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58 pages, 25268 KiB

Open AccessEditor’s ChoiceArticle

Interstitial Annelida

by Katrine Worsaae, Alexandra Kerbl, Maikon Di Domenico, Brett C. Gonzalez, Nicolas Bekkouche and Alejandro Martínez

Diversity 2021, 13(2), 77; https://doi.org/10.3390/d13020077 - 12 Feb 2021

Cited by 15 | Viewed by 5802

Abstract

Members of the following marine annelid families are found almost exclusively in the interstitial environment and are highly adapted to move between sand grains, relying mostly on ciliary locomotion: Apharyngtidae n. fam., Dinophilidae, Diurodrilidae, Nerillidae, Lobatocerebridae, Parergodrilidae, Polygordiidae, Protodrilidae, Protodriloididae, Psammodrilidae and Saccocirridae. [...] Read more.

Members of the following marine annelid families are found almost exclusively in the interstitial environment and are highly adapted to move between sand grains, relying mostly on ciliary locomotion: Apharyngtidae n. fam., Dinophilidae, Diurodrilidae, Nerillidae, Lobatocerebridae, Parergodrilidae, Polygordiidae, Protodrilidae, Protodriloididae, Psammodrilidae and Saccocirridae. This article provides a review of the evolution, systematics, and diversity of these families, with the exception of Parergodrilidae, which was detailed in the review of Orbiniida by Meca, Zhadan, and Struck within this Special Issue. While several of the discussed families have previously only been known by a few described species, recent surveys inclusive of molecular approaches have increased the number of species, showing that all of the aforementioned families exhibit a high degree of cryptic diversity shadowed by a limited number of recognizable morphological traits. This is a challenge for studies of the evolution, taxonomy, and diversity of interstitial families as well as for their identification and incorporation into ecological surveys. By compiling a comprehensive and updated review on these interstitial families, we hope to promote new studies on their intriguing evolutionary histories, adapted life forms and high and hidden diversity. Full article

(This article belongs to the Special Issue Systematics and Diversity of Annelids)

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Review

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47 pages, 5842 KiB

Open AccessReview

Still Digging: Advances and Perspectives in the Study of the Diversity of Several Sedentarian Annelid Families

by Maël Grosse, Anna Zhadan, Joachim Langeneck, Dieter Fiege and Alejandro Martínez

Diversity 2021, 13(3), 132; https://doi.org/10.3390/d13030132 - 18 Mar 2021

Cited by 6 | Viewed by 4076

Abstract

Sedentarian annelids are a diverse and heterogeneous group of marine worms representing more than 8600 species gathered in ca. 43 families. The attention brought to these organisms is unevenly distributed among these families, and the knowledge about them sometimes scarce. We review here [...] Read more.

Sedentarian annelids are a diverse and heterogeneous group of marine worms representing more than 8600 species gathered in ca. 43 families. The attention brought to these organisms is unevenly distributed among these families, and the knowledge about them sometimes scarce. We review here the current knowledge about the families Acrocirridae, Cirratulidae (including Ctenodrilidae), Cossuridae, Longosomatidae, Paraonidae, and Sternaspidae in terms of biodiversity as well as the evolution of the taxonomy and systematics of each group. We present the challenges faced when studying these organisms and compare methodologies across groups and perspectives in future research. Full article

(This article belongs to the Special Issue Systematics and Diversity of Annelids)

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65 pages, 14488 KiB

Open AccessEditor’s ChoiceReview

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

by Daniel Martin, Maria Teresa Aguado, María-Ana Fernández Álamo, Temir Alanovich Britayev, Markus Böggemann, María Capa, Sarah Faulwetter, Marcelo Veronesi Fukuda, Conrad Helm, Monica Angelica Varella Petti, Ascensão Ravara and Marcos A. L. Teixeira

Diversity 2021, 13(3), 131; https://doi.org/10.3390/d13030131 - 17 Mar 2021

Cited by 18 | Viewed by 13394

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Special Issue Systematics and Diversity of Annelids)

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73 pages, 8291 KiB

Open AccessEditor’s ChoiceReview

Fanworms: Yesterday, Today and Tomorrow

by María Capa, Elena Kupriyanova, João Miguel de Matos Nogueira, Andreas Bick and María Ana Tovar-Hernández

Diversity 2021, 13(3), 130; https://doi.org/10.3390/d13030130 - 17 Mar 2021

Cited by 20 | Viewed by 8200

Abstract

Sabellida Levinsen, 1883 is a large morphologically uniform group of sedentary annelids commonly known as fanworms. These annelids live in tubes made either of calcareous carbonate or mucus with agglutinated sediment. They share the presence of an anterior crown consisting of radioles and [...] Read more.

Sabellida Levinsen, 1883 is a large morphologically uniform group of sedentary annelids commonly known as fanworms. These annelids live in tubes made either of calcareous carbonate or mucus with agglutinated sediment. They share the presence of an anterior crown consisting of radioles and the division of the body into thorax and abdomen marked by a chaetal and fecal groove inversion. This study synthesises the current state of knowledge about the diversity of fanworms in the broad sense (morphological, ecological, species richness), the species occurrences in the different biogeographic regions, highlights latest surveys, provides guidelines for identification of members of each group, and describe novel methodologies for species delimitation. As some members of this group are well-known introduced pests, we address information about these species and their current invasive status. In addition, an overview of the current evolutionary hypothesis and history of the classification of members of Sabellida is presented. The main aim of this review is to highlight the knowledge gaps to stimulate research in those directions. Full article

(This article belongs to the Special Issue Systematics and Diversity of Annelids)

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14 pages, 2569 KiB

Open AccessEditor’s ChoiceReview

Annelid Diversity: Historical Overview and Future Perspectives

by María Capa and Pat Hutchings

Diversity 2021, 13(3), 129; https://doi.org/10.3390/d13030129 - 17 Mar 2021

Cited by 21 | Viewed by 16133

Abstract

Annelida is a ubiquitous, common and diverse group of organisms, found in terrestrial, fresh waters and marine environments. Despite the large efforts put into resolving the evolutionary relationships of these and other Lophotrochozoa, and the delineation of the basal nodes within the group, [...] Read more.

Annelida is a ubiquitous, common and diverse group of organisms, found in terrestrial, fresh waters and marine environments. Despite the large efforts put into resolving the evolutionary relationships of these and other Lophotrochozoa, and the delineation of the basal nodes within the group, these are still unanswered. Annelida holds an enormous diversity of forms and biological strategies alongside a large number of species, following Arthropoda, Mollusca, Vertebrata and perhaps Platyhelminthes, among the species most rich in phyla within Metazoa. The number of currently accepted annelid species changes rapidly when taxonomic groups are revised due to synonymies and descriptions of a new species. The group is also experiencing a recent increase in species numbers as a consequence of the use of molecular taxonomy methods, which allows the delineation of the entities within species complexes. This review aims at succinctly reviewing the state-of-the-art of annelid diversity and summarizing the main systematic revisions carried out in the group. Moreover, it should be considered as the introduction to the papers that form this Special Issue on Systematics and Biodiversity of Annelids. Full article

(This article belongs to the Special Issue Systematics and Diversity of Annelids)

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23 pages, 4037 KiB

Open AccessEditor’s ChoiceReview

Annelids in Extreme Aquatic Environments: Diversity, Adaptations and Evolution

by Christopher J. Glasby, Christer Erséus and Patrick Martin

Diversity 2021, 13(2), 98; https://doi.org/10.3390/d13020098 - 23 Feb 2021

Cited by 24 | Viewed by 12698

Abstract

We review the variety of morphological, physiological and behavioral modifications that annelids have acquired to cope with environments either unsuitable for, or on the limits of, survival for most animals. We focus on polychaetes (excluding sipunculans and echiurans) and clitellates (oligochaetes and leeches) [...] Read more.

We review the variety of morphological, physiological and behavioral modifications that annelids have acquired to cope with environments either unsuitable for, or on the limits of, survival for most animals. We focus on polychaetes (excluding sipunculans and echiurans) and clitellates (oligochaetes and leeches) and source information mostly from the primary literature. We identified many modifications common to both polychaetes and clitellates, and others that are specific to one or the other group. For example, certain land-adapted polychaetes show reduction in nuchal organs, epidermal ciliation and receptor cells, and other coastal polychaetes use adhesive glands and glue-reinforced tubes to maintain position in surf zones, while oligochaetes, with their simple body plans, appear to be ‘pre-adapted’ to life underground. Modifications common to both groups include the ability to construct protective cocoons, make cryoprotective substances such as antifreeze and heat shock proteins, develop gills, transform their bodies into a home for symbiotic chemoautotrophic bacteria, metabolize contaminants, and display avoidance behaviors. Convergent evolution in both directions has enabled annelids to transition from salt water to freshwater, sea to land via beaches, freshwater to soil, and surface water to subterranean water. A superficially simple worm-like body and a mostly benthic/burrowing lifestyle has facilitated radiation into every conceivable environment, making annelids among the most common and diverse animal groups on the planet. Full article

(This article belongs to the Special Issue Systematics and Diversity of Annelids)

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34 pages, 6960 KiB

Open AccessReview

On the Systematics and Biodiversity of the Opheliidae and Scalibregmatidae

by Julio Parapar, Alejandro Martínez and Juan Moreira

Diversity 2021, 13(2), 87; https://doi.org/10.3390/d13020087 - 18 Feb 2021

Cited by 8 | Viewed by 3987

Abstract

In this paper we review the systematics, diversity, and ecology of two related annelid families: Opheliidae Malmgren, 1867 and Scalibregmatidae Malmgren, 1867. Opheliids are deposit-feeders and that are mainly found as burrowers in sandy sediments. Morphologically, opheliids are characterized by the smooth cuticle, [...] Read more.

In this paper we review the systematics, diversity, and ecology of two related annelid families: Opheliidae Malmgren, 1867 and Scalibregmatidae Malmgren, 1867. Opheliids are deposit-feeders and that are mainly found as burrowers in sandy sediments. Morphologically, opheliids are characterized by the smooth cuticle, as well as the presence of a conspicuous ventral groove, reduced parapodia, and a tubular-shaped structure often projecting from the posterior end. Scalibregmatids are also deposit-feeders, but compared to opheliids, they have a characteristic arenicoliform body, a T-shaped anterior end and a glandular, reticulated epidermis. For each family, we summarize the available information about the evolutionary relationships, taxonomic history, geographical distribution, ecological preferences and diversity of life strategies along with the techniques most commonly used for their study. By highlighting the main gaps in knowledge on each of these topics, this review ultimately aims at stimulating further research into members of these two families in the future. Full article

(This article belongs to the Special Issue Systematics and Diversity of Annelids)

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54 pages, 7357 KiB

Open AccessFeature PaperEditor’s ChoiceReview

The Current State of Eunicida (Annelida) Systematics and Biodiversity

by Joana Zanol, Luis F. Carrera-Parra, Tatiana Menchini Steiner, Antonia Cecilia Z. Amaral, Helena Wiklund, Ascensão Ravara and Nataliya Budaeva

Diversity 2021, 13(2), 74; https://doi.org/10.3390/d13020074 - 09 Feb 2021

Cited by 24 | Viewed by 8710

Abstract

In this study, we analyze the current state of knowledge on extant Eunicida systematics, morphology, feeding, life history, habitat, ecology, distribution patterns, local diversity and exploitation. Eunicida is an order of Errantia annelids characterized by the presence of ventral mandibles and dorsal maxillae [...] Read more.

In this study, we analyze the current state of knowledge on extant Eunicida systematics, morphology, feeding, life history, habitat, ecology, distribution patterns, local diversity and exploitation. Eunicida is an order of Errantia annelids characterized by the presence of ventral mandibles and dorsal maxillae in a ventral muscularized pharynx. The origin of Eunicida dates back to the late Cambrian, and the peaks of jaw morphology diversity and number of families are in the Ordovician. Species richness is heterogeneous among the seven recent families, with more than half of the valid species belonging to the Eunicidae + Onuphidae clade, one of the latest clades to diverge. Eunicidans inhabit soft and hard substrates from intertidal to deep waters in all oceans. The few freshwater species are restricted to Histriobdellidae, a family exclusively commensal/parasite of crustaceans. The reproductive biology, development and ecology of most families are poorly known and the information available suggests low dispersal ability. However, all families have records of widely distributed species. Scrutiny of these wide distributions has often revealed the presence of exotic species or more than one species. The exploration of the deep-sea and of new habitats has led to recent descriptions of new species. Furthermore, the revision of type specimens, the examination of new morphological features and the use of molecular data have revealed hidden biodiversity under unjustified synonyms, poor understanding of morphological features and incomplete descriptions. Molecular studies are still very few or nonexistent for the families Histriobdellidae, Hartmaniellidae, Lumbrineridae and Oenonidae. The integration of new methodologies for morphological and molecular study, along with information on biological and ecological traits appears to be the path to improve the knowledge on the diversity of Eunicida. Full article

(This article belongs to the Special Issue Systematics and Diversity of Annelids)

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32 pages, 8370 KiB

Open AccessEditor’s ChoiceReview

The Terebelliformia-Recent Developments and Future Directions

by Pat Hutchings, Orlemir Carrerette, João M. M. Nogueira, Stephane Hourdez and Nicolas Lavesque

Diversity 2021, 13(2), 60; https://doi.org/10.3390/d13020060 - 03 Feb 2021

Cited by 9 | Viewed by 4301

Abstract

Terebelliformia comprises a large group of sedentary polychaetes which live from the intertidal to the deep sea. The majority live in tubes and are selective deposit feeders. This study synthesises the current knowledge of this group, including their distribution, in the different biogeographic [...] Read more.

Terebelliformia comprises a large group of sedentary polychaetes which live from the intertidal to the deep sea. The majority live in tubes and are selective deposit feeders. This study synthesises the current knowledge of this group, including their distribution, in the different biogeographic regions. We highlight the new methodologies being used to describe them and the resolution of species complexes occurring in the group. The main aim of this review is to highlight the knowledge gaps and to stimulate research in those directions, which will allow for knowledge of their distribution and abundances to be used by ecologists and managers. Full article

(This article belongs to the Special Issue Systematics and Diversity of Annelids)

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15 pages, 2571 KiB

Open AccessFeature PaperEditor’s ChoiceReview

How Many Sipunculan Species Are Hiding in Our Oceans?

by Anja Schulze and Gisele Y. Kawauchi

Diversity 2021, 13(2), 43; https://doi.org/10.3390/d13020043 - 24 Jan 2021

Cited by 15 | Viewed by 7924

Abstract

Sipuncula, long considered a separate phylum, are now commonly included in the Annelida based on phylogenomic analyses. The sipunculan body consists of an unsegmented trunk and a retractable introvert, usually with a set of tentacles at its anterior end. Unlike other annelids, they [...] Read more.

Sipuncula, long considered a separate phylum, are now commonly included in the Annelida based on phylogenomic analyses. The sipunculan body consists of an unsegmented trunk and a retractable introvert, usually with a set of tentacles at its anterior end. Unlike other annelids, they have no chaetae, but the introvert is often adorned with proteinaceous hooks that can be important taxonomic characters. Other external taxonomic characters include the tentacles (number, shape and arrangement), body papillae and, in some cases, hardened shields, as well as length ratios. Many species require dissection for correct identification to reveal internal characteristics, such as introvert retractor muscles, nephridia and contractile vessels. Here we summarize the state of the current knowledge of species diversity in sipunculans. We emphasize molecular studies, conducted over the past two decades, that have revealed multiple complexes of cryptic or pseudocryptic species. It has become obvious that diversity is significantly higher than the current taxonomic scheme accounts for, but formal species descriptions are lagging behind. Although the major branches in the sipunculan phylogeny have become increasingly consolidated, the internal relationships within most branches are still in flux. Full article

(This article belongs to the Special Issue Systematics and Diversity of Annelids)

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44 pages, 17099 KiB

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On the Systematics and Biodiversity of the Palaeoannelida

by Julio Parapar, Kate Mortimer, María Capa and Juan Moreira

Diversity 2021, 13(2), 41; https://doi.org/10.3390/d13020041 - 21 Jan 2021

Cited by 10 | Viewed by 4434

Abstract

Palaeoannelida Weigert and Bleidorn, 2016 is an old clade branching off at the base of the Annelida radiation. It includes two morphologically and ecological divergent groups of sedentary burrowers and tube-dwellers: Magelonidae Cunningham and Ramage, 1888, and Oweniidae Rioja, 1917. Magelonids are characterised [...] Read more.

Palaeoannelida Weigert and Bleidorn, 2016 is an old clade branching off at the base of the Annelida radiation. It includes two morphologically and ecological divergent groups of sedentary burrowers and tube-dwellers: Magelonidae Cunningham and Ramage, 1888, and Oweniidae Rioja, 1917. Magelonids are characterised by a flattened, shovel-shaped prostomium and a pair of ventral papillated palps. Oweniids have simplified bodies lacking parapodia or appendages and are easily distinguished by the presence of oval patches of packed uncini, each with two distal curved teeth. The present review aims to summarise available information about the diversity of forms and life strategies displayed in the group, providing some guidelines for species identification and the techniques commonly used for their study. In addition, the assumed geographic distributions of some taxa are critically discussed. A brief introduction about the evolutionary relationships, systematics, and taxonomic history is given for both Magelonidae and Oweniidae. The motivation of this review is to highlight the main knowledge gaps from a taxonomic, methodological, and geographic perspective, aiming at stimulating further research into members of this clade. Full article

(This article belongs to the Special Issue Systematics and Diversity of Annelids)

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13 pages, 549 KiB

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Cryptic Clitellata: Molecular Species Delimitation of Clitellate Worms (Annelida): An Overview

by Svante Martinsson and Christer Erséus

Diversity 2021, 13(2), 36; https://doi.org/10.3390/d13020036 - 20 Jan 2021

Cited by 16 | Viewed by 4172

Abstract

Methods for species delimitation using molecular data have developed greatly and have become a staple in systematic studies of clitellate worms. Here we give a historical overview of the data and methods used to delimit clitellates from the mid-1970s to today. We also [...] Read more.

Methods for species delimitation using molecular data have developed greatly and have become a staple in systematic studies of clitellate worms. Here we give a historical overview of the data and methods used to delimit clitellates from the mid-1970s to today. We also discuss the taxonomical treatment of the cryptic species, including the recommendation that cryptic species, as far as possible, should be described and named. Finally, we discuss the prospects and further development of the field. Full article

(This article belongs to the Special Issue Systematics and Diversity of Annelids)

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31 pages, 18530 KiB

Open AccessEditor’s ChoiceReview

The Early Branching Group of Orbiniida Sensu Struck et al., 2015: Parergodrilidae and Orbiniidae

by Miguel A. Meca, Anna Zhadan and Torsten H. Struck

Diversity 2021, 13(1), 29; https://doi.org/10.3390/d13010029 - 13 Jan 2021

Cited by 5 | Viewed by 3582

Abstract

This review addresses the state of the art of the systematics and the improvements in the biology, ecology and species diversity of the two annelid taxa Parergodrilidae and Orbiniidae, the early branching group of Orbiniida sensu Struck et al., 2015 according to molecular [...] Read more.

This review addresses the state of the art of the systematics and the improvements in the biology, ecology and species diversity of the two annelid taxa Parergodrilidae and Orbiniidae, the early branching group of Orbiniida sensu Struck et al., 2015 according to molecular studies. An effort to identify gaps of knowledge is given to understand the distribution, dispersal and the diversity Parergodrilidae and Orbiniidae hold, as well as to give several directions for future research. Parergodrilidae is a taxon of interstitial annelids constituted by the terrestrial Parergodrilus heideri (monotypic genus up to date), reported throughout Europe but also in Korea and North America, and the genus Stygocapitella, which includes eleven species from the upper shore of sandy beaches distributed along Europe and other regions of the world. Orbiniidae contains more than 200 described species spread over 20 valid genera, varying in size from a few millimeters up to 30 cm, distributed globally and living in a wide variety of soft bottoms. Improving the knowledge on these two sister-taxa is crucial for the understanding of the evolution to interstitial forms by progenesis in Annelida. Full article

(This article belongs to the Special Issue Systematics and Diversity of Annelids)

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