Family Dorvilleidae Research Articles

First record of the genus Eliberidens (Annelida: Dorvilleidae) from the Southwestern Atlantic Ocean and cladistic analysis of the genus

Knowledge on the family Dorvilleidae Chamberlin, 1919 is still limited, mainly due to the scarcity of studies and the rarity of many genera and species in samples collected from shallow waters to great depths. This work presents a two folds aim: i) report the first record of Eliberidens from the Southwestern Atlantic Ocean, with Eliberidens forceps Wolf, 1986 and Eliberidens hartmannschroederaeHilbig, 1995; ii) providing a morphological cladistic analysis to test the monophyly of Eliberidens and its relationship with related genera. These new records increase the taxonomic knowledge and distribution of dorvilleids in the Southern Hemisphere through a detailed description of Eliberidens species. The cladistic analysis supports the monophyly of the taxon Eliberidens by two synapomorphies: presence of geniculate chaeta with short distal end in the first parapodia and the absence of maxillary plates of superior row. The genus is a sister group of the clade formed by all dorvilleids included in the present analysis, excluding Gymnodorvillea.

New insights into the morphology and evolution of the ventral pharynx and jaws in Histriobdellidae (Eunicida, Annelida)

The jaw apparatus in several annelid families represents a powerful tool for systematic approaches and evolutionary investigations. Nevertheless, for several taxa, this character complex has scarcely been investigated, and complete comparative analyses of all annelid jaws are lacking. In our comprehensive study, we described the fine structure of the jaw apparatus and the ventral pharyngeal organ (VPO) in Histriobdella homari – a minute ectocommensal of lobsters putatively belonging to the Eunicida – using different comparative morphological approaches, including SEM, TEM, CLSM and subsequent 3D reconstruction. The H. homari jaw apparatus is composed of ventral paired mandibles and dorsal symmetrical maxillae consisting of numerous dental plates, ventral carriers and an unpaired dorsal rod, and the general assemblage and arrangement of the different parts are highly comparable to those of other eunicid families. The jaw ultrastructure of histriobdellids resembles that of the families Dorvilleidae and (juvenile) Onuphidae. Furthermore, our data reveal that in the process of development of the jaw apparatus, the mandibles, maxillae II and unpaired dorsal rod are formed first, and the remaining maxillae and ventral carriers appear later. Notably, the muscular apparatus differs from that in Dorvilleidae and Onuphidae in terms of the number and arrangement of muscle fibers encompassing the jaws – not only because of the very small size of Histriobdella but also because histriobdellid maxillary protraction occurs due to straightening of the dorsal rod and thus requires a different muscular scaffold. Based on our investigations, the arrangement of the muscular apparatus of the jaws, the presence of paired ventral carriers and the dorsal rod, and the morphology of the ventral pharyngeal organ represent a histriobdellid autapomorphy. Our datasets form a basis for further comparative analyses to elucidate the evolution of Eunicida and jaw-bearing Annelida.

A new species of Protodorvillea (Polychaeta: Dorvilleidae) from the Western Mediterranean Sea

A new species of Dorvilleidae, Protodorvillea artemidis sp. nov., is described from the soft bottom of the Gulf of Taranto (northern Ionian Sea) and the Straits of Messina (southern Tyrrhenian Sea), in the western Mediterranean Sea. The specimens were collected in October 2014, near the village of Rossano Calabro (Southern Italy, Ionian Sea), and in July 2016 off the village of Scilla (Southern Italy, Tyrrhenian Sea), from 6 to 38 m depth. Protodorvillea artemidis sp. nov. is characterised by four eyes, two short clavate antennae, dorsal and ventral cirri from the first parapodium, a long subacicular falciger reminiscent of that of Dorvillea, and the simultaneous occurrence of supraacicular and subacicular cultriform chaetae with serrated edges. Protodorvillea artemidis sp. nov. is similar to P. kefersteini (McIntosh, 1869) but differs from this species mainly by morphological characteristics of prostomium, mouth parts, and supraacicular and subacicualar chaetae. Morphological characters important for differentiation of the new species herein described from congeneric species are discussed. The description of P. artemidis sp. nov. helps to improve the knowledge on the diversity of Mediterranean invertebrates, and specifically on the family Dorvilleidae, which is still poorly known and includes many opportunistic species, early indicators of pollution. urn:lsid:zoobank.org:pub:AC147ADF-762A-4797-A9AE-FC0BA1219D1A

Macrobenthic community structure in the deep Gulf of Mexico one year after the Deepwater Horizon blowout

The impacts of the 2010 Deepwater Horizon (DWH) disaster on deep-sea Gulf of Mexico benthic communities were analyzed one year after the blowout. Richness, diversity, and evenness were severely impaired within a radius of approximately 1km around the DWH wellhead. However, lower diversity than background was observed in several stations up to 29km to the southwest of the wellhead. Compared to samples from 2010, abundance near the DWH wellhead increased in 2011 with some of the highest values found at stations within the 1km radius. The increase was mostly caused by the high abundance of opportunistic polychaetes of the family Dorvilleidae, genus Ophryotrocha. At contaminated stations near the DWH wellhead, diversity did not change with increased sampling area, whereas a steep increase of diversity with increasing sampling area was observed at stations farther from the wellhead. The spatial extent of DWH impacts appeared to decrease from 2010 to 2011. Impacts on diversity near the wellhead were still observed; however, the large increase in abundance may indicate the initial stages of recovery, year-to-year variability, or an early stage of succession following a disturbance; and this can be resolved only with additional temporal sampling.

Macrofaunal communities associated with chemosynthetic habitats from the U.S. Atlantic margin: A comparison among depth and habitat types

Hydrocarbon seeps support distinct benthic communities capable of tolerating extreme environmental conditions and utilizing reduced chemical compounds for nutrition. In recent years, several locations of methane seepage have been mapped along the U.S. Atlantic continental slope. In 2012 and 2013, two newly discovered seeps were investigated in this region: a shallow site near Baltimore Canyon (BCS, 366–412m) and a deep site near Norfolk Canyon (NCS, 1467–1602m), with both sites containing extensive chemosynthetic mussel bed and microbial mat habitats. Sediment push cores, suction samples, and Ekman box cores were collected to quantify the abundance, diversity, and community structure of benthic macrofauna (>300μm) in mussel beds, mats, and slope habitats at both sites. Community data from the deep site were also assessed in relation to the associated sediment environment (organic carbon and nitrogen, stable carbon and nitrogen isotopes, grain size, and depth). Infaunal assemblages and densities differed both between depths and among habitat types. Macrofaunal densities in microbial mats were four times greater than those present in mussel beds and slope sediments and were dominated by the annelid families Dorvilleidae, Capitellidae, and Tubificidae, while mussel habitats had higher proportions of crustaceans. Diversity was lower in BCS microbial mat habitats, but higher in mussel and slope sediments compared to NCS habitats. Multivariate statistical analysis revealed specific sediment properties as important for distinguishing the macrofaunal communities, including larger grain sizes present within NCS microbial mat habitats and depleted stable carbon isotopes (δ13C) in sediments present at mussel beds. These results suggest that habitat differences in the quality and source of organic matter are driving the observed patterns in the infaunal assemblages, including high β diversity and high variability in the macrofaunal community composition. This study is the first investigation of seep infauna along the U.S. Atlantic slope north of the Blake Ridge Diapir and provides a baseline for future regional comparisons to other seep habitats along the Atlantic margin.

The seasonal dynamics of six species of Dorvilleidae (Polychaeta) in the harbour of La Spezia (Italy)

AbstractIn the harbour of La Spezia (Italy) six polychaete species belonging to the family Dorvilleidae are present. The population dynamics of Dinophilus gyrociliatus, Ophryotrocha hartmanni, O. japonica, O. labronica, O. puerilis and Schistomeringos rudolphii has been studied from August 2002 to August 2003. The density of each species was considerably different and during the year there was a species succession that alternated in dominating the community. The role of the life‐history characteristics of each species and environmental conditions in determining the population dynamics are discussed.

Structure and Composition of the Polychaete Community from Bahia San Quintin, Pacific Coast of Baja California, Mexico

The diversity patterns of the polychaete fauna from a Pacific coastal lagoon were described. Polychaetes were collected in 1995 and 1998. This lagoon is formed by 2 arms: the western arm named Bahia Falsa and the eastern arm named Bahia San Quintin. 46 stations were sampled with a geological box corer. A total of 3,275 polychaetes, 28 families, 56 genera, and 104 species were identified in 1995, and 3,168 polychaetes were collected in 1998, 21 families, 39 genera and 65 species. From all the macrofauna collected in both surveys, polychaetes represented 45.2%. From the species collected, 55% correspond to new records for the area. Families Dorvilleidae, Polynoidae, Oweniidae, Scalibregmatidae, Sternapsidae and Sigalionidae present in 1995, were not in 1998 survey.The stations with higher abundances: (> 100 specimens/0.02 m2) were located on the southern half of Bahia San Quintin. Species richness and diversity were also higher in San Quintin Bay. From the 30 families previously reported for San Quintin lagoon, 23 have been collected and 6 families were added: Ampharetidae, Oweniidae, Scalibregmatidae, Sternapsidae, Dorvilleidae and Sigalionidae. Families not found in both surveys were: Paraonidae, Magelonidae, Apistobranchidae, Sphaerodoridae, Trichobranchidae, Chrysopetalidae and Arenicolidae.Results showed slightly lower redox potential values (−336 to 187 mV), slightly higher sediment temperatures (19.8°–22.1°C) and organic matter contents (0.3–4.1%) in 1998.From 1995 to 1998 a change in the composition and structure of the polychaete communities was noted; species richness diminished from 104 to 65 species. The trophic complexity changed with an increase of deposit-feeders, the abundance of other trophic categories decreased, indicating a loss of complexity. Significant changes in the abundance of some families were detected, some increased their abundances: Spionidae from 17% to 48%, Orbiniidae from 4% to 13%; other families decreased in terms of abundance and number of species: Lumbrinereidae from 11% to 1.4%, Nereididae from 9% to 1% and Sabellidae from 14% to 5%. These modifications altered the composition and structure of the polychaete communities in this lagoon. Increased anthropogenic disturbance (oyster culture, agriculture) and environmental variability due to the ENSO 97–98 may have affected recruitment and survival of some polychaete species.

Spatial heterogeneity of macrofauna at northern California methane seeps: influence of sulfide concentration and fluid flow

Relationships among fluid flow, sulfide concentration, sulfur bacteria and macrofaunal assemblages were examined at methane seeps on the northern California margin, near the mouth of the Eel River (512 to 525 m). Over a 6 mo period, sediments covered with microbial mats exhibited significant but variable outflow of altered fluids, with no flow reversals. This fluid flow was associated with high porewater sulfide concentrations (up to 20 mM) and almost no oxygen penetration of sedi- ments ( 300 µm), but biomass and diversity (no. species per core, E(S100), H ') were lower and composition varied in the sulfidic microbial mat sediments relative to clam-bed and non-seep sediments. The community in microbial mat-covered sediments consisted largely (82%) of 6 species in the polychaete family Dorvilleidae, whereas the clam-bed and non-seep microhabitats supported a mixture of annelids, peracarid crustaceans, nemerteans, and mollusks. Vertical microprofiling of sulfide in animal cores indicated that most taxa avoid H2S concentrations >1 mM. However, sulfide-oxidizing filamentous bacteria, dorvilleid polychaetes and bivalves (mainly V. pacifica) exhibited highest densities at sul- fide concentrations of 1 to 5 mM sulfide. Horizontal and vertical patterns of sulfide availability have a strong influence on the fine-scale distribution, structure and composition of macrofaunal assem- blages inhabiting methane seeps and must be accounted for when characterizing the microbiology and ecology of seep habitats.

A new genus and species of Dorvilleidae (Annelida, Polychaeta) from Bermuda, with a phylogenetic analysis of Dorvilleidae, Iphitimidae and Dinophilidae

Neotenotrocha sterreri gen. et sp. n. is described from Bermuda. It is a gonochoristic. interstitial polychaete exhibiting sexual dimorphism. The maximum length of males is only 140 μm. while females may be up to 255 μm long. They are thus the smallest polychactes known to contain a mature ovary. The new species is referred to the polychaete family Dorvilleidae, primarily due to the presence of a etenognath jaw apparatus. In almost all external characters the new form is strongly reduced. lacking parapodia, setae, antennae, and palps, whereas larval characters such as trochae and a neurotroch are retained in adults. In the light of earlier literature on phylogeny within Dorvilleidae and the likelihood that Iphitimidae and Dinophilidae are closely affiliated with the latter family, the unique combination of characters in Neotenotrocha is of special interest. A phylogenetic analysis of all apparently valid genera in the three families leads to the hypothesis that Dinophilidae and Iphitimidae represent monophyletic and paraphyletic subgroups. respectively, within Dorvilleidae. Accordingly. the definition of Dorvilleidae is emended and a key to the genera provided. The species Ougia macilenta (Oug, 1978) is referred to Parougia Wolf. 1986 and the generic status of Meiodorvillea apalpata Jumars. 1974 and Protodorvillea gaspeensis Pettibone. 1961 is discussed. Some remarks on the applicability of concepts such as neoteny and progenesis in the characterisation of interstitial dorvilleids are included. On the basis of the cladogram mid these considerations. it is hypothesized that this group may have originated in the single evolutionary event.

Dorvilleidae (Annelida:Polychaeta) from the U.S. Atlantic slope and rise. Description of two new genera and 14 new species, with a generic revision of Ophryotrocha

The present paper contains descriptions of 14 new species of dorvilleid polychaetes that are part of a highly diverse benthic infauna sampled on the U.S. Atlantic slope and rise between the Canadian border and South Carolina. Quantitative samples were taken with a Hessler‐Sandia box core during 18 cruises between 1983 and 1987. Samples were sieved through screens having a mesh opening of 300 μ. The newly described species belong to the genera Ophryorrocha. Exallopus. Parophryotrocha and two new genera, Pseudophryotrocha gen.n. and Anchidorvillea gen.n. An emended generic diagnosis of Ophryotrocha is provided to accommodate some of the new species, but also to include a group of atypical species described earlier by several authors who had modified the generic concept of Ophryotrocha without providing a formal emendation. The genus Ophryotrocha is revised to contain 31 species helonging to two species groups. A comparison of a suite of morphologic characters, however. indicates that these species addressed in this paper are discussed in the context of the entire family Dorvilleidae.

Interstitial Dorvilleidae (Annelida, Polychaeta) from Europe, Australia and New Zealand

Four dorvilleid species new to science are described from intertidal and subtidal sandy sediments. For three of them new genera are erected: Coralliotrocha natans gen. et sp.n., Microdorvillea otagensis gen. et sp.n. and Pusillotrocha Åkessoni gen. et sp.n. One species represents the first record of the genus Pettiboneia from Australia, P. australiensis sp.n. Ophryotrocha minuta Levi, 1954 redescribed from Helgoland is transferred to a different genus, Arenotrocha gen.n. The present taxa belong to a morphological series of species with an increasing degree of neoteny in the family Dorvilleidae.

Scolécodontes, assemblage et appareil de vers annelidespolychetes errantes de l'aptien de la région d'Agadir, Maroc

From the Aptian scolecodonts inventory of the Agadir area one jaw apparatus and one joining of polychetes are reconstructed. One is the elementary species Schistomeringos expectatus Szaniawski & Gazdzicki, 1978 , the oldest representative of the multielementary family Dorvilleidae Chamberlin 1919. The other is a representative of either the multielementary families Atraktoprionidae Kielan Jaworowska 1966 emend. Kozur, 1970 or Arabellidae Hartman 1944. This joining is considered as an hypothesis since all the necessary criteria, defined by H. Szaniawski & A. Gazdzicki 1978, are not all present.

Lower Jurassic scolecodonts from the vicentinian Alps (northeastern Italy), representing the family Dorvilleidae Chamberlin, 1919

The presence of relatively rich and well-preserved scolecodont assemblages in the Rotzo Member of the Noriglio Grey Limestone Formation of the Vicentinian Alps (Late Pliensbachian to Early Toarcian in age) enabled the description oof the jaw apparatus of a polychaete of the family Dorvilleidae Chamberlin, 1919, viz. Schistomeringos expectatus Szaniawski et Gaździcki, 1978. The material described so far constitutes the oldest record of this family.