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Hypotheses of some modifications occurring in larval characters of Neotrochozoa (Owenia + Enterocoela). (A) Polychaete typical trochophore represented by early larva of Polygordius sp. (Polygordiidae) (modified from FAUVEL 1959); (B) Mitraria larva represented by early larva of Owenia fusiformis (Oweniidae) (modified from FAUVEL 1959); (C) Tornaria represented by pluteus stage of ophiuromorphs (modified from WILLIAMSON 1987). Prt, typic prototroch; Spr, sinuous deuterostome-like prototroch.
Source publication
Polychaetes are metameric worms recognized for having parapodia, chaetae, and nuchal organs. Some authors have extended the Annelida to include Pogonophora, Echiura, and Clitellata. These suggestions are insufficient to generate a monophyletic group. They do not take into account two very large and important clades that in a cladistic analysis at a...
Contexts in source publication
Context 1
... larval oweniids (WILSON 1932;GARDINER 1978) represent true homologies linking Owenia with Enterocoela. Even the distinguishing character of a mouth surrounded by the prototroch in the deuterostomes proposed by WILLMER (1990) may be extended to the larvae of Owenia, as the sinuous prototroch may be interpreted as the first step in this direction (Fig. 7). Although Pogonophora (sensu lato including the Vestimentifera) do not have typical larvae, our view is consistent with older theories on the closer affinities of the Pogonophora with the Deuterostomia (IVANOV 1957(IVANOV , 1963WEBB 1969). The recent consensus for positioning the pogonophorans among the annelids (ROUSE & FAUCHALD 1995) ...
Context 2
... the radialians, resulting in a conspicuous anterior oligomeric pattern typical of lophophorates and Deuterostomia. Changes in this evolutionary line also affect the larvae. The mitraria larvae of the Owenia can be interpreted as transitional between the typical trochophore larvae of other polychaetes and the tornaria larvae of the deuterostomates (Fig. 7). This shift in morphology seems to be closely related to a gradual change from the errant, plesiotypic habit to an excavatory, and then tubiculous, fully sedentary biology. In this evolutionary sequence there is an increasing importance of the anterior part of the body (and a proportional decrease of importance of the posterior part), ...
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Annelids are a taxon of protostomes comprising more than 1–7,0–00 worldwide–013;distributed species, which can be found in marine, limnic, and terrestrial habitats (Zhang 2–011). Their phylogeny was under discussion for a long time, but recent phylogenomic analyses resulted in a solid backbone of this group (Struck et al. 2–011; Weigert et al. 2–01...
An annotated checklist of 1257 species (73 families) of Annelida from the South China Sea (SCS) is presented, including 289 species originally described from the region. The remaining extralimital records (968) are likely to represent a mixture of species complexes, misidentifications or truly widespread species, and therefore should be targets for...
Sipuncula is a small taxon of worm-like marine organisms of still uncertain phylogenetic position. Sipunculans are characterized by an unsegmented body composed of a trunk into which the anterior part, the introvert, can be withdrawn. The group has been placed at various positions within Metazoa; currently, it is either seen as sister group of a cl...
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Citations
... Several recent studies indicate the paraphyletic status of polychaetes (e.g. Rouse and Pleijel 2001, de Oliveira Almeida et al. 2003, Weigert and Bleidorn 2016 and the higher classification of Annelida has been in a constant flux over the last years (e.g. Zrzavý et al. 2001, Helm et al. 2012, Weigert and Bleidorn 2016. ...
... Reported from Greece by Koulouri et al. (2015). In the Mediterranean also reported from Spain (Desbruyères et al. 1973) and Turkey (Çınar et al. 2014). Çınar (2005) reports morphological differences in chaetal features between specimens from Cyprus and the original description of Kirkegaardia tesselata, concluding that the material might belong to an undescribed species. ...
... Notes: Questionable status. In the Mediterranean only reported from Greece (Bogdanos and Satsmadjis 1983, Bogdanos and Diapoulis 1984, NCMR 1989, Spain (Desbruyères et al. 1973) and Italy (Castelli et al. 2008) otherwise known from boreal regions and cold water areas along the French and Spanish Atlantic coasts (Dauvin et al. 2006; its presence in the Mediterranean could not yet be confirmed (Barnich and Fiege 2003). It is easily confused with Harmothoe antilopes McIntosh, 1876, a species with similar elytral structures but different notochaetae . ...
Background:
The last annotated checklist of marine polychaetes in Greece was published in 2001. Since then, global taxonomic progress, combined with many new species records for Greece, required a thorough review of the taxonomic, nomenclatural and biogeographic status of the national species list. This checklist revises the status of all extant polychaete species reported from the Greek Exclusive Economic Zone since 1832. The work was undertaken as part of the efforts on compiling a national species inventory (Greek Taxon Information System initiative) in the framework of the LifeWatchGreece Research Infrastructure.
New information:
This checklist comprises an updated and annotated inventory of polychaete species in Greek waters, compiled from literature reports, online databases, museum collections and unpublished datasets. The list provides information on 836 species-level taxa from Greece, of which 142 are considered questionable. An additional 84 species reported in the past are currently considered absent from Greece; reasons for the exclusion of each species are given. Fourteen species are reported here for the first time from Greek waters. At least 52 species in the present list constitute in fact a complex of cryptic or pseudo-cryptic species. Forty-seven species are considered non-native to the area. In addition to the species-level taxa reported in this checklist, eleven genera have been recorded from Greece with no representatives identified to species level. One replacement name is introduced. For each species, a comprehensive bibliographic list of occurrence records in Greece and the synonyms used in these publications are provided as supplementary material. Where necessary, the taxonomic, nomenclatural or biogeographic status is discussed. Finally, the findings are discussed in the wider context of Mediterranean polychaete biogeography, taxonomic practice and worldwide research progress.
... Rouse and Fauchald, 1995), although since the end of 20th century their monophyletic nature has been questioned both by morphological and molecular studies (e.g. McHugh, 1997McHugh, , 2000Purschke, 1997;Westheide, 1997), and now this idea is widely suported (Almeida et al., 2003;Bartolomaeus et al., 2005;Struck et al., 2011;Weigert and Bleidorn, 2016 among others). Traditionally, the description of an Annelid species was based mostly on external morphological body characters (e.g. head appendages, shape of parapodia, types and features of chaetae, etc.) accompanied by line drawings from stereo and light microscope examination. ...
The use of Micro-computed X-ray tomography (microCT or μCT) in the study of the anatomy of Annelids is becoming more common. Here we present a new approach to the anatomical study of six species (i.e. Phyllodoce lineata, Syllis garciai, Prionospio fallax, Branchiomma bombyx, Spirobranchus triqueter and Euclymene oerstedi) using μCT. These species represent several major annelid lineages and show therefore a wide range of morphological characteristics. Information obtained from μCT images of external and internal anatomy was compared with previous data with two major aims: 1) exploring whether quality of images allows accurate examination of annelid anatomy, and 2) evaluating the information provided by the different body characters, highlighting those with greater potential to be used for future biodiversity studies. Main conclusions obtained were: 1) the use of simple contrast staining or no staining at all provides good images that may be used in studies of comparative anatomy, 2) images of external anatomy show good definition only for macroscopic characters, 3) images of internal organs showed disparate results, being the digestive system the most promising structure, considering the quality of images and when assessing its regionalization and variability across taxa (genera, families).
... In the present study, we use the terms Polychaeta and Annelida despite their suggested polyphyletic origin (Almeida et al., 2003 andStruck et al., 2011) because the "worms" phylogeny is in disarray. Also, we consider "phylogenetically uncertain" Aeolosomatidae and other taxa for comparative and explanatory purposes. ...
The concept of ecosystem engineering has emerged decades ago and highlights the direct or indirect modulation of available resources by organisms through their biological activities. Ecosystem engineers create biogenic structures (aggregates, burrows) that may serve as habitats for other species than themselves. This chapter aims at overviewing the key role played by earthworms as ecosystem engineers through their bioturbation activities involving soil mixing as well as their influence on the decomposition and mineralization of litter by breaking down organic matter, and their influence on the gas and water exchange or nutrient transfer in the soil. Focus is made on the engineering processes and especially the formation of biogenic structures in relation to soil structure (burrows, casts) in the framework of soil function interactions, particularly in the drilosphere. Special attention is paid to soil aggregates’ fabric and new tools that may help to discriminate their origin. Finally, management and ecosystem engineer’s future challenges will be highlighted regarding soil ecosystem services in the context of ecosystem restoration.
... These gonochoristic marine worms bear a structure termed clitellum and their gonads are restricted to some segments in the anterior part. Some authors used this superficial resemblance as a support for a sister group relationship of questids and clitellates (Almeida et al. 2003). However, the homology of the clitellum-like structure in questids and the clitellum of the Clitellata has been rejected in previous studies (Giere and Erseus 1998;Giere and Riser 1981). ...
Annelida is an ecologically and morphologically diverse phylum within the Lophotrochozoa whose members occupy a wide range of environments and show diverse life styles. The phylogeny of this group comprising more than 17,000 species remained controversial for a long time. By using next-generation sequencing and phylogenomic analyses of huge data matrices, it was finally possible to reach a well-supported and resolved annelid backbone tree. Most annelid diversity is comprised in two reciprocal monophyletic groups, Sedentaria and Errantia, which are named after the predominant life style of their members. Errantia include Aciculata (Phyllodocida + Eunicida) and Protodriliformia, which is a taxon of interstitial polychaetes. Sedentaria comprise most of the polychaete families formerly classified as Canalipalpata or Scolecida, as well as the Clitellata. Six taxa branch as a basal grade outside of this major radiation: Oweniidae, Magelonidae, Chaetopteridae, Sipuncula, Amphinomida, and Lobatocerebrum. Oweniidae and Magelonidae form a monophyletic group which we name Palaeoannelida, which constitutes the sister taxon of the remaining annelids. The early splits of annelid phylogeny date back to the Cambrian. The new annelid phylogeny highlights the variability and lability of annelid body plans, and many instances of simplifications of body plan as adaptations to new life styles can be found. Therefore, annelids will be an appropriate model to understand major transitions in the evolution of Bilateria in general. Evolutionary developmental studies are one way to investigate macroevolutionary transition in annelids. We briefly summarize the state of developmental model organisms in Annelida and also propose new candidates on the background of the phylogeny.
... Giere and Erséus, 1998). More recently, Almeida and Christoff ersen (2001), Almeida et al. (2003), and Garraff oni and Amorim (2003) identify the Questidae as more closely related to Clitellata than to other polychaetes. ...
The faunistic assemblage of basal clitellates in South America presently has 2 marine species (Questa media Westheide, 1981 and Aeolosoma maritimum dubiosum Westheide & Schmidt, 1974), and 15 species of freshwater aeolosomatids: A. aureum Marcus, 1944; A. beddardi Michaelsen, 1900; A. corderoi Du Bois-Reymond Marcus, 1944; A. evelinae Marcus, 1944; A. flavum Stolc, 1903; A. gertae Marcus, 1944; A. headleyi Beddard, 1888; A. hemprichi Ehrenberg, 1831; A. hyalinum Bunke, 1967; A. marcusi Van der Land, 1971; A. sawayai Marcus, 1944; A. travancorense Aiyer, 1926; A. variegatum Vejdovsky, 1884; and A. viride Stephenson, 1911, and Hystricosoma pictum Schmarda, 1861, species inquirenda. Eight of these are known only from South America.
... Annelid phylogeny is one of the largest unresolved problems within Metazoa Haeckel, 1874 (Almeida andChristoff ersen, 2001;Almeida et al., 2003;Jenner, 2004;Zrzavý et al., 2009). Th ere is now growing consensus that Polychaeta Sars, 1863 represents a paraphyletic group (McHugh, 1997;Westheide, 1997aWestheide, , 1997bRouse and Fauchald, 1998). ...
... Th e previous conclusions that Annelida Lamarck, 1803 andArticulata Cuvier, 1812 are also paraphyletic and should be replaced by a much more inclusive clade Metameria Christoff ersen and Araújo-de- Almeida, 1994 (Almeida andChristoff ersen, 2001;Almeida et al., 2003) have still not been accepted. Th e implications of these views are that not only Echiurida Baltzer, 1931 andPogonophora Ivanov, 1949 are descendants of annelid ancestors, but larger groups such as Ecdysozoa Aguinaldo et al., 1997 andDeuterostomata Huxley, 1874 are also descended from annelid-like marine ancestors. ...
... Th is phylogeny implies that Polychaeta, Annelida, and Articulata are paraphyletic groups, and contrasts with the recent consensus derived largely from molecular data that divides the Bilateria Metschnikoff , 1881 into 2 main clades, Lophotrochozoa Aguinaldo et al., 1997 andEcdysozoa (Philippe et al., 2009). Th is consensus assumes that Lophotrochozoa is also monophyletic, despite the evidence compiled by Almeida et al. (2003) against such an assumption, which in our opinion is not adequately supported by morphological data. Rouse and Fauchald (1997) fi rst proposed the monophyly of Polychaeta based on the presence of nuchal organs, but now admit that another possibility is that Clitellata have lost a number of morphological features that would help identify their sister group among the polychaetes (Rouse and Pleijel, 2003: 178;Rouse et al., 2008). ...
Molecular analyses have been unsuccessful in placing the clitellates among annelids. Available morphological characters are ordered into congruent transformation series according to Hennigian principles. Orbiniidae is chosen as the outgroup. I propose the following phylogeny [number of apomorphies within brackets]: (Clitellata sensu lato [6] (Questidae [6] + Apodadrilida, new [2] (Parergodrilidae [3] (Stygocapitella [3] + Parergodrilus [4]) + Oligochaeta [7] (Aphanoneura [2] (Aeolosomatidae [2] + Potamodrilidae [3]) + Dorsopharyngea, new [7] (Hrabeiellidae, new [6] + Euclitellata [5])))). Worms with ring-like clitella surrounding the body almost completely are herein renamed Euclitellata. Clitellata is expanded to include all annelids that, in addition to producing cocoons, have sperm receptacles and a restricted number of gonads. Oligochaeta is established as a valid clade for the hermaphroditic annelids bearing few or no chaetae. Questidae, Parergodrilidae, and Hrabeiella belong to Clitellata. Terrestrial "polychaetes", such as Parergodrilus and Hrabeiella, are actually clitellates. Hrabeiella is the sister group of Euclitellata, despite a secondary loss of spermathecae and clitellum. Aphanoneura belong to Oligochaeta.
... Formerly classified as a separate clade Questidae of uncertain affinities, the oligochaete-like appearance and reproductive biology prompted comparisons with clitellate oligochaetes (Giere and Riser 1981;Jamieson 1983;Giere et al. 2008). Consequently, a sister-group relationship of Questidae and Clitellata has been proposed by certain authors and even a taxon name, Apoclitellata, had been suggested (Almeida et al. 2003;Garraffoni and Amorim 2003). However, certain morphological characters raised serious doubts about such a relationship: for example, the structure of the spermatozoa and clitellum, structure of the chaetae, presence of nuchal organs and presence of lateral organs situated between the notopodial and neuropodial chaetae (Giere and Riser 1981;Rouse and Pleijel 2001;Giere et al. 2008). ...
The small taxon Questa comprises only meiofaunal species and shows oligochaete-like adaptations in its reproductive biology. Formerly, it was classified
as a separate polychaete group, Questidae, of uncertain affinities, but due to these oligochaete-like similarities, a relationship
with Clitellata was discussed. However, other morphological phylogenetic analyses questioned such a relationship, providing
evidence for common ancestry with Paraonidae and Orbiniidae. Molecular studies revealed that questids even form an in-group
of Orbiniidae, which refutes a clitellate relationship without doubt. On the other hand, morphological evidence supporting
this grouping is still considered weak. Among the external characters, the chaetation, comprising crenulated capillaries,
hooks and furcate chaetae, might strengthen this hypothesis. One of the internal characters stated to support this grouping
is the ventral pharynx, which as such, however, is widespread among polychaetes. This study is a first attempt to look for
specific structures in this organ, which might be regarded as synapomorphic of Questa and Orbiniidae. The ultrastructural analysis revealed a ventral buccal organ composed of large interstitial cells and transverse
muscle fibres and surrounded by an investing muscle system similar to that found in juvenile Orbiniidae. Thus, further morphological
evidence for the current position is provided. Moreover, since this structure is known as a larval or juvenile character in
Orbiniidae, this finding is also indicative for a progenetic origin of Questa, which might have occurred upon invading the interstitial environment.
KeywordsPharyngeal bulb–Musculature–Evolution–Progenesis–Polychaetes–Questidae
... Outgroup choice was established based on current phylogenetic hypotheses proposed among Capitellidae, Psammodrilidae, Arenicolidae and Maldanidae (Bartolomaeus, 1995(Bartolomaeus, , 1998Meyer & Bartolomaeus, 1996;Bartolomaeus & Meyer, 1999;Almeida et al., 2003;Rousset et al., 2007;. The taxon Maldanomorpha Meyer & Bartolomaeus, 1997, was proposed to group Arenicolidae + Maldanidae. ...
The Maldanidae annelid worms are reviewed and the phylogenetic relationships of their subgroups provided, based on Hennigian principles and maximum parsimony. Characters were coded as binary and multistate (transformation series). We used 33 terminal taxa (species), and 50 characters. Characters were treated as unordered and of equal weight, and analysis was run in TNT. Three equally most-parsimonious trees were obtained with heuristic searches, with lengths of 64 steps; CI = 0.95, and RI = 0.98. The monophyly of Maldanidae was supported with 100% of bootstrap and jackknife values. As a result of our analysis, Arenicolidae remains the sister-group of Maldanidae, and both should be referred to Maldanomorpha. Maldanidae was supported by the following synapomorphies: dorsal prostomium; prostomium keel-shaped and fused to peristomium; torus globose behind median chaetigers; median chaetigers greatly elongated; number of pre-anal segments reduced. The subfamily Bogueinae was not monophyletic; Boguea and Boguella were included within Rhodininae. Clymenura, previously included in the Clymenurinae, was included within Euclymeninae. The taxa Notoproctinae, Maldaninae, Nicomachinae and Euclymeninae were grouped in the Maldanoplaca, a new taxon. Eight further new clades have been found, but were not named.
... They proposed the Polychaeta to form two major clades, Scolecida and Palpata, the latter comprising the Canalipalpata (containing the remainder of the Sedentaria) and the Aciculata (containing the remainder of the Errantia). However, not all of these groups are strongly supported [10,11] and their monophyly has been questioned by morphological [12,13] as well as molecular studies [2,4,14]. As yet, a conclusive phylogeny for the segmented worms is still lacking and annelid systematics remain "one of the most vexing problems in invertebrate phylogenetics" [[3], page 1462]. ...
Paired mushroom bodies, an unpaired central complex, and bilaterally arranged clusters of olfactory glomeruli are among the most distinctive components of arthropod neuroarchitecture. Mushroom body neuropils, unpaired midline neuropils, and olfactory glomeruli also occur in the brains of some polychaete annelids, showing varying degrees of morphological similarity to their arthropod counterparts. Attempts to elucidate the evolutionary origin of these neuropils and to deduce an ancestral ground pattern of annelid cerebral complexity are impeded by the incomplete knowledge of annelid phylogeny and by a lack of comparative neuroanatomical data for this group. The present account aims to provide new morphological data for a broad range of annelid taxa in order to trace the occurrence and variability of higher brain centers in segmented worms.
Immunohistochemically stained preparations provide comparative neuroanatomical data for representatives from 22 annelid species. The most prominent neuropil structures to be encountered in the annelid brain are the paired mushroom bodies that occur in a number of polychaete taxa. Mushroom bodies can in some cases be demonstrated to be closely associated with clusters of spheroid neuropils reminiscent of arthropod olfactory glomeruli. Less distinctive subcompartments of the annelid brain are unpaired midline neuropils that bear a remote resemblance to similar components in the arthropod brain. The occurrence of higher brain centers such as mushroom bodies, olfactory glomeruli, and unpaired midline neuropils seems to be restricted to errant polychaetes.
The implications of an assumed homology between annelid and arthropod mushroom bodies are discussed in light of the 'new animal phylogeny'. It is concluded that the apparent homology of mushroom bodies in distantly related groups has to be interpreted as a plesiomorphy, pointing towards a considerably complex neuroarchitecture inherited from the last common ancestor, Urbilateria. Within the annelid radiation, the lack of mushroom bodies in certain groups is explained by widespread secondary reductions owing to selective pressures unfavorable for the differentiation of elaborate brains. Evolutionary pathways of mushroom body neuropils in errant polychaetes remain enigmatic.
... The genital organs are limited to a few segments and female questids bear a glandular epidermis that forms a cocoon (Giere and Riser, 1981;Giere and Erséus, 1998). The latter structure has been interpreted as homologous to the clitellum by some authors (Almeida et al., 2003;Garraffoni and Amorim, 2003), and subsequent cladistic analyses have suggested a sistergroup relationship between questids and clitellates, a taxon which was named ''Apoclitellata" (Almeida et al., 2003). However, other authors have contradicted a homologization of the clitellate clitellum with the glandular epidermis region in female questids based on profound structural differences (Giere and Erséus, 1998;Giere et al., 2008). ...
... The genital organs are limited to a few segments and female questids bear a glandular epidermis that forms a cocoon (Giere and Riser, 1981;Giere and Erséus, 1998). The latter structure has been interpreted as homologous to the clitellum by some authors (Almeida et al., 2003;Garraffoni and Amorim, 2003), and subsequent cladistic analyses have suggested a sistergroup relationship between questids and clitellates, a taxon which was named ''Apoclitellata" (Almeida et al., 2003). However, other authors have contradicted a homologization of the clitellate clitellum with the glandular epidermis region in female questids based on profound structural differences (Giere and Erséus, 1998;Giere et al., 2008). ...
... This clade is supported by analyses of the concatenated six-gene dataset, of the gene order dataset, and by occurrence of an 18 bp indel within the nad1 alignment. These results support earlier molecular analyses which were based mainly on the ribosomal 18S (e.g., Erséus et al., 2000;Bleidorn et al., 2003a,b;Rousset et al., 2007) and rejects the idea of a taxon ''Apoclitellata" as proposed by Almeida et al. (2003) and Garraffoni and Amorim (2003). As such, our results are congruent with the notion of Giere and Erséus (1998) and Giere et al. (2008) that the clitellum-like structures found in females of Questa species cannot be homologized with the clitellum of the Clitellata, and in contrast, should be regarded as a unique structure of questids. ...
Orbiniid phylogeny is matter of debate and incongruence between hypothesis based on molecules and morphology has been repeatedly reported. Moreover, the phylogenetic position of the “oligochaetoid polychaetes” of the taxon Questa varies between morphological and molecular cladistic analyses. Here, we present a nearly complete mitochondrial genome of Questa ersei. The mitochondrial gene order is roughly identical to known orbiniid taxa. Several translocations of tRNAs are unique to Orbiniidae and Questa when compared to other annelid mitochondrial genomes. Additionally, we assembled sequence data of six genes (18S, 16S, cox1, cox3, nad1, nad4) for a representative orbiniid taxon sampling and analysed all data in concatenation using Maximum Likelihood and Bayesian inference. For comparison with morphology we compiled a morphological data matrix for all taxa included in our molecular analyses. Our results strongly support a close relationship of Questa with orbiniids (sequence data, gene order, an 18 bp indel, morphology), and a position nested within orbiniids is recovered in our sequence based analyses. We demonstrate remarkable incongruence of most included morphological characters with the recovered best ML tree and suppose that repeated independent character loss might be an explanation.
