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Zootaxa Nov 2020The polynoid genus Chaetacanthus Seidler, 1922 currently includes three nominal species provided with parapodial branchiae. Members of this taxon have palps with...
The polynoid genus Chaetacanthus Seidler, 1922 currently includes three nominal species provided with parapodial branchiae. Members of this taxon have palps with longitudinal rows of papillae, notochaetae abundant and neurochaetae spinulose. Most Chaetacanthus species were originally described as belonging to Lepidonotus Leach, 1816, and some of them were later regarded as subjective synonyms of Iphione magnifica Grube, 1876, the type species for Chaetacanthus. This species was described from the Caribbean Sea and later recorded for the tropical Eastern Pacific. After the supposed Amphi-American distribution, a revision of all available material was performed in order to clarify the generic delineation, and to improve the understanding of species systematics. Further, some non-type specimens collected in Panama allowed us to have a better understanding of the variation of elytral shape and ornamentation along the body. The type material of Polynoe brasiliensis de Quatrefages, 1866 was examined and despite its poor condition, it shows parapodial branchial filaments which were overlooked in the original description; these branchiae are also present in the holotype of I. magnifica. We identify that there are no relevant difference between both species, and they are regarded as synonyms, and Chaetacanthus brasiliensis (de Quatrefages, 1866) is newly combined and is the senior synonym. On the other hand, Chaetacanthus pilosus (Treadwell, 1937), from the Eastern Pacific, and C. pomareae (Kinberg, 1856) from the South Central Pacific are redescribed, and C. harrisae n. sp., and C. ornatus n. sp. are both newly described from the Eastern Pacific. A key to identify all species of Chaetacanthus of the World, together with an appendix for the reversal of precedence of Lepidonotus Leach, 1816 over Eumolpe Oken, 1807 are also included.
Topics: Animals; Annelida; Polychaeta
PubMed: 33311270
DOI: 10.11646/zootaxa.4885.3.5 -
PloS One 2024Nereidid polychaetes are well known from shallow marine habitats, but their diversity in the deep sea is poorly known. Here we describe an unusual new nereidid species... (Review)
Review
Nereidid polychaetes are well known from shallow marine habitats, but their diversity in the deep sea is poorly known. Here we describe an unusual new nereidid species found at methane seeps off the Pacific coast of Costa Rica. Specimens of Pectinereis strickrotti gen. nov., sp. nov. had been observed dating back to 2009 swimming just above the seafloor at ~1,000 m depth but were not successfully captured until 2018. Male epitokes were collected as well as a fragment of an infaunal female found in a pushcore sample. The specimens were all confirmed as the same species based on mitochondrial COI. Phylogenetic analyses, including one based on available whole mitochondrial genomes for nereidids, revealed no close relative, allowing for the placement of the new species in its own genus within the subfamily Nereidinae. This was supported by the unusual non-reproductive and epitokous morphology, including parapodial cirrostyles as pectinate gills, hooked aciculae, elfin-shoe-shaped ventral cirrophores, and elongate, fusiform dorsal ligules emerging sub-medially to enlarged cirrophores. Additionally, the gill-bearing subfamily Dendronereidinae, generally regarded as a junior synonym of Gymnonereidinae, is reviewed and it is here reinstated and as a monogeneric taxon.
Topics: Female; Male; Animals; Gills; Phylogeny; Annelida; Polychaeta; Apocynaceae
PubMed: 38446781
DOI: 10.1371/journal.pone.0297961 -
Zootaxa Feb 2020Leocrates Kinberg, 1866 and Leocratides Ehlers, 1908 are two genera of hesionid errant annelids (Hesionidae, Hesioninae) whose species have 16 chaetigers (21 segments)....
Leocrates Kinberg, 1866 and Leocratides Ehlers, 1908 are two genera of hesionid errant annelids (Hesionidae, Hesioninae) whose species have 16 chaetigers (21 segments). Leocrates species are free living in rocky or mixed bottoms, whereas Leocratides species are usually symbiotic with hexactinellid sponges. Marian Pettibone revised both genera as part of the R/V Siboga Expedition monographs 50 years ago, and most of her ideas have remained unchallenged regarding synonymy for genera and species. For example, she included three genera as junior synonyms of Leocrates: Lamprophaes Grube, 1867, Tyrrhena Claparède, 1868, and Dalhousia McIntosh, 1885, and from 21 nominal species, she regarded only eight as valid. In this revision, all material available was studied, and different morphological patterns were noted in nuchal organs lobes, pharynx armature, and chaetal features. Leocratides species belong to a single pattern; however, in Leocrates several patterns were detected. Three patterns are present for nuchal organs lobes: barely projected posteriorly (horizontal C-shaped), markedly projected posteriorly (U-shaped), and with lateral transverse projections (L-shaped). In the pharynx, upper jaws were noted as single, fang-shaped, or as double, T-shaped structures, whereas the lower jaw can be single, fang-shaped, or a transverse plate. Neurochaetal blades can be bidentate with guards approaching subdistal tooth, unidentate without guards, or with guards hypertrophied projected beyond distal tooth. The combinations of these features are regarded as different genera and consequently, Leocrates is restricted (including Tyrrhena), but Dalhousia, and Lamprophaea (name corrected) are reinstated, and three new genus-group names are proposed: Paradalhousia n. gen., Paralamprophaea n. gen., and Paraleocrates n. gen. Further, the standardization of morphological features allowed several modifications and the recognition of novelties. Thus, four type species were redescribed, four others were reinstated, 10 were newly combined, and 18 from different World localities are described as new. The new species are Lamprophaea cornuta n. sp. from the French Polynesia, L. ockeri n. sp. from the Hawaiian Islands, L. paulayi n. sp. from the Red Sea, L. pettiboneae n. sp. from the Marshall Islands, L. pleijeli n. sp. from La Réunion, L. poupini n. sp. from the French Polynesia, Leocrates ahlfeldae n. sp. from India, L. harrisae n. sp. from the Revillagigedo Islands, L. mooreae n. sp. from New Caledonia, L. reishi n. sp. from the Marshall Islands, L. rizzoae n. sp. from the Seychelles Islands, L. rousei n. sp. from Papua New Guinea, L. seidae n. sp. from the French Polynesia, Leocratides jimii n. sp. from Madagascar, Paralamprophaea bemisae n. sp. from the Maldives, P. crosnieri n. sp. from Madagascar, P. leslieae n. sp. from Kiribati, and P. meyeri n. sp. from the French Polynesia. However, Leocrates japonicus Gustafson, 1930 is a nomen nudum. Keys are included for identifying all hesioninae genera, and for all species in all the included genera.
Topics: Animals; Annelida; Female
PubMed: 32230228
DOI: 10.11646/zootaxa.4739.1.1 -
Genes Jan 2024Frenulates are a group of sedentary Annelida within the family Siboglinidae that inhabit the ocean floor and present a unique challenge for comprehensive molecular and...
Frenulates are a group of sedentary Annelida within the family Siboglinidae that inhabit the ocean floor and present a unique challenge for comprehensive molecular and phylogenetic investigations. In this study, we focused on the frenulates, specifically assembling the mitochondrial genomes of and . The phylogenetic reconstruction placed as a sister taxon to , and as a sister taxon to , supporting the non-monophyletic nature of the genus . Overall, this study supports the phylogeny of the family Siboglinidae while highlighting the need for additional molecular data within frenulates.
Topics: Animals; Humans; Phylogeny; Genome, Mitochondrial; Polychaeta; Annelida; Siblings
PubMed: 38254966
DOI: 10.3390/genes15010077 -
Proceedings of the National Academy of... Jul 2021Our understanding of metabolic interactions between small symbiotic animals and bacteria or parasitic eukaryotes that reside within their bodies is extremely limited....
Our understanding of metabolic interactions between small symbiotic animals and bacteria or parasitic eukaryotes that reside within their bodies is extremely limited. This gap in knowledge originates from a methodological challenge, namely to connect histological changes in host tissues induced by beneficial and parasitic (micro)organisms to the underlying metabolites. We addressed this challenge and developed chemo-histo-tomography (CHEMHIST), a culture-independent approach to connect anatomic structure and metabolic function in millimeter-sized symbiotic animals. CHEMHIST combines chemical imaging of metabolites based on mass spectrometry imaging (MSI) and microanatomy-based micro-computed X-ray tomography (micro-CT) on the same animal. Both high-resolution MSI and micro-CT allowed us to correlate the distribution of metabolites to the same animal's three-dimensional (3D) histology down to submicrometer resolutions. Our protocol is compatible with tissue-specific DNA sequencing and fluorescence in situ hybridization for the taxonomic identification and localization of the associated micro(organisms). Building CHEMHIST upon in situ imaging, we sampled an earthworm from its natural habitat and created an interactive 3D model of its physical and chemical interactions with bacteria and parasitic nematodes in its tissues. Combining MSI and micro-CT, we present a methodological groundwork for connecting metabolic and anatomic phenotypes of small symbiotic animals that often represent keystone species for ecosystem functioning.
Topics: Animals; Bacteria; Histological Techniques; Host-Parasite Interactions; Imaging, Three-Dimensional; Mass Spectrometry; Oligochaeta; Symbiosis; X-Ray Microtomography
PubMed: 34183413
DOI: 10.1073/pnas.2023773118 -
Zoology (Jena, Germany) Feb 2021Amphinomid fireworms are notorious for their stinging dorsal bristles (notochaetae), but it is still unclear whether the irritation they cause is merely mechanical or if...
Amphinomid fireworms are notorious for their stinging dorsal bristles (notochaetae), but it is still unclear whether the irritation they cause is merely mechanical or if the notochaetae contain toxins. Furthermore, although fireworm chaetae have always been described as calcareous, their composition has never been investigated to date and strong debates are ongoing on their internal structure. Unravelling the native ultrastructure and composition of fireworm chaetae is the first crucial step to assess whether the hypothesis of toxin vehiculation could be fully considered. We examined for the first time the chemical and mineralogical composition, the ultrastructure and the external structure of the dorsal and ventral chaetae of the large species Hermodice carunculata. All the measurements were carried out on samples prepared without the use of chemical reagents, except for those targeted to investigate if decalcification altered the ultrastructure of the chaetae. A crystal-chemical strategy, combining chemical, diffraction and thermal analyses clearly showed the occurrence of crystalline calcium carbonate and clusters of phosphatic amorphous material. Scanning electron micrographs and energy dispersive X-ray measurements showed that the dorsal chaetae have an extremely shallow insertion point in the body respect to the ventral chaetae, that could facilitate the release of the notochaetae in the environment. Their proximal part is characterized by canals with a hexagonal pattern rich in Ca and P, followed by a large cavity upwards. The harpoon-shaped ends and the central canals of the notochaetae completely disappeared after exposure to EDTA. The notochaetae are hollow and may be able to vehicle toxins. The absence of the honeycomb pattern in the distal part of the notochaetae and their slenderness probably contribute to their brittleness and high sensitivity to breakage on contact. These observations constitute keystone understandings to shed light on fireworm defensive and offensive capacities and their ecological success.
Topics: Animal Structures; Animals; Annelida; Microscopy, Electron, Scanning
PubMed: 33227649
DOI: 10.1016/j.zool.2020.125851 -
PloS One 2022This is the first taxonomic study of cirratulid polychaetes of the genus Kirkegaardia Blake, 2016 from Brazil. Nine new species of the genus are described from the...
This is the first taxonomic study of cirratulid polychaetes of the genus Kirkegaardia Blake, 2016 from Brazil. Nine new species of the genus are described from the Southern Brazilian coast (50-3000 m deep). The genus Kirkegaardia is generally subdivided into three distinct groups of species (Kirkegaardia dorsobranchialis-heterochaeta, Kirkegaardia baptisteae-tesselata and Kirkegaardia luticastella) and several out-group species for which relationships remains to be defined. In this study, new species were included in the Kirkegaardia dorsobranchialis-heterochaeta and Kirkegaardia baptisteae-tesselata groups. Kirkegaardia dorsobranchialis-heterochaeta is characterized by thoracic parapodia elevated producing a channel between the notopodia, elongate pre-setigerous region that is either entirely smooth or modified with a dorsal ridge and/or rings, and noto- and neurosetae capillaries denticulated. As belonging to this group, K. blakei sp. nov., K. brisae sp. nov., K. goytaca sp. nov., K. jongo sp. nov. and K. papaveroi sp. nov. are described here. Kirkegaardia baptisteae-tesselata includes species that lack thoracic parapodia elevated and mid-dorsal thoracic groove, although a dorsal ridge is sometimes developed. In the pre-setigerous region dorsal ridges and rings are present or absent. Most species in this group have neurosetae denticulated, and notosetae capillaries of other types. This study adds K. helenae sp. nov., K. medusa sp. nov., K. nupem sp. nov. and K. zafirae sp. nov. to the latter species group. In addition, two new records are provided for K. hampsoni. A key to cirratulid polychaete species reported from Brazilian waters is provided.
Topics: Animal Distribution; Animals; Annelida; Brazil; Lepidoptera; Mantodea; Polychaeta
PubMed: 35537464
DOI: 10.1371/journal.pone.0265336 -
Proceedings of the National Academy of... Feb 2021Living systems at all scales aggregate in large numbers for a variety of functions including mating, predation, and survival. The majority of such systems consist of...
Living systems at all scales aggregate in large numbers for a variety of functions including mating, predation, and survival. The majority of such systems consist of unconnected individuals that collectively flock, school, or swarm. However, some aggregations involve physically entangled individuals, which can confer emergent mechanofunctional material properties to the collective. Here, we study in laboratory experiments and rationalize in theoretical and robophysical models the dynamics of physically entangled and motile self-assemblies of 1-cm-long California blackworms (, Annelida: Clitellata: Lumbriculidae). Thousands of individual worms form braids with their long, slender, and flexible bodies to make a three-dimensional, soft, and shape-shifting "blob." The blob behaves as a living material capable of mitigating damage and assault from environmental stresses through dynamic shape transformations, including minimizing surface area for survival against desiccation and enabling transport (negative thermotaxis) from hazardous environments (like heat). We specifically focus on the locomotion of the blob to understand how an amorphous entangled ball of worms can break symmetry to move across a substrate. We hypothesize that the collective blob displays rudimentary differentiation of function across itself, which when combined with entanglement dynamics facilitates directed persistent blob locomotion. To test this, we develop a robophysical model of the worm blobs, which displays emergent locomotion in the collective without sophisticated control or programming of any individual robot. The emergent dynamics of the living functional blob and robophysical model can inform the design of additional classes of adaptive mechanofunctional living materials and emergent robotics.
Topics: Animals; Annelida; Desiccation; Imaging, Three-Dimensional; Locomotion; Models, Biological; Phototaxis; Robotics; Stress, Physiological; Taxis Response; Temperature; Volatilization; Water
PubMed: 33547237
DOI: 10.1073/pnas.2010542118 -
Nature Communications Apr 2022Animal development is classified as conditional or autonomous based on whether cell fates are specified through inductive signals or maternal determinants, respectively....
Animal development is classified as conditional or autonomous based on whether cell fates are specified through inductive signals or maternal determinants, respectively. Yet how these two major developmental modes evolved remains unclear. During spiral cleavage-a stereotypic embryogenesis ancestral to 15 invertebrate groups, including molluscs and annelids-most lineages specify cell fates conditionally, while some define the primary axial fates autonomously. To identify the mechanisms driving this change, we study Owenia fusiformis, an early-branching, conditional annelid. In Owenia, ERK1/2-mediated FGF receptor signalling specifies the endomesodermal progenitor. This cell likely acts as an organiser, inducing mesodermal and posterodorsal fates in neighbouring cells and repressing anteriorising signals. The organising role of ERK1/2 in Owenia is shared with molluscs, but not with autonomous annelids. Together, these findings suggest that conditional specification of an ERK1/2 embryonic organiser is ancestral in spiral cleavage and was repeatedly lost in annelid lineages with autonomous development.
Topics: Animals; Annelida; Cell Differentiation; MAP Kinase Signaling System; Mesoderm; Mollusca; Polychaeta
PubMed: 35484126
DOI: 10.1038/s41467-022-30004-4 -
Cells Dec 2021Aquaporins (AQPs) are a family of membrane channels facilitating diffusion of water and small solutes into and out of cells. Despite their biological relevance in...
Aquaporins (AQPs) are a family of membrane channels facilitating diffusion of water and small solutes into and out of cells. Despite their biological relevance in osmoregulation and ubiquitous distribution throughout metazoans, the presence of AQPs in annelids has been poorly investigated. Here, we searched and annotated sequences in public genomes and transcriptomes of annelids, inferred their evolutionary relationships through phylogenetic analyses and discussed their putative physiological relevance. We identified a total of 401 sequences in 27 annelid species, including 367 sequences previously unrecognized as . Similar to vertebrates, phylogenetic tree reconstructions clustered these annelid in four clades: AQP1-like, AQP3-like, AQP8-like and AQP11-like. We found no clear indication of the existence of paralogs exclusive to annelids; however, several gene duplications seem to have occurred in the ancestors of some Sedentaria annelid families, mainly in the AQP1-like clade. Three of the six annotated in , an estuarine annelid showing high salinity tolerance, were validated by RT-PCR sequencing, and their similarity to human AQPs was investigated at the level of "key" conserved residues and predicted three-dimensional structure. Our results suggest a diversification of the structures and functions of AQPs in Annelida comparable to that observed in other taxa.
Topics: Amino Acid Sequence; Animals; Annelida; Aquaporins; Evolution, Molecular; Humans; Models, Molecular; Molecular Sequence Annotation; Phylogeny; RNA, Messenger; Transcriptome
PubMed: 34944070
DOI: 10.3390/cells10123562