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42 pages, 20402 KiB

Open AccessArticle

First Investigation of the Marine Gastrotrich Fauna from the Waters of North Tunisia, with the Description of a New Species of Halichaetonotus (Gastrotricha, Chaetonotida)

by Aicha Souid, Mehrez Gammoudi, Francesco Saponi, M’hamed El Cafsi and M. Antonio Todaro

Diversity 2025, 17(1), 17; https://doi.org/10.3390/d17010017 - 27 Dec 2024

Viewed by 778

Abstract

Gastrotrichs (hairy bellies) are microscopic, acoelomate worms that live in freshwater and marine environments and represent one of the significant components of the meiobenthic communities. There are over 520 marine species, and several of them are also found in the Mediterranean Sea. However, data on the gastrotrich fauna from Tunisia is negligible, with nearly zero annotated records. We have initiated a series of investigations along the Tunisian shores to address this gap. Herein, we report data from four collecting sites on the northern Tunisian coastline. Sandy samples from 2 m water depth yielded 21 species, 11 in the order Macrodasyida and 10 in Chaetonotida. One chaetonotidan new to science is formally described, while morphometric data and photomicrographs are provided for all the others. Incidentally, we report on the longest gastrotrich ever found. Information about the microhabitat’s characteristics, including the water’s salinity and temperature and granulometric parameters of the sediment, are also reported. Finally, we provide information on Tunisian species previously discovered by our team and involved in phylogenetic studies for which morphological data and details about their findings have never been published. We explicitly address and correct the errors in GenBank concerning the attribution of gene sequences for these species. Full article

(This article belongs to the Special Issue 2024 Feature Papers by Diversity’s Editorial Board Members)

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23 pages, 4354 KiB

Open AccessArticle

Status of the Italian Freshwater Gastrotricha Biodiversity, with the Creation of an Interactive GIS-Based Web Map

by Francesco Saponi and M. Antonio Todaro

Diversity 2024, 16(1), 17; https://doi.org/10.3390/d16010017 - 25 Dec 2023

Cited by 7 | Viewed by 2360

Abstract

Gastrotricha are microscopic benthic animals found in almost all water bodies. To date, over 890 species distributed in 71 genera, 18 families, and two orders are known. There are 376 freshwater species, and several are also found in Italy; however, a compendium of the studies carried out so far, and a georeferenced distribution of the species, still need to be provided. This project summarizes information about the diversity and geographic distribution of Italian gastrotrichs. Diversity data, acquired over 239 years, were reviewed and corrected based on taxonomic and nomenclatural updates and, in addition to distribution information, were organized into a data matrix valuable for statistical analysis. The data were fed into geographic information system software to understand the overall figures more easily. The results indicated that Italy is one of the best-known countries regarding freshwater gastrotrichs. With 92 species in 17 genera and three families from 61 investigated localities, Italy counts 17 type localities and 19 endemic species. Despite this high biodiversity, many Italian regions still need to be investigated, and should, therefore, be the focus of future research. The implementation of a web-mapping plugin enabled the creation of interactive maps for an easy and modern method for sharing the work done, and the information acquired. Full article

(This article belongs to the Special Issue Diversity in 2023)

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13 pages, 6194 KiB

Open AccessArticle

Confocal Laser Scanning Microscopy Applied to a New Species Helps Understand the Functioning of the Reproductive Apparatus in Stylet-Bearing Urodasys (Gastrotricha: Macrodasyida)

by Agata Cesaretti, Francesca Leasi and M. Antonio Todaro

Water 2023, 15(6), 1106; https://doi.org/10.3390/w15061106 - 14 Mar 2023

Cited by 5 | Viewed by 2433

Abstract

Gastrotrichs are highly diverse and abundant in all aquatic ecosystems; however, they are often overlooked. During a biodiversity survey in Sardinia (Italy), a new species of gastrotrich herein described was discovered. Specimens of Urodasys bifidostylis sp. nov. were found in sandy sediments from two submarine caves. Using an integrative approach of traditional light (DIC) and high-resolution (CLSM) microscopies, we herein reveal, for the first time, the fine structure and function of the reproductive organ in an Urodasys representative. This is particularly relevant considering the complex reproductive organs and strategies of this group. Results allow comparisons between the reproductive apparatus and sperm transfer modalities in Urodasys and the closely related genus Macrodasys. One similarity is that both groups transfer male gametes in packets, suggesting the production of spermatophores to be a common phenomenon in Gastrotricha. Unique to Urodasys is the ability of multiple and consecutive copulations and sperm transfers and, differently than Macrodasys, the transfer of sperms unlikely occurs simultaneously between the two hermaphroditic partners. These findings provide new insights into the reproductive strategies of Urodasys and are expected to advance future studies on the evolution of reproductive strategies and the rise of interspecific reproductive barriers in interstitial meiofauna. Full article

(This article belongs to the Special Issue Research on the Aquatic Species Biodiversity and Morphology)

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14 pages, 4822 KiB

Open AccessArticle

A New Species of Paraturbanella Remane, 1927 (Gastrotricha, Macrodasyida) from the Brazilian Coast, and the Molecular Phylogeny of Turbanellidae Remane, 1926

by Ariane Campos, M. Antonio Todaro and André Rinaldo Senna Garraffoni

Diversity 2020, 12(2), 42; https://doi.org/10.3390/d12020042 - 21 Jan 2020

Cited by 7 | Viewed by 3460

Abstract

The family Turbanellidae includes Paraturbanella and five other genera. Despite the fact that the monophyly of these genera were not satisfactorily tested, species belonging to the genus Paraturbanella are distinguished from turbanellids by sharing a peculiar group of tubes on the ventrolateral side of the anterior pharyngeal region known as “dohrni” tubes. In this study, Paraturbanella tricaudata species nova (sp. nov.) from the intertidal zone of a sandy beach in Trindade (Rio de Janeiro State) and the sublittoral sand of Prumirim Island (São Paulo State), Brazil, is described. The new species can be distinguished from all other Paraturbanella species by the presence of three caudal cones (one medial and two laterals to it) and peculiar arrangement of the male system. This is the first description of a Paraturbanella species from Brazil and the third registered from the Southern Hemisphere (as opposed to 19 species in the Northern Hemisphere); thus, knowledge of marine gastrotrichs biodiversity in this region is far from satisfactory. Full article

(This article belongs to the Special Issue Meiofauna Biodiversity and Ecology)

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25 pages, 10283 KiB

Open AccessArticle

An Introduction to the Study of Gastrotricha, with a Taxonomic Key to Families and Genera of the Group

by M. Antonio Todaro, Jeffrey Alejandro Sibaja-Cordero, Oscar A. Segura-Bermúdez, Génesis Coto-Delgado, Nathalie Goebel-Otárola, Juan D. Barquero, Mariana Cullell-Delgado and Matteo Dal Zotto

Diversity 2019, 11(7), 117; https://doi.org/10.3390/d11070117 - 23 Jul 2019

Cited by 35 | Viewed by 11781

Abstract

Gastrotricha is a group of meiofaunal-sized, free-living invertebrates present in all aquatic ecosystems. The phylum includes over 860 species globally, of which 505 nominal species have been recorded in marine sandy sediments; another 355 taxa inhabit the freshwater environments, where they are recurrent members of the periphyton and epibenthos, and, to a lesser degree, of the plankton and interstitial fauna. Gastrotrichs are part of the permanent meiofauna and, in general, they rank among the top five groups for abundance within meiobenthic assemblages. The diversity, abundance, and ubiquity of Gastrotricha allow us to suppose an important role for these animals in aquatic ecosystems; however, ecological studies to prove this idea have been comparatively very few. This is mainly because the small size and transparency of their bodies make gastrotrichs difficult to discover in benthic samples; moreover, their contractility and fragility make their handling and morphological survey of the specimens rather difficult. Here we offer an overview, describe the basic techniques used to study these animals, and provide a key to known genera in an attempt to promote easy identification and to increase the number of researchers who may be interested in conducting studies on this understudied ecological group of microscopic organisms. Full article

(This article belongs to the Special Issue Meiofauna Biodiversity and Ecology)

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17 pages, 3093 KiB

Open AccessFeature PaperArticle

Evolutionary Implications of the microRNA- and piRNA Complement of Lepidodermella squamata (Gastrotricha)

by Bastian Fromm, Juan Pablo Tosar, Felipe Aguilera, Marc R. Friedländer, Lutz Bachmann and Andreas Hejnol

Non-Coding RNA 2019, 5(1), 19; https://doi.org/10.3390/ncrna5010019 - 22 Feb 2019

Cited by 9 | Viewed by 5386

Abstract

Gastrotrichs—’hairy bellies’—are microscopic free-living animals inhabiting marine and freshwater habitats. Based on morphological and early molecular analyses, gastrotrichs were placed close to nematodes, but recent phylogenomic analyses have suggested their close relationship to flatworms (Platyhelminthes) within Spiralia. Small non-coding RNA data on e.g., microRNAs (miRNAs) and PIWI-interacting RNAs (piRNA) may help to resolve this long-standing question. MiRNAs are short post-transcriptional gene regulators that together with piRNAs play key roles in development. In a ‘multi-omics’ approach we here used small-RNA sequencing, available transcriptome and genomic data to unravel the miRNA- and piRNA complements along with the RNAi (RNA interference) protein machinery of Lepidodermella squamata (Gastrotricha, Chaetonotida). We identified 52 miRNA genes representing 35 highly conserved miRNA families specific to Eumetazoa, Bilateria, Protostomia, and Spiralia, respectively, with overall high similarities to platyhelminth miRNA complements. In addition, we found four large piRNA clusters that also resemble flatworm piRNAs but not those earlier described for nematodes. Congruently, transcriptomic annotation revealed that the Lepidodermella protein machinery is highly similar to flatworms, too. Taken together, miRNA, piRNA, and protein data support a close relationship of gastrotrichs and flatworms. Full article

(This article belongs to the Special Issue Non-Coding RNAs, from an Evolutionary Perspective)

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