| 1. |
- Jondelius, Ulf, 1961-, et al.
(författare)
-
Acoelomorpha
- 2020. - 1
-
Ingår i: Guide to the identification of Marine Meiofauna. - München : Ulf Jondelius. - 9783899372441 ; , s. 44-53
-
Bokkapitel (refereegranskat)
|
|
| 2. |
- Jörger, Katharina, et al.
(författare)
-
MEIOZORES 2019 - EXPLORING THE MARINE MEIOFAUNA OF THE AZORES
- 2021
-
Ingår i: AÇOREANA. ; , s. 17-41
-
Tidskriftsartikel (refereegranskat)abstract
- In July 2019 an international team of 39 senior and junior researchers from ninecountries met at the University of the Azores in Ponta Delgada, São Miguel for a 10-daysworkshop/ summer school to explore the meiofaunal biodiversity in marine sediments of the Azores. In total, we sampled intertidal and subtidal sediments from 54 localities on 14 major sites around São Miguel and additionally explored eight freshwater and terrestrial sites for rotifers. We sorted and investigated more than 2000 living specimens in the field, yielding approximately 180 species of soft-bodied meiofauna, representing most major clades of meiofauna with a focus on nematodes, polychaete annelids, proseriate andrhabdocoel flatworms, gastrotrichs, acoelomorphs, nemerteans, molluscs and cnidarians. Most of the encountered diversity shows similarities to the North-East Atlantic continental meiofauna, but in-depth morphological and molecular analyses are still pending. About 60 of the 180 species could not be assigned a species-level identification in the field, and nearly 15% of the total diversity is expected to be new to science and is awaiting formal description. Herein, we present an overview of the results of the workshop, providing detailed information on the sampling sites, methodology and encountered diversity, and we offer a preliminary discussion on aspects of faunal elements shared with other biogeographic regions. We highlight the most common members of the marine meiofauna of the Azores, provide preliminary diversity estimates and suggest a roadmap for future research towards a better understanding of the meiofauna in this remote archipelago.
|
|
| 3. |
- Abalde, Samuel, et al.
(författare)
-
The draft genome of the microscopic Nemertoderma westbladi sheds light on the evolution of Acoelomorpha genomes
- 2023
-
Ingår i: Frontiers in Genetics. - : Frontiers Media S.A.. - 1664-8021. ; 14
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Xenacoelomorpha is a marine clade of microscopic worms that is an important model system for understanding the evolution of key bilaterian novelties, such as the excretory system. Nevertheless, Xenacoelomorpha genomics has been restricted to a few species that either can be cultured in the lab or are centimetres long. Thus far, no genomes are available for Nemertodermatida, one of the group’s main clades and whose origin has been dated more than 400 million years ago.Methods: DNA was extracted from a single specimen and sequenced with HiFi following the PacBio Ultra-Low DNA Input protocol. After genome assembly, decontamination, and annotation, the genome quality was benchmarked using two acoel genomes and one Illumina genome as reference. The gene content of three cnidarians, three acoelomorphs, four deuterostomes, and eight protostomes was clustered in orthogroups to make inferences of gene content evolution. Finally, we focused on the genes related to the ultrafiltration excretory system to compare patterns of presence/absence and gene architecture among these clades.Results: We present the first nemertodermatid genome sequenced from a single specimen of Nemertoderma westbladi. Although genome contiguity remains challenging (N50: 60 kb), it is very complete (BUSCO: 80.2%, Metazoa; 88.6%, Eukaryota) and the quality of the annotation allows fine-detail analyses of genome evolution. Acoelomorph genomes seem to be relatively conserved in terms of the percentage of repeats, number of genes, number of exons per gene and intron size. In addition, a high fraction of genes present in both protostomes and deuterostomes are absent in Acoelomorpha. Interestingly, we show that all genes related to the excretory system are present in Xenacoelomorpha except Osr, a key element in the development of these organs and whose acquisition seems to be interconnected with the origin of the specialised excretory system.Conclusion: Overall, these analyses highlight the potential of the Ultra-Low Input DNA protocol and HiFi to generate high-quality genomes from single animals, even for relatively large genomes, making it a feasible option for sequencing challenging taxa, which will be an exciting resource for comparative genomics analyses.
|
|
| 4. |
- Atherton, Sarah, et al.
(författare)
-
Diversity in the family Isodiametridae (Acoela) : New species bring back old problems
- 2022
-
Ingår i: Zootaxa. - : Magnolia Press. - 1175-5326 .- 1175-5334. ; 5169:5, s. 401-424
-
Tidskriftsartikel (refereegranskat)abstract
- Eight new species of Isodiametridae (Acoela) are presented and phylogenetic relationships of the family using 18S and COI sequence data reconstructed. Four species of Baltalimania, two species of Praeaphanostoma and two species of Pseudoposthia are described that all can be distinguished both morphologically and through differences in the DNA sequences as supported by mPTP analysis. The addition of eight new species increases the number of nominal species of Isodiametridae worldwide by 10% and within Sweden by 31%, but also highlights several taxonomic problems. Several species are now confirmed as isodiametrids that are otherwise incongruent with the family's diagnostic characters. Generic keys are presented for Baltalimania and Praeaphanostoma.
|
|
| 5. |
- Atherton, Sarah, et al.
(författare)
-
Microstomum (Platyhelminthes, Macrostomorpha, Microstomidae) from the Swedish west coast: two new species and a population description
- 2018
-
Ingår i: European journal of taxonomy. - : Museum National D'Histoire Naturelle. - 2118-9773. ; :398, s. 1-18
-
Tidskriftsartikel (refereegranskat)abstract
- Two new species of marine Platyhelminthes, Microstomum laurae sp. nov. and Microstomum edmondi sp. nov. (Macrostomida: Microstomidae) are described from the west coast of Sweden. Microstomum laurae sp. nov. is distinguished by the following combination of characters: rounded anterior and posterior ends; presence of approximately 20 adhesive papillae on the posterior rim; paired lateral red eyespots located level with the brain; preoral gut extending anterior to brain and very small sensory pits. Microstomum edmondi sp. nov. is a protandrous hermaphrodite with a single ovary, single testis and male copulatory organ with stylet. It is characterized by a conical pointed anterior end, a blunt posterior end with numerous adhesive papillae along the rim, and large ciliary pits. The stylet is shaped as a narrow funnel with a short, arched tip. In addition, the first records of fully mature specimens of Microstomum rubromaculatum von Graff, 1882 from Fiskebäckskil and a phylogenetic analysis of Microstomum Schmidt, 1848 based on the mitochondrial cytochrome oxidase I (COI) gene are presented.
|
|
| 6. |
- Atherton, Sarah, et al.
(författare)
-
Phylogenetic assessment and systematic revision of the acoel family Isodiametridae
- 2022
-
Ingår i: Zoological Journal of the Linnean Society. - : Oxford University Press (OUP). - 0024-4082 .- 1096-3642. ; 194:3, s. 736-760
-
Tidskriftsartikel (refereegranskat)abstract
- Isodiametridae is a large family of Acoela with 22 nominal genera and nearly 100 species. Unfortunately, systematics of Isodiametridae, as it stands, is highly problematic. Genera frequently have been proposed without reference to an explicit phylogenetic hypothesis, such that the current classification system holds little or no predictive power. Many taxa do not fit with the family diagnosis, and it is increasingly difficult to determine in which taxon a new species should be described. Herein, we reconstruct the phylogenetic relationships of Acoela with a focus on Isodiametridae using both previously published and new ribosomal and mitochondrial sequence data. Our dataset comprises sequences from 45 species representing 16 of the 22 isodiametrid genera. Our results recovered a well-supported Isodiametridae, but provided further evidence that the family and several genera within require revision. We have updated the classification system of Isodiametridae to be consistent with its phylogeny, including the transference of Otocelis to Otocelididae, Postaphanostoma and Faerlea to Mecynostomidae and Alluna to Actinoposthiidae. Six other genera are placed in synonymy. We review the morphological taxonomy and provide an identification key of the genera in the revised family.
|
|
| 7. |
- Curini Galletti, Marco, et al.
(författare)
-
Contribution of soft-bodied meiofaunal taxa to Italian marine biodiversity
- 2020
-
Ingår i: The European Zoological Journal. - : Taylor & Francis. - 2475-0263. ; 87:1, s. 369-384
-
Tidskriftsartikel (refereegranskat)abstract
- Meiofauna includes an astonishing diversity of organisms, whose census is far from being complete. Most classic ecological studies have focused on hard-bodied Ecdysozoan taxa (notably Copepoda and Nematoda), whose cuticle allows determination at species-level after fixation, rather than soft-bodied, Spiralian taxa, which most often lose any diagnostic feature in fixed samples. Yet, metabarcoding studies have recently revealed a species-richness of soft-bodied taxa comparable, and in cases superior, to that of Copepoda and Nematoda together. However, given objective difficulties inherent to their study, which necessarily has to be performed on living individuals, and their limited utilisation for ecological and applicative research, taxonomic expertise on soft-bodied organisms has declined over the years, and diversity of these phyla in most areas of the world is presently completely unknown. Here we present an expert-based survey of current knowledge on the composition and distribution of soft-bodied meiofaunal taxa in Italy, with special references to the predominantly or exclusively meiobenthic phyla Gastrotricha, Gnathostomulida, Platyhelminthes, Rotifera, Xenacoelomorpha, and macrofaunal taxa with conspicuous meiofaunal representatives (Annelida, Mollusca and Nemertea). A total of 638 described species have been reported from Italian coasts; furthermore, the existence of a large number of undescribed species is mentioned. Knowledge of Annelida, Gastrotricha, and Rotifera appears particularly detailed, placing Italy among the best-known country worldwide. In contrast, knowledge of Platyhelminthes and Xenacoelomorpha appears patchy, and limited to few areas. Sampling effort has been uneven, with most species recorded from the Tyrrhenian Sea, while large sections of the Adriatic and Ionian seas have been poorly explored. Results highlight the role that Marine Biological Stations, notably the Zoological Station “Anton Dohrn” in Naples, have had in promoting the study of soft-bodied taxa in Italy.
|
|
| 8. |
- Haenel, Quiterie, et al.
(författare)
-
NGS-based biodiversity and community structure analysis of meiofaunal eukaryotes in shell sand from Hållö island, Smögen, and soft mud from Gullmarn Fjord, Sweden
- 2017
-
Ingår i: Biodiversity Data Journal. - : Oleksandr Holovachov. - 1314-2828 .- 1314-2836. ; 5
-
Tidskriftsartikel (refereegranskat)abstract
- © Haenel Q et al. Aim: The aim of this study was to assess the biodiversity and community structure of Swedish meiofaunal eukaryotes using metabarcoding. To validate the reliability of the metabarcoding approach, we compare the taxonomic resolution obtained using the mitochondrial cytochrome oxidase 1 (COI) 'mini-barcode' and nuclear 18S small ribosomal subunit (18S) V1-V2 region, with traditional morphology-based identification of Xenacoelomorpha and Nematoda. Location: 30 samples were analysed from two ecologically distinct locations along the west coast of Sweden. 18 replicate samples of coarse shell sand were collected along the northeastern side of Hållö island near Smögen, while 12 replicate samples of soft mud were collected in the Gullmarn Fjord near Lysekil.
|
|
| 9. |
- Holovachov, Oleksandr, et al.
(författare)
-
Taxonomy assignment approach determines the efficiency of identification of OTUs in marine nematodes
- 2017
-
Ingår i: Royal Society Open Science. - : The Royal Society. - 2054-5703. ; 4
-
Tidskriftsartikel (refereegranskat)abstract
- © 2017 The Authors. Precision and reliability of barcode-based biodiversity assessment can be affected at several steps during acquisition and analysis of data. Identification of operational taxonomic units (OTUs) is one of the crucial steps in the process and can be accomplished using several different approaches, namely, alignment-based, probabilistic, tree-based and phylogenybased. The number of identified sequences in the reference databases affects the precision of identification. This paper compares the identification of marine nematode OTUs using alignment-based, tree-based and phylogeny-based approaches. Because the nematode reference dataset is limited in its taxonomic scope, OTUs can only be assigned to higher taxonomic categories, families. The phylogeny-based approach using the evolutionary placement algorithm provided the largest number of positively assigned OTUs and was least affected by erroneous sequences and limitations of reference data, compared to alignment-based and tree-based approaches.
|
|
| 10. |
|
|
