significantly higher number of worms died or grew abnormally with ≥30 chaetigers ablated, compared to worms with ≤20 chaetigers ablated. Members of M. viridis could be valuable model organisms in the study of the cellular mechanisms involved in regeneration, and further research on regeneration in the field should be completed.     

Ultrastructure of the eyespot in three polychaete trochophore larvae (Annelida)

Summary The eyespot is structurally similar in trochophore larvae of Harmothoe imbricata, Serpula vermicularis and Spirobranchus giganteus. In the receptor cell parallel lamellae lie below a tuft of microvilli which extends into a hollow in one side of the pigment cell. In 1-eyed trochophores this space connects with the outside via a small pore. In eyes preserved during the day there is evidence of a membrane breakdown in both lamellae and microvilli as well as indications of a membrane-fragment disposal system involving the receptor cell, the pigment cell and the eyespot pore. The orientation of the eyespot of S. giganteus is the reverse of that found in S. vermicularis, a situation that may be associated with ecologically significant differences in behaviour.     

Pigment chemistry, taxonomy and phylogeny of the Hypoxyloideae (Xylariaceae)

The Hypoxyloideae (Xylariaceae with Nodulisporium-like anamorphs) were evaluated by a morphological and HPLC-based chemotaxonomic survey of more than 2000 specimens and cultures. Conspecificity of recent records with ancient type specimens were established in many cases by HPLC, since their characteristic metabolites may remain stable for over 200 years. Most constitute novel natural products that were identified in the course of concurrent "mycochemical" studies. A comparison of HPLC profiles considering relationships within the Hypoxyloideae as inferred from the biogenesis of these pigments agreed fairly with concurrent molecular phylogenetic studies, based on sequences of actin, beta-tubulin, and 5.8S/ITS nrDNA genes. Anamorphic morphology and secondary metabolism of cultures agreed well at generic level and above. A combination of chemical and morphological traits is favored over PCR-based approaches for species discrimination, if only relatively few taxa of these diverse genera have been sequenced. An overview on the chemical structures and biological activities of the characteristic metabolites is provided, their ecological importance is discussed, and the utility of chemotaxonomy to support and predict phylogenetic relationships in the Hypoxyloidae is demonstrated. A polythetic approach is most useful to elucidate the phylogeny of the Xylariaceae. Chemotaxonomy to assess fungal biodiversity has considerable utility.     

Description and relationships of Chaetopterus pugaporcinus, an unusual pelagic polychaete (Annelida, Chaetopteridae)

An extraordinary new species, Chaetopterus pugaporcinus, is described from eight specimens collected from deep mesopelagic waters off Monterey Bay, California, by remotely operated vehicles. All specimens exhibit a consistent combination of both adult and larval characteristics, leaving in question the maturity of the specimens. All specimens lack ciliated larval bands and the stout, modified chaetae (cutting spines) typically found in segment A4 of chaetopterids. If the specimens described here are larvae, they are remarkable for their size, which ranged from 10 to 21 mm total length, nearly twice the length of the largest polychaete larvae previously reported and 5 to 10 times larger than known chaetopterid larvae. Then too, their lack of segment addition prior to settlement would be atypical. If adult, they are particularly unusual in their habitat choice and body form. Morphology of the uncini and comparison to larval morphology indicated a close relationship to either Chaetopterus or Mesochaetopterus. However, the lack of cutting spines and typical adult morphology made it impossible to determine to what genus this species should be allied. Thus, we carried out the first molecular phylogenetic analysis of the Chaetopteridae in order to appropriately place and name the new species. Three partial genes were sequenced for 21 annelid species. The sequencing also provides the first molecular evidence that Chaetopterus variopedatus sensu Hartman (1959) is not a single cosmopolitan species. The question of C. pugaporcinus being a delayed larva or a genuine holopelagic chaetopterid is discussed.     

18S rDNA phylogeny of Clitellata (Annelida)

The phylogeny of Clitellata was analysed using 18S rDNA sequences of a selection of species representing Hirudinida, Acanthobdellida, Branchiobdellida and 10 oligochaetous families. Eleven new 18S sequences of Capilloventridae (one), Haplotaxidae (one), Propappidae (one), Enchytraeidae (two), Lumbricidae (one), Almidae (one), Megascolecidae (two), Lumbriculidae (one), and Phreodrilidae (one) are reported and aligned together with corresponding sequences of 28 previously studied clitellate taxa. Twelve polychaete species were used as an outgroup. The analysis supports an earlier hypothesis based on morphological features that Capilloventridae represents a basal clade of Clitellata; in the 18S tree it shows a sister-group relationship to all other clitellates. The remaining clitellate taxa form a basal dichotomy, one clade containing Tubificidae (including the former 'Naididae'), Phreodrilidae, Haplotaxidae, and Propappidae, the other clade with two subgroups: (1) Lumbriculidae together with all leech-like taxa (Acanthobdellida, Branchiobdellida and Hirudinida), and (2) Enchytraeidae together with a monophyletic group of all earthworms included in the study (Lumbricidae, Almidae and Megascolecidae). These earthworms are members of the taxon Crassiclitellata, the monophyly of which is thus supported by the data. The tree also shows support for the hypothesis that the first clitellates were aquatic. The position of the single species representing Haplotaxidae is not as basal as could have been expected from earlier morphology-based conclusions about the ancestral status of this family. However, if Haplotaxidae is indeed a paraphyletic assemblage of relict taxa, a higher number of representatives will be needed to resolve its exact relationships with the other clitellates.     

Three nephromixial patterns in polychaete species currently assigned to the genus Pista (Annelida,Terebellidae)

A comparative morphological study of nephromixial systems in three Californian terebellid polchaetes currently assigned to the genus Pista shows that P. fimbriata has all attributes of the generic type, but that P. pacifica and P. elongata differ markedly. The features of typical Pista include (among others): two pairs of usually unequal branchiae, long-handled anterior uncini (hooks) of crested avicular (bird-head-like) from, muddy, unornamented tubes, one pair of anterior excretory nephromixia (ENMX), and two pairs of separate thoracic reproductive nephromixia (RNMX) with genital papillae on segments VI and VII. A review indicates that P. fimbriata shares these typical features with practically all adequately described Pista species. However, P. pacifica and P. elongata possess three pairs of branchiae, long-handled uncini of distinctive crochet-like form, and membranous tubes with apertural hoods. Both have two pairs of ENMX, the first supplied by one pair of ciliated renal funnels, the second by two pairs of such funnels. But they differ in their RNMX: P. pacifica has three pairs of complex RNMX, those on each side united by a common duct. P. elongata has 11–13 pairs of simple RNMX united by common ducts. Although these species do not fit into Pista, no genus has been found to accommodate them. Generic placement is complicated by the fact that no instances of intra-generic nephromixial variation have been reported in the Terebellidae, although inter-generic variation is well known. If they are congeneric, this would be the first example of intrageneric RNMX variation in Terebellidae. But if assigned to separate genera or subgenera on the basis of their RNMX, their similarity of anterior uncini might be attributable to parallel or convergent adaptation to life in comparable tubes. More evidence, including molecular analysis, is needed for phylogenetic studies of Terebellidae. © 1992 Wiley-Liss, Inc.     

Morphology,phylogeny and taxonomy of the genus Sectonema (Nematoda,Aporcelaimidae)

This contribution provides new insights in the phylogeny and taxonomy of the nematode genus Sectonema with an integrative approach. A brief historical outline of the matter is presented. Then, the morphological pattern of the genus is revised and illustrated, the nature of its stomatal protruding structure, either a reduced odontostyle or a mural tooth, being its most relevant diagnostic feature. The existence of cilia‐ or seta‐like structures in the perioral area and/or at the anterior part of cheilostom of some species is evidenced by SEM observations for the first time. Available molecular data (D2–D3 LSU‐rRNA gene) are analysed, including two new sequences of S. septentrionale from Spain. The monophyly of the genus is confirmed, and two species groups with geographical projection are tentatively identified. A close relationship with Metaporcelaimus is also demonstrated as both taxa constitute a highly supported clade. A likely polyphyly of the family Aporcelaimidae is once more demonstrated. Finally, an updated taxonomy of the genus is proposed, including revised diagnosis, list of species, identification key and a compendium of their main morphometrics.     

Molecular phylogeny of Nearctic species of Rhynchelmis (Annelida)

Zhou, H., Fend, S. V., Gustafson, D. L., De Wit, P. & Erséus, C. (2010). Molecular phylogeny of Nearctic species of Rhynchelmis (Annelida). —Zoologica Scripta, 39, 378–393. The Nearctic species of Rhynchelmis (Clitellata, Lumbriculidae) are known primarily from cool‐water habitats in western North America. Their taxonomy has so far been based on limited collections from isolated localities, using intuitive assessment of morphological characters. This approach has proved unsatisfactory when additional populations of closely related species were sampled and scrutinized for incorporation in the present classification. Therefore, in this study, mitochondrial (cytochrome c oxidase subunit I and 16S rDNA) and nuclear internal transcriber spacer (ITS rDNA) genes were analysed as phylogenetic markers of Nearctic Rhynchelmis species. A combined approach with all the three gene regions provided a better resolution than any of the individual genes by itself. The genes demonstrated monophyly of all major groupings proposed on the morphological basis. Within the Rhynchelmis yakimorum complex, however, the genetic data and distribution suggested that two clades initially referred to as a ‘R. yakimorum variant 1’, one from the lower Snake River drainage in Idaho and one from southern coastal Oregon, might represent two separate species. On the other hand, the sympatric distribution and low genetic distance between Rhynchelmis gustafsoni and a form tentatively identified as ‘R. cf. yakimorum’ (both collected in eastern Idaho) indicated conspecific status. This study also showed that the cytochrome c oxidase subunit I (COI) gene, which may be informative of recent and on‐going speciation and useful for species discrimination (as a DNA barcode), is less suitable as a single molecular marker for phylogenetic inference. Regardless of whether one deals with very closely related species (such as those of the yakimorum complex), with taxa with a wide and disjunct distribution (such as Rhynchelmis rostrata), or with more distantly related species, COI data should be supplemented by other genetic markers as well as morphological and biogeographical information.     

Molecular taxonomy of Osedax (Annelida: Siboglinidae) in the Southern Ocean

We report the discovery of three new species of Osedax in the deep Southern Ocean, expanding the diversity and geographical range of this genus of bone‐eating worms. Osedax rogersi sp. n. and Osedax crouchi sp. n. were found on a whale skeleton at 1444 m in the Kemp Caldera in the East Scotia Sea during the Chemosynthetic Ecosystems of the Southern Ocean (ChEsSo) project. The recently described species, Osedax antarcticus, found on whale bones implanted at a depth of 550–650 m off Smith Island in the Bransfield Strait, was also found inhabiting the whale skeleton in the Kemp Caldera. Osedax crouchi as well as another new species Osedax nordenskjoeldi sp. n. have also been found on the implanted whale bones off Smith Island. These two localities are approximately 1800 km apart demonstrating a wide distribution of species within the genus. We describe the three new species, O. rogersi, O. crouchi and O. nordenskjoeldi and report the second record of O. antarcticus. We also present a new phylogenetic analysis for Osedax, including data examining genetic connectivity between the Scotia Arc and the Bransfield Strait.