Phylogeny and Biogeography of Branchipolynoe (Polynoidae, Phyllodocida, Aciculata, Annelida), with Descriptions of Five New Species from Methane Seeps and Hydrothermal Vents

Methane diffusion affects characteristics of benthic communities in and around microbial mat-covered sediments in the northeastern Japan sea

We investigated relationships between features of benthic macrofaunal communities and geochemical parameters in and around microbial mat-covered sediments associated with a methane seepage on Sakata Knoll in the eastern Japan Sea. A depression on top of the knoll corresponds to a gas-hydrate-bearing area with seepage of methane-rich fluid, and microbial mats cover the seafloor sediments. Sediment cores were collected at three sites for this study: one within a microbial mat, a second a few meters outside of the microbial mat, and a third from a reference site outside the gas-hydrate-bearing areas. Morphological analysis showed that the site inside the microbial mat had higher macrofaunal density and biomass compared with the other sites. 18S rRNA gene analysis showed that annelids were dominant in the surface sediment inside the microbial mat with the possible occurrence of microbial anaerobic oxidation of methane (AOM), whereas in the surface sediments outside the microbial mat and at the reference site the predominant species belonged to phylum Cercozoa. Morphological analysis also showed that the surface sediment inside the microbial mat noticeably favored annelids, with dorvilleid Ophryotrocha sp. and ampharetid Neosabellides sp. identified as major constituents. Statistical analysis showed that sulfidic sediment conditions with concentrations of H2S up to 121 μM resulting from AOM likely resulted in the predominance of annelids with tolerance to sulfide. Both the 18S rRNA genes and macrofaunal characteristics showed that benthic biodiversity among the three sites was greatest outside the microbial mat. The site outside the microbial mat may represent geochemical transition conditions, including a lower rate of upward methane gas-flow compared with the site inside the microbial mat. The high biodiversity there might result from the presence of species specifically suited to the transition zone as well as species also found in photosynthesis-based communities of the background environment.

Reevaluation of the Systematic Status of Branchinotogluma (Annelida, Polynoidae), with the Establishment of Two New Species

Branchinotogluma is one of the most diverse genera among the polynoids inhabiting deep-sea chemosynthetic environments. A total of 14 species have been described from the hydrothermal vents and cold seeps worldwide. Our phylogenetic analyses based on four genes (COI, 16S, 18S, and 28S rRNA) recovered the current Branchinotogluma as paraphyletic, with seven clades scattered in two main clades. The monophyly of the main clade composed of Branchinotogluma (except Branchinotogluma segonzaci), Branchipolynoe, and Peinaleopolynoe is supported by the presence of 20–21 segments with 9–10 pairs of elytra, ventral papillae starting from segment 12 in males, and arborescent branchiae. The monophyly of another main clade composed of B. segonzaci, Bathykurila, Lepidonotopodium, Levensteiniella, and Thermopolynoe is supported by the presence of usually 22–30 segments with 11 pairs of elytra and the lack of ventral papillae in females. In addition, our study recognized two new species, Branchinotogluma nanhaiensis sp. nov. and B. robusta sp. nov., based on specimens collected from the deep-sea cold seeps in the South China Sea. Both the morphology and molecular phylogenetic analyses support the validity of the two new species and the sister relationships between B. nanhaiensis and B. japonicus and between B. robusta and B. pettiboneae as well.

Morphological convergence and adaptation in cave and pelagic scale worms (Polynoidae, Annelida)

Across Annelida, accessing the water column drives morphological and lifestyle modifications-yet in the primarily "benthic" scale worms, the ecological significance of swimming has largely been ignored. We investigated genetic, morphological and behavioural adaptations associated with swimming across Polynoidae, using mitogenomics and comparative methods. Mitochondrial genomes from cave and pelagic polynoids were highly similar, with non-significant rearrangements only present in cave Gesiella. Gene orders of the new mitogenomes were highly similar to shallow water species, suggestive of an underlying polynoid ground pattern. Being the first phylogenetic analyses to include the holopelagic Drieschia, we recovered this species nested among shallow water terminals, suggesting a shallow water ancestry. Based on these results, our phylogenetic reconstructions showed that swimming evolved independently three times in Polynoidae, involving convergent adaptations in morphology and motility patterns across the deep sea (Branchipolynoe), midwater (Drieschia) and anchialine caves (Pelagomacellicephala and Gesiella). Phylogenetic generalized least-squares (PGLS) analyses showed that holopelagic and anchialine cave species exhibit hypertrophy of the dorsal cirri, yet, these morphological modifications are achieved along different evolutionary pathways, i.e., elongation of the cirrophore versus style. Together, these findings suggest that a water column lifestyle elicits similar morphological adaptations, favouring bodies designed for drifting and sensing.

On the Diversity of Phyllodocida (Annelida: Errantia), with a Focus on Glyceridae, Goniadidae, Nephtyidae, Polynoidae, Sphaerodoridae, Syllidae, and the Holoplanktonic Families

Phyllodocida is a clade of errantiate annelids characterized by having ventral sensory palps, anterior enlarged cirri, axial muscular proboscis, compound chaetae (if present) with a single ligament, and of lacking dorsolateral folds. Members of most families date back to the Carboniferous, although the earliest fossil was dated from the Devonian. Phyllodocida holds 27 well-established and morphologically homogenous clades ranked as families, gathering more than 4600 currently accepted nominal species. Among them, Syllidae and Polynoidae are the most specious polychaete groups. Species of Phyllodocida are mainly found in the marine benthos, although a few inhabit freshwater, terrestrial and planktonic environments, and occur from intertidal to deep waters in all oceans. In this review, we (1) explore the current knowledge on species diversity trends (based on traditional species concept and molecular data), phylogeny, ecology, and geographic distribution for the whole group, (2) try to identify the main knowledge gaps, and (3) focus on selected families: Alciopidae, Goniadidae, Glyceridae, Iospilidae, Lopadorrhynchidae, Polynoidae, Pontodoridae, Nephtyidae, Sphaerodoridae, Syllidae, Tomopteridae, Typhloscolecidae, and Yndolaciidae. The highest species richness is concentrated in European, North American, and Australian continental shelves (reflecting a strong sampling bias). While most data come from shallow coastal and surface environments most world oceans are clearly under-studied. The overall trends indicate that new descriptions are constantly added through time and that less than 10% of the known species have molecular barcode information available.

Hungry scale worms: Phylogenetics of Peinaleopolynoe (Polynoidae, Annelida), with four new species

Polynoidae Kinberg, 1856 has five branchiate genera: Branchipolynoe Pettibone, 1984, Branchinotogluma Pettibone, 1985, Branchiplicatus Pettibone, 1985, Peinaleopolynoe Desbruyères & Laubier, 1988, and Thermopolynoe Miura, 1994, all native to deep-sea, chemosynthetic-based habitats. Of these, Peinaleopolynoe has two accepted species; Peinaleopolynoe sillardi Desbruyères & Laubier, 1988 (Atlantic Ocean) and Peinaleopolynoe santacatalina Pettibone, 1993 (East Pacific Ocean). The goal of this study was to assess the phylogenetic position of Peinaleopolynoe, utilizing DNA sequences from a broad sampling of deep-sea polynoids. Representatives from all five branchiate genera were included, several species of which were sampled from near the type localities; Branchinotogluma sandersi Pettibone, 1985 from the Galápagos Rift (E/V "Nautilus"); Peinaleopolynoe sillardi from organic remains in the Atlantic Ocean; Peinaleopolynoe santacatalina from a whalefall off southern California (R/V "Western Flyer") and Thermopolynoe branchiata Miura, 1994 from Lau Back-Arc Basin in the western Pacific (R/V "Melville"). Phylogenetic analyses were conducted using mitochondrial (COI, 16S rRNA, and CytB) and nuclear (18S rRNA, 28S rRNA, and H3) genes. The analyses revealed four new Peinaleopolynoe species from the Pacific Ocean that are formally described here: Peinaleopolynoe orphanae Hatch & Rouse, sp. nov., type locality Pescadero Basin in the Gulf of California, Mexico (R/V "Western Flyer"); Peinaleopolynoe elvisi Hatch & Rouse, sp. nov. and Peinaleopolynoe goffrediae Hatch & Rouse, sp. nov., both with a type locality in Monterey Canyon off California (R/V "Western Flyer") and Peinaleopolynoe mineoi Hatch & Rouse, sp. nov. from Costa Rica methane seeps (R/V "Falkor"). In addition to DNA sequence data, the monophyly of Peinaleopolynoe is supported by the presence of ventral papillae on segments 12-15. The results also demonstrated the paraphyly of Branchinotogluma and Lepidonotopodium Pettibone, 1983 and taxonomic revision of these genera is required. We apply the subfamily name Lepidonotopodinae Pettibone 1983, for the clade comprised of Branchipolynoe, Branchinotogluma, Bathykurila, Branchiplicatus, Lepidonotopodium, Levensteiniella Pettibone, 1985, Thermopolynoe, and Peinaleopolynoe.

Phylogeny, biogeography and systematics of Pacific vent, methane seep, and whale-fall Parougia (Dorvilleidae : Annelida), with eight new species

Dorvilleidae is a diverse group of annelids found in many marine environments and also commonly associated with chemosynthetic habitats. One dorvilleid genus, Parougia, currently has 11 described species, of which two are found at vents or seeps: Parougia wolfi and Parougia oregonensis. Eight new Parougia species are recognised and described in this study from collections in the Pacific Ocean, all from whale-falls, hydrothermal vents, or methane seeps at ~600-m depth or greater. The specimens were studied using morphology and phylogenetic analyses of DNA sequences from mitochondrial (cytochrome c oxidase subunit I, 16S rRNA, and cytochrome b) and nuclear (18S rRNA and histone 3) genes. Six sympatric Parougia spp. were found at Hydrate Ridge, Oregon, while three of the Parougia species occurred at different types of chemosynthetic habitats. Two new species were found over wide geographical and bathymetric ranges. Another dorvilleid genus, Ophryotrocha, has previously been highlighted as diversifying in the deep-sea environment. Our results document the hitherto unknown diversity of another dorvilleid genus, Parougia, at various chemosynthetic environments. http://zoobank.org/urn:lsid:zoobank.org:pub:EC7EBBEA-2FB5-43D6-BE53-1A468B541A5C