Ophryotrocha Species Research Articles

Life history traits for Ophryotrocha craigsmithi (Wiklund, Glover & Dahlgren, 2009), a candidate species in integrated multitrophic aquaculture

Ophryotrocha craigsmithi (Wiklund, Glover & Dahlgren, 2009) has repeatedly been observed in high densities at salmonid fish farms in Norway and has been shown to feed on the organic waste released during fish production. This species has therefore been pointed out as a candidate for the benthic component of integrated multitrophic aquaculture (IMTA). Little is known about the life history traits of Ophryotrocha species found at greater depths in temperate waters. Insight into life traits is of key importance in evaluating the bio-mitigation and harvest potential of (benthic) species within IMTA systems. In this study, we aimed to describe key life history traits for O. craigsmithi, such as growth, reproductive pattern, and offset of reproduction. The main findings are as follows: (I) O. craigsmithi exhibits early sexual maturation and rapid growth, going from 5 to 16 mm in length in 8 weeks; (II) their estimated lifetime is approximately 15 weeks with a generation time of 4 weeks; (III) there are strong indications that they are gonochoric semicontinuous spawners; (IV) the majority of mature eggs ranged from 120 to 150 µm; and (V) the larvae developed into a free-swimming stage after approximately 1 week. To this end, we present a framework for assessing the suitability of deposit-feeding polychaetes as candidate species in IMTA, considering environmental adaptiveness, production potential, as well as carbon and nitrogen mitigation capacity. On the basis of this, O. craigsmithi shows a high suitability as an extractive farmed species in benthic IMTA.

New species of Ophryotrocha (Annelida: Dorvilleidae) associated with deep-sea reducing habitats in the Bering Sea, Northwest Pacific

Four species of Ophryotrocha (Annelida, Dorvilleidae) from deep-sea reducing habitats (methane seeps on the Koryak slope and hydrothermal vents of the submarine Piip Volcano) were collected in the western part of the Bering Sea, NW Pacific. Descriptions of two of these new Ophryotrocha species, namely O. beringiana sp. nov. and O. seepens sp. nov., confirmed with molecular analyses, are presented herein. The detailed descriptions with electron microscopy illustrations for the new species are presented and their differences from similar species are discussed. In addition to the morphological description, the phylogenetic relationships of the new dorvilleids are provided using two nuclear (18S RNA, histone H3) and two mitochondrial (16S RNA and cytochrome c oxidase subunit 1, COI) markers in an analysis containing 54 terminal taxa. Phylogenetic analyses using MrBayes and Maximum Likelihood analyses show that O. beringiana sp. nov. and O. seepens sp. nov. are sister species, and together with O. platykephale, O. globopalpata and O. flabella form a subclade of deep-sea Pacific species within a clade referred to here as ‘globopalpata–platykephale’. In our molecular analysis, the clade currently consists of ten species, nine of those (except for O. longidentata, the only shallow Atlantic species not reported in chemosynthetic habitats) have been described from Pacific deep-sea reducing environments (hydrothermal vents, cold methane seeps, whale-falls). The ecology and geographic distribution of the reported species are discussed.

Four new species and further records of Dorvilleidae (Annelida, Polychaeta) from deep-sea organic substrata, NE Atlantic

Eight species of Ophryotrocha and one of Parougia were identified from organic substrata (wood and alfalfa) sampled at the Gulf of Cadiz and Western Iberian Margin (NE Atlantic). Morphological examination and molecular phylogenetic analyses, based on the nuclear gene H3 and the mitochondrial gene 16S, indicate the presence of four species new to science: Ophryotrocha chemecoli sp. nov., O. nunezi sp. nov., O. geoffreadi sp. nov. and Parougia ougi sp. nov. The geographic and/or bathymetric distribution is extended for four previously known species: O. cantabrica, O. hartmanni, O. mammillata and O. scutellus. Another species may also have its distribution extended, pending the molecular confirmation of its identity: O. lipscombae. Full descriptions and figures are given for all the new species and, when justified, also for the previously known ones. The original description of O. scutellus is amended. New DNA sequences are given for eight of the nine species studied here. The ecology and geographic distribution of the reported species is discussed.

Life-history traits display strong associations to genome size in annelids

Genome size, known also as the C-value, has been proposed as an important determinant of life-history variation in numerous animal taxa. We assessed the relationships between genome size and fitness-related life-history traits in six species of interstitial marine annelids of the genus Ophryotrocha. Life-history traits and genome size data obtained from 18 additional annelid species were included in our analyses to have a broader phylogenetic scope. Unexpectedly, genome sizes assessed here by flow cytometry in four Ophryotrocha species were three times larger than previously reported values obtained using Feulgen densitometry. This has implications for the hypothesis that harsh interstitial habitats select for small genomes in meiofaunal annelids. Within the genus Ophryotrocha, significant and positive relationships were found between genome size and nucleus size, and between genome size, age at first egg mass deposition, body size and lifespan. These relationships held up in the broader phylogenetic comparison. Our study provides evidence for the important role played by genome size in the evolution of life-history traits in annelids.

Extensive gene rearrangements in the mitogenomes of congeneric annelid species and insights on the evolutionary history of the genus Ophryotrocha

BackgroundAnnelids are one the most speciose and ecologically diverse groups of metazoans. Although a significant effort has been recently invested in sequencing genomes of a wide array of metazoans, many orders and families within the phylum Annelida are still represented by a single specimen of a single species. The genus of interstitial annelids Ophryotrocha (Dorvilleidae, Errantia, Annelida) is among these neglected groups, despite its extensive use as model organism in numerous studies on the evolution of life history, physiological and ecological traits. To compensate for the paucity of genomic information in this genus, we here obtained novel complete mitochondrial genomes of six Ophryotrocha species using next generation sequencing. In addition, we investigated the evolution of the reproductive mode in the Ophryotrocha genus using a phylogeny based on two mitochondrial markers (COXI and 16S rDNA) and one nuclear fragment (Histone H3).ResultsSurprisingly, gene order was not conserved among the six Ophryotrocha species investigated, and varied greatly as compared to those found in other annelid species within the class Errantia. The mitogenome phylogeny for the six Ophryotrocha species displayed a separation of gonochoric and hermaphroditic species. However, this separation was not observed in the phylogeny based on the COX1, 16S rDNA, and H3 genes. Parsimony and Bayesian ancestral trait reconstruction indicated that gonochorism was the most parsimonious ancestral reproductive mode in Ophryotrocha spp.ConclusionsOur results highlight the remarkably high level of gene order variation among congeneric species, even in annelids. This encourages the need for additional mitogenome sequencing of annelid taxa in order to properly understand its mtDNA evolution, high biodiversity and phylogenetic relationships.

A new species of Ophryotrocha (Annelida, Eunicida, Dorvilleidae) from hydrothermal vents on the Southwest Indian Ridge.

Dorvilleids were collected from hydrothermal vents on the Southwest Indian Ridge by manned submersible Jiaolong. These represent a new species of Ophryotrocha that is here described as Ophryotrocha jiaolongi sp. n. This is the first dorvilleid described from vents on the Southwest Indian Ridge. It most closely resembles another vent species, Ophryotrocha akessoni Blake, 1985 from the Galapagos Rift, but can be distinguished by its antennae, palps, jaw structure. The new species has particularly distinctive mandibles, which allow it to be easily identified.

Is the Antarctic Ophryotrocha orensanzi (Annelida: Dorvilleidae) a circumpolar non-specialized opportunist?

The dorvilleid polychaete Ophryotrocha orensanzi is reported from the vicinity of Casey station, East Antarctica, an astounding range extension from its previous records in the South Shetland Islands to the opposite side of the Antarctic continent, suggesting that it is a circumpolar species. Genetic studies confirmed the conspecificity and the inferred haplotype network suggests that the two populations studied are genetically connected. Morphological studies of the newly collected material revealed that the jaw apparatus consists of the P- and K-type, in accordance with other members of the ‘lobifera’ clade. We are reporting a previously undocumented button-like structure that we are referring to as ‘nuchal papilla’ for its association with the nuchal region, and present an emended diagnosis for the species. The Casey station population was collected in a clean, unpolluted intertidal environment associated with stones and seaweeds. We are challenging the generally held opinion that Ophryotrocha species are specialists of organically enriched substrates, suggesting that, at least for the particulars of O. orensanzi, they might also be unspecialized opportunists, able to exist in the most pristine environments and having the ability to rapidly increase their population sizes under favourable conditions.

First account on the diversity of Ophryotrocha (Annelida, Dorvilleidae) from a mammal-fall in the deep-Atlantic Ocean with the description of three new species

Annelids of the genus Ophryotrocha are globally distributed in a wide variety of organically enriched habitats. Although mostly known from shallow water, the expansion of deep-sea research revealed several new Ophryotrocha species mainly associated with organic-falls, in particular with cetacean carcasses, or whale-falls. Despite the great deal of interest that fauna associated with whale-falls have attracted, very little is known about this fauna in the deep-Atlantic Ocean. Hereby we analyse, for the first time, the Ophryotrocha assemblage associated with a mammal-fall in this region of the world's ocean. Specimens were collected from the bones of degrading cow carcasses deployed in the Setúbal canyon at approximately 1000 m depth. Using morphological characters and phylogenetic analyses based on the nuclear gene H3 performed on 31 Ophryotrocha species, we report the presence of five different species, we describe three new species and extend the distribution of O. scutella. Ophryotrocha scutella was previously known from a shallow-water whale-fall and organically enriched sediments beneath a fish farm off Scandinavia and is the first species to be reported from organic-falls in both shallow and deep waters. The presence of five congeners emphasize the importance of the genus Ophryotrocha in the degradation of organic matter in the deep-sea. Our results substantially increase the number of deep Atlantic species in the genus Ophryotrocha and highlight the remarkable unknown diversity and biogeographic patterns hidden behind unstudied deep-sea habitats.http://zoobank.org/urn:lsid:zoobank.org:pub:A12699DA-E580-4782-941A-48D7B31E4DAE

A new annelid species from whalebones in Greenland and aquaculture sites in Newfoundland: Ophryotrocha cyclops, sp. nov. (Eunicida: Dorvilleidae)

A new species of Ophryotrocha was discovered on whalebones in Greenland (120 m depth) and at finfish aquaculture sites in Newfoundland (30-70 m depth), where it is considered to be a bioindicator of aquaculture-related organic enrichment. Phylogenetic analyses based on three genes (COI, 16S mitochondrial and H3 nuclear genes) show close affinities with O. lobifera and O. craigsmithi, two species also found on both whalebones and at aquaculture sites (North Sea), and with O. shieldsi from aquaculture sites in Tasmania. The new species is named Ophryotrocha cyclops sp. nov. due to the juxtaposed, quasi-fused central eyes that give the impression of a single eye in live specimens.

Two new Antarctic Ophryotrocha (Annelida: Dorvilleidae) described from shallow-water whale bones

Marine invertebrate fauna associated with whale remains has lately attracted a great deal of interest. However, very little is known about this fauna in the Southern Ocean, an area with high abundances of cetaceans. To investigate the Antarctic organisms associated with these substrates, we conducted a study using whale bones in the shallow-waters of Deception Island (South Shetland Islands). In this paper, we describe two new species of Ophryotrocha (O. orensanzi sp. nov. and O. clava sp. nov.) from a minke whale (Balaenoptera acutorostrata) fresh caudal vertebra experimentally deployed for about a year and from an unknown whale vertebra presumably dating back to the early twentieth century whaling operations. Ophryotrocha clava sp. nov., found in relative high abundance in the fresh bone, is hypothesized to be an opportunistic species in the context of Antarctic shallow-water organically enriched environments. Ophryotrocha orensanzi sp. nov. appears to be the same species as the unnamed Palpiphitime sp., near lobifera, formerly reported from a nearby area. Phylogenetic analyses based on the nuclear gene H3 and the mitochondrial genes COI and 16S, using MrBayes and Maximum Likelihood analyses, show that O. clava sp. nov. is close to Iphitime hartmanae and is included in the ‘hartmanni’ clade, while O. orensanzi sp. nov. falls in the ‘lobifera’ clade. Remarks about their feeding preferences and ecology are also given. Our findings seem to suggest that members of the genus Ophryotrocha are important components of organically enriched Southern Ocean environments, as has been reported for this clade in other geographic areas.

Systematics and biodiversity of Ophryotrocha (Annelida, Dorvilleidae) with descriptions of six new species from deep-sea whale-fall and wood-fall habitats in the north-east Pacific

Six new Ophryotrocha species are described from five whale-falls and two wood-falls off the southern Californian coast. Phylogenetic analyses based on the nuclear gene H3 and the mitochondrial genes COI and 16S using MrBayes and maximum likelihood analyses were performed on 40 dorvilleid taxa and one outgroup. Ophryotrocha batillus sp. nov. is morphologically identical to Ophryotrocha scutellus described from a shallow water whale-fall in the North Atlantic, although the two cryptic species differ genetically. Ophryotrocha langstrumpae sp. nov. is closely related in the molecular phylogenetic analyses to these two sibling species. Ophryotrocha flabella sp. nov. is similar to Ophryotrocha globopalpata, and although there are a few morphological differences, the genetic divergence is low between the two species. Ophryotrocha nauarchus sp. nov. is sexually dimorphic, with males having appendages on the first chaetiger. Ophryotrocha magnadentata sp. nov. and Ophryotrocha longicollaris sp. nov. are sister species in our molecular analyses, and together with O. nauarchus sp. nov. and O. flabella sp. nov. they fall within a clade that includes O. globopalpata and Exallopus jumarsi described from hydrothermal vents in the Pacific Ocean and Ophryotrocha longidentata from the shallow North Atlantic. Our results highlight the remarkable unknown diversity of deep-water habitats and the role of chemosynthetic ecosystems in the evolution of deep-sea life.

The Ophryotrocha diadema group (Annelida: Dorvilleidae), with the description of two new species

This paper reviews a group of hermaphroditic Ophryotrocha species, here designated as the O. diadema group. This informal group is characterised by its unique P-maxillae and paired mammillate rosette glands. The three members of the group are simultaneous hermaphrodites and have the chromosome complement of 2n = 8. As herein defined, the group includes O. diadema, O. alborana sp. nov., and O. birgittae sp. nov.. The three species can be distinguished by the appearance of their eyes and other morphological and reproductive differences. The species are described, and their life table data is presented.

A new species of Ophryotrocha (Annelida: Dorvilleidae) associated with fish farming at Macquarie Harbour, Tasmania, Australia

A new species of Ophryotrocha (Annelida: Dorvilleidae) associated with fish farming at Macquarie Harbour, Tasmania, Australia

The Ophryotrocha labronica group (Annelida: Dorvilleidae)— with the description of seven new species

This paper reviews the group of gonochoristic Ophryotrocha species, known as the “O. labronica group”. This informal group is chararacterised by its unique maxillary P- and K-forceps and dorsomedian rosette glands. All members of the group are primarily gonochoristic and almost all have the diploid complement of chromosomes of 2n = 6. External morphological differences within the group are very slight. In males and females of all species the P-type maxillae change at maturity to the K-type with the right forceps being bifid. A jaw fossil from the Upper Cretaceous, attributable to the O. labronica group, attests to the long history of the group. As herein defined, the group includes: O. labronica labronica, O. labronica pacifica, O. costlowi sp. nov., O. dimorphica, O. japonica sp. nov., O. macrovifera sp. nov., O. notoglandulata, O. permanae sp. nov., O. robusta sp. nov., O. rubra sp. nov., O. schubravyi, O. vellae sp. nov., O. olympica, nom. nud., O. prolifica, nom. nud., and O. sativa, nom. nud.. Seven species are formally described and diagnoses are provided for all remaining taxa in the taxonomic section. This is followed by an illustrated discussion of the morphology, reproductive traits, and relationships of the members of the informal group.

A new species of Ophryotrocha (Annelida: Dorvilleidae) associated with fish farming at Macquarie Harbour, Tasmania, Australia

Ophryotrocha shieldsi, sp. nov. is described from Macquarie Harbour, Tasmania, Australia, where it occurs in high densities beneath the sea cages of fish farms. SCUBA and ROV underwater observations revealed closely spaced mounds of aggregations of the new species. It is closely related to O. lobifera Oug, a species reported from fish farms and whale-falls in the North Sea, from which it can be distinguished by its ovate rather than triangular dorsal lateral lobes, palps with small globular rather than longer digitate palpostyles, and additional jaw differences.

Jaw morphology and ontogeny in five species of Ophryotrocha

Detailed scanning electron microscopy of jaws within the genus Ophryotrocha (Dorvilleidae, Annelida) was performed on 871 jaw parts. The investigations resulted in new understandings of the ontogeny and jaw morphology and have systematic implications for the family. Five species in the genus (Ophryotrocha alborana, O. diadema, O. gracilis, O. hartmanni, and O. labronica pacifica) were kept in culture, and the development of the jaws was studied by sampling throughout their life history. Ophryotrocha species have mandibular plates that remain the same throughout ontogeny, whereas the posterior shafts elongate. Both mandibular plate morphology and shaft ontogeny have species-specific distinctions. In Ophryotrocha, the maxillae can be assigned to three to four distinct types, which are replaced by moulting. The maxillary morphology and developmental stages at which moults occur are species specific, although with broad intervals. A redefinition is given for some of the basic jaw elements, and new homologies are proposed for structures that are also present across other dorvilleid taxa.

Three new species of Ophryotrocha (Annelida: Dorvilleidae) from a whale-fall in the North-East Atlantic

Three new Ophryotrocha species are described from sites with high levels of organic carbon flux including a whale-fall at 125 m depth off the Swedish coast and sediment sampled at 104 m depth beneath a fish farm in a Norwegian fjord. Phylogenetic analyses based on the nuclear gene H3 and the mitochondrial genes COI and 16S using MrBayes and Maximum Likelihood analyses show that Ophryotrocha eutrophila sp. nov. is a close relative to Ophryotrocha puerilis, while Ophryotrocha craigsmithi sp. nov. falls together with Palpiphitime lobifera, and Ophryotrocha scutellus sp. nov. occur within the 'hartmanni' clade. The genus Ophryotrocha is in our study monophyletic only if the genera Iphitime and Palpiphitime are included. Two representatives of Ophryotrocha previously described from anthropogenically-enriched sediments are here reported for the first time in very high abundance from a naturally occurring habitat. We suggest that whale falls are important habitats for the evolution of ecosystem services such as the degradation of complex organic compounds.

Redescription of Ophryotrocha puerilis and O. labronica (Annelida, Dorvilleidae)

For more than a century, it has been pointed out that most features of the original description of Ophryotrocha puerilis Claparède & Mecznikow, 1869, probably based on a mixed population of two sympatric species, agree better with the subsequently described O. labronica La Greca & Bacci, 1962. Although O. labronica was described as a protandrous hermaphrodite that could self-fertilize, the widely distributed species is mainly gonochoristic. We will designate neotypes, redescribe these two polychaetes and review their reproduction and development to remove any confusion and uncertainty surrounding the identity of these two well-known polychaetes. We will also discuss the growth and replacement of the maxillary apparatus and the morphology and distribution of the rosette glands, providing support for the molecular phylogeny of selected Ophryotrocha species.

Biogeography and incipient speciation in Ophryotrocha labronica (Polychaeta, Dorvilleidae)

Crossing experiments were conducted between the Naples I (NI) strain of Ophryotrocha labronica labronica, three strains of O. l. pacifica from Japan (M3), Hawaii (WH) and Los Angeles (LA), two strains of O. labronica from Australia and one from an unknown origin, discovered in a Moscow aquarium, to determine the relationships between the European and Pacific subspecies, and the newly discovered strains. Previously published data combined with new results revealed several stages in the process of speciation within the sibling group. Interpopulation crosses yielded an increased sex ratio that appears to be positively related to genetic distance and to the sex ratio of the parent strains. Fecundity data demonstrated that the three northern Pacific strains are more closely related to each other than to any other strain, confirming that they are a valid subspecies, and indicate that they are the result of natural distribution. The strain of unknown origin as well as the Australian strains clearly belong to O. l. labronica. Its isolated presence in the South Pacific may be a remnant of an earlier wider distribution or an introduction of the Mediterranean population, as the life histories of Ophryotrocha species have made them prime candidates for anthropogenic dispersals.

The phylogeny ofOphryotrocha(Dorvilleidae: Eunicida: Polychaeta)

The phylogeny of 20 cultured species of Ophryotrocha, including a group of sibling species that can only be identified by biochemical or reproductive information, is estimated from a combined parsimony analysis of 32 morphological, reproductive and electrophoretic characters, with selected members of Dorvillea, Ougia and Protodorvillea used as outgroups. Sexual production in the group include simultaneous hermaphroditism, protandrous sex reversal, an exceptional male/hermaphrodite system, and gonochorism. According to the presented phylogeny, simultaneous hermaphroditism appears as the primitive state in the group. It is suggested that sequential hermaphroditism and gonochorism are independently acquired, the latter state also giving rise to the male/hermaphrodite system.