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An approach towards a systematic revision of Marionina Michaelsen, 1890 is made through an historical overview of its nomenclature and definition, and a thorough characterization of its type species, the South Georgian marine littoral Pachydrilus georgianus Michaelsen, 1888. Relevant sections of early enchytraeid literature provide the background for appreciating the complex taxonomic history of the genus and giving a final word as to the controversial validity of its name, authority and date. Marionina in its current acceptation comprises about 100 nominal species, but the paper documents how, since its establishment, the genus has been an artificial assemblage of unrelated taxa, whose taxonomy cannot be sorted out (1) without finding new morphological characters and improving the standard of descriptions, and (2) without using a total evidence approach (morphology and molecules) within a phylogenetic framework. Confusion about the identity of the type species, originally briefly described and only partially figured, is unravelled upon examination of the syntypes available in Hamburg and Berlin. Since neither series proved to be monospecific, a lectotype is designated to assure correct and consistent application of the name in the future. [ABSTRACT FROM AUTHOR]

The life cycle of the histozoic myxozoan parasiteHenneguya nuessliniwas investigated in two salmonid host species. Naïve brown trout,Salmo trutta, and brook trout,Salvelinus fontinalis, were experimentally infected in two trials by triactinomyxon type actinospores from naturally infectedTubifex tubifex. In exposed common carp,Cyprinus carpio, no myxospore production was detected. The parasite formed cysts with mature myxospores in the connective tissue of the fish 102 days post-exposure. The morphology of both actinosporean and myxosporean stages was described by light microscopy and a 1417-bp fragment of the 18S rDNA gene was sequenced. Sequence analysis confirmed the absolute congruence of the two developmental stages and assisted in determining species identity. Host range, tissue specificity and myxospore measurements provided sufficiently distinctive features to confirm species validity and were thus crucial for identification. The triactinomyxon spores had 16 secondary germ cells, unique dimensions, a very opaque sporoplasm matrix and three conspicuously protruding, pyriform polar capsules. This is the first record of aHenneguyasp. life cycle with a triactinomyxon-type actinospore, which suggests a close relationship with theMyxobolusgroup and a polyphyletic origin of the genusHenneguya. [ABSTRACT FROM AUTHOR]

The marine littoral earthworm Pontodrilus litoralis (Grube, 1855) is widely distributed and is reported as a single species. This study utilized an integrative taxonomic approach based upon morphological examination, phylogenetic reconstruction, and molecular species delimitation, to test whether the taxon is a single species or a species complex. For this, a total of 114 P. litoralis specimens collected from North America, Africa, Australia and Oceania, Europe and Asia were used. The phylogenetic analyses revealed deeply divergent mitochondrial lineages and a high level of genetic diversity among P. litoralis populations. Both single and multi-locus species delimitation analyses yielded several molecular operational taxonomic units. Therefore, due to the homogeneity of morphological characteristics, it is likely that the morphospecies P. litoralis is a complex of four or more cryptic species, suggesting that more sampling is required and that the population structure genetic data and gene flow need to be investigated., (© 2024. The Author(s).)

Freshwater annelids are globally widespread in aquatic ecosystems, but their diversity is severely underestimated. Obvious morphological features to define taxa are sparse, and molecular phylogenetic analyses regularly discover cryptic diversity within taxa. Despite considerable phylogenetic work on certain clades, many groups of freshwater annelids remain poorly understood. Included among these are water nymph worms of the genus Chaetogaster (Clitellata: Tubificida: Naididae: Naidinae). These worms have diverged from the detritivorous diet of most oligochaetes to become more predatory and exist as omnivores, generalist predators, parasites, or symbionts on other invertebrates. Despite their unusual trophic ecology, the true diversity of Chaetogaster and the phylogenetic relationships within the genus are uncertain. Only three species are commonly referenced in the literature (Chaetogaster diaphanus, Chaetogaster limnaei, and Chaetogaster diastrophus), but additional species have been described and prior molecular data suggests that there is cryptic diversity within named species. To clarify the phylogenetic diversity of Chaetogaster, we generated the first molecular phylogeny of the genus using mitochondrial and nuclear sequence data from 128 worms collected primarily across North America and Europe. Our phylogenetic analyses suggest that the three commonly referenced species are a complex of 24 mostly cryptic species. In our dataset, Chaetogaster "diaphanus" is represented by two species, C. "limnaei" is represented by three species, and C. "diastrophus" is represented by 19 species. North American and European sequences are largely interspersed across the phylogeny, with four pairs of clades involving distinct North American and European sister groupings. Overall, our study demonstrates that the species diversity of Chaetogaster has been underestimated and that carnivory has evolved at least twice in the genus. Chaetogaster is being used as a model for symbiotic evolution and the loss of regenerative ability, and our study indicates that researchers must be careful to identify which species of Chaetogaster they are working with in future studies., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)

A new Qinghai-Tibet Plateau species, Rhyacodrilus tanggulaensis Jiang & Cui sp. nov. (Annelida, Clitellata, Naididae, Rhyacodrilinae), is described, and its phylogenetic relationships within the genus is assessed on the basis of both mitochondrial (16S rDNA, COⅠ gene) and nuclear (ITS2) markers. Data from 32 species of Naididae, representing 7 subfamilies and 25 genera are used. Ten species were chosen as outgroup taxa. The molecular data were analyzed by Bayesian inference. The new species is distinguished from other species of Rhyacodrilus by the following combination of characters: dorsal and ventral chaetae with distal tooth 2-3 times longer than proximal, spermathecal and penial chaetae present, atria long and tubular, atrial duct conspicuous. The analyses of the combined molecular data corroborate the close relationship between Naidinae and the rhyacodriline genera Rhyacodrilus, Monopylephorus, and Ainudrilus, and show that the new species is more closely related to R. falciformis, R pigueti, R. okamikae and R. subterraneus, than to R. sinicus, another Chinese species, R. hiemalis and R. coccineus.

Background: Deep mitochondrial divergences were observed in Scandinavian populations of the terrestrial to semi-aquatic annelid Fridericia magna (Clitellata: Enchytraeidae). This raised the need for testing whether the taxon is a single species or a complex of cryptic species., Results: A total of 62 specimens from 38 localities were included in the study, 44 of which were used for species delimitation. First, the 44 specimens were divided into clusters using ABGD (Automatic Barcode Gap Discovery) on two datasets, consisting of sequences of the mitochondrial markers COI and 16S. For each dataset, the worms were divided into six not completely congruent clusters. When they were combined, a maximum of seven clusters, or species hypotheses, were obtained, and the seven clusters were used as input in downstream analyses. We tested these hypotheses by constructing haplowebs for two nuclear markers, H3 and ITS, and in both haplowebs the specimens appeared as a single species. Multi-locus species delimitation analyses performed with the Bayesian BPP program also mainly supported a single species. Furthermore, no apparent morphological differences were found between the clusters. Two of the clusters were partially separated from each other and the other clusters, but not strongly enough to consider them as separate species. All 62 specimens were used to visualise the Scandinavian distribution, of the species, and to compare with published COI data from other Fridericia species., Conclusion: We show that the morphospecies Fridericia magna is a single species, harbouring several distinct mitochondrial clusters. There is partial genetic separation between some of them, which may be interpreted as incipient speciation. The study shows the importance of rigorous species delimitation using several independent markers when deep mitochondrial divergences might give the false impression of cryptic speciation.

The description of Helobdella stagnalis (Linnaeus, 1758) has emphasized the presence of a nuchal, chitinous scute located on the dorsal surface in the first third of the body as the diagnostic character for the species. Historically, identifications of species of Helobdella have relied heavily on this character and, as a result, Helobdella stagnalis has been reported from an inordinately broad geographic range, including Europe, Asia, Africa, North America, and South America. In addition to a few earlier investigations, a recent analysis showed that great genetic distances (orders of magnitude greater than previous estimations of intraspecific divergence in leeches) are present between scute-bearing specimens identified as H. stagnalis from Europe and North America, implying that H. stagnalis does not occur in North America. The present study expands the geographic boundaries of taxon sampling for both European and North American taxa, and re-examines the phylogenetic relationships and cytochrome c oxidase subunit I (COI) variation within scute-bearing species of the genus Helobdella. Our analyses include specimens putatively identified as "Helobdella stagnalis" from Sweden, Norway, Iceland, England, France, Italy, Slovenia, Turkey, Russia, and Iran, as well as numerous localities covering Canada and the USA. Our results corroborate previous studies in that European and west Asian specimens form a clade, including the neotype, which is separate from North American taxa. To alleviate future taxonomic confusion, we redescribe H. stagnalis and designate a neotype from the inferred type locality. The designation of a neotype stabilizes the taxonomy of scute-bearing leeches of the genus Helobdella and enables us to definitively correct erroneous identifications reported in previous studies. We also note that at least four lineages of scute-bearing, North American species of Helobdella lack formal descriptions.

Leeches (Hirudinida) comprise a charismatic, yet often maligned group of organisms. Despite their ecological, economic, and medical importance, a general consensus on the phylogenetic relationships of major hirudinidan lineages is lacking. This absence of a consistent, robust phylogeny of early-diverging lineages has hindered our understanding of the underlying processes that enabled evolutionary diversification of this clade. Here, we used an anchored hybrid enrichment-based phylogenomic approach, capturing hundreds of loci to investigate phylogenetic relationships among major hirudinidan lineages and their closest living relatives. Our results suggest that a dramatic reinterpretation of early leech evolution is warranted. We recovered Branchiobdellida as sister to a clade that includes all major lineages of hirudinidans, but found Acanthobdella to be nested within Oceanobdelliformes. These results cast doubt on the utility of Acanthobdella as a "missing link" used to explain the origin of blood-feeding in hirudineans. Further, our results support a deep divergence between predominantly marine and freshwater lineages, while not supporting the reciprocal monophyly of jawed and proboscis-bearing leeches. To sum up, our phylogenomic resolution of early-diverging leeches provides a necessary foundation for illuminating the evolution of host-symbiont associations and key adaptations that have allowed leeches to colonize a wide diversity of habitats worldwide., (© The Author(s) 2019. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.)

Major habitat transitions, such as those from marine to freshwater habitats or from aquatic to terrestrial habitats, have occurred infrequently in animal evolution and may represent a barrier to diversification. Identifying genomic events associated with these transitions can help us better understand mechanisms that allow animals to cross these barriers and diversify in new habitats. Study of the Capitella telata and Helobdella robusta genomes allows examination of one such habitat transition (marine to freshwater) in Annelida. Initial examination of these genomes indicated that the freshwater leech H. robusta contains many more copies (12) of the sodium-potassium pump alpha-subunit (Na + /K + -ATPase) gene than does the marine polychaete C. telata (2). The sodium-potassium pump plays a key role in maintenance of cellular ionic balance and osmoregulation, and Na + /K + -ATPase duplications may have helped annelids invade and diversify in freshwater habitats. To assess whether the timing of Na + /K + -ATPase duplications coincided with the marine-to-freshwater transition in Clitellata, we used transcriptomic data from 18 annelid taxa, along with the two genomes, to infer a species phylogeny and identified Na + /K + -ATPase gene transcripts in order to infer the timing of gene duplication events using tree-based methods. The inferred timing of Na + /K + -ATPase duplication events is consistent with the timing of the initial marine-to-freshwater transition early in the history of clitellate annelids, supporting the hypothesis that gene duplications may have played a role in the annelid diversification into freshwater habitats., (© 2019 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2019 European Society For Evolutionary Biology.)

Chamaedrilus (earlier referred to as Cognettia) is a well-known genus of terrestrial and limnic enchytraeids, currently with 19 known species in the world. Some of its species are morphologically cryptic and can only be identified using genetic (DNA) information. Many of them reproduce asexually, and the prevalence of sexual mature individuals is generally low in the populations. Chamaedrilus asloae sp. nov. (Clitellata: Enchytraeidae) is described based on material from two rivers in Norway, one in Sweden, and from a wet deciduous forest in Denmark. With the material at hand, no morphological characters completely separate C. asloae from C. chalupskyi; none of the available specimens of the new species are sexually mature. However, four molecular markers (two mitochondrial, two nuclear) support that C. asloae is a distinct, separately evolved lineage, which is sister to a clade consisting of C. glandulosus and C. varisetosus. In this study, too, the fully developed sexual organs of C. chalupskyi and C. varisetosus are described and illustrated.

The small synanthropic and peregrine earthworm Microscolex phosphoreus (Dugès, 1837) is reported for the first time from Siberia. Morphological and DNA barcode (COI) analyses of this and widely separate samples worldwide demonstrate that, as currently identified, M. phosphoreus is a heterogeneous taxon, with divergent lineages occurring often in the same locality and hardly providing geographically structured genetic signals. The combined morphological and genetic evidence suggests that at least four of the found clades should be reclassified as separate species, both morphologically and genetically distinct from each other. However, as the specimen number was limited and only the COI gene was studied for the genetic work, we hesitate in formally describing new species. There would also be the problem of assigning the available names to specific lineages. Our findings encourage careful external and anatomical examination and using reliable characters such as the interchaetal distances and spermathecal morphology for correct identification and for deeper evaluation of cryptic diversity in this interesting bioluminescent worm.

Two new species of Tubificoides (subfamily Tubificinae), T. charlotteae n. sp. and T. mackiei n. sp., are described based on morphological analyses. Both species were flagged as potentially cryptic in a previous investigation, based on both mitochondrial and nuclear sequence data. Tubificoides charlotteae n. sp., known only from an intertidal site in southern Spain, is characterized by the lack of cuticular papillation, the possession of several needle-like hair chaetae in dorsal bundles, a cone-shaped penis sheath, and a rather large, muscular penial sac. It strongly resembles the north-west European, largely sublittoral species T. amplivasatus, but differs from this species in terms of body size, width of vas deferens, and the shape and size of both the ejaculatory duct and penial sac. Tubificoides mackiei n. sp., collected from the southeast coast of Norway and the west coast of Sweden, is characterized by the lack of cuticular papillae and hair chaetae, and the possession of a rather long penis sheath with a wide terminal opening. It shares several morphological features with the sympatric species Tubificoides pseudogaster, but is distinguished from the latter by the detailed morphology and length of the penis sheaths, the width of the atrium, and the lower maximal number of bifid chaetae in dorsal preclitellar bundles. The utility of an integrative comparative approach, combining molecules and morphology, for the identification and delineation of new taxa within Tubificoides is briefly discussed.

Nuclear molecular evidence, for example, the rapidly evolving Internal Transcribed Spacer region (ITS), integrated with maternally inherited (mitochondrial) COI barcodes, has provided new insights into the diversity of clitellate annelids. PCR amplification and sequencing of ITS, however, are often hampered by poor specificity of primers used. Therefore, new clitellate-specific primers for amplifying the whole ITS region (ITS: 29F/1084R) and a part of it (ITS2: 606F/1082R) were developed on the basis of a collection of previously published ITS sequences with flanking rDNA coding regions. The specificity of these and other ITS primers used for clitellates were then tested in silico by evaluating their mismatches with all assembled and annotated sequences (STD, version r127) from EMBL, and the new primers were also tested in vitro for a taxonomically broad sample of clitellate species (71 specimens representing 11 families). The in silico analyses showed that the newly designed primers have a better performance than the universal ones when amplifying clitellate ITS sequences. In vitro PCR and sequencing using the new primers were successful, in particular, for the 606F/1082R pair, which worked well for 65 of the 71 specimens. Thus, using this pair for amplifying the ITS2 will facilitate further molecular systematic investigation of various clitellates. The other pair (29F/1084R), will be a useful complement to existing ITS primers, when amplifying ITS as a whole.

The phylogenetic relationships within Naidinae (Annelida, Clitellata, Naididae) were investigated, using six molecular markers, both mitochondrial (12S rDNA, 16S rDNA, the COI gene) and nuclear (18S rDNA, 28S rDNA, the ITS region). Thirty-seven nominal species, representing 16 of the 22 genera recognized in the subfamily, were included, and the Nais communis/variabilis species complex was represented by six different morphotypes. Ten other species of Naididae were selected as outgroups. The data were analysed by Bayesian inference and Maximum Likelihood. The phylogeny corroborates monophyly of the Naidinae, and the separate status of the genus Pristina (Pristininae) and the Opistocystinae. Relationships within Naidinae are largely well supported, but in some parts unexpected: (1) A clade containing the largely tropical genera Dero and Branchiodrilus is sister to the rest of the subfamily, and together with a third tropical genus, Allonais, they form a basal paraphyly. All these genera show morphological adaptations to environmental hypoxia, leading to the conclusion that Naidinae originated in tropical freshwaters. (2) The genera Dero, Nais and Piguetiella are paraphyletic. (3) At least Branchiodrilus, Paranais, Chaetogaster, Nais, Stylaria appear to contain cryptic species. Morphological characters, especially those associated with chaetae, are to a great extent homoplastic within Naidinae, which certainly has contributed to the overall taxonomic confusion of this subfamily., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Lumbricillus is a genus of clitellate worms with about 80 described species that inhabit marine and limnic habitats. This study follows a recent analysis of the phylogeny of the genus based on 24 species of Lumbricillus collected mainly in Norway and Sweden. We provide the illustrated taxonomic descriptions of all these species and describe two of them as new; Lumbricillus latithecatus sp. n. and L. scandicus sp. n. Using the recent phylogeny, we informally divide Lumbricillus into five distinct morphological groups, into which we also tentatively place the Lumbricillus species not included in this study. Furthermore, we establish Claparedrilus gen. n. , with the type species C. semifuscoides sp. n. , and transfer Pachydrilus semifuscus Claparède, 1861 (previously referred to Lumbricillus ) into said genus.

Limnodrilus species are annelid worms distributed worldwide in various freshwater sediments. The systematics of Limnodrilus has chiefly been based on morphology, but the genus has not been subject to any closer phylogenetic studies over the past two decades. To reconstruct the evolutionary history of Limnodrilus, and to assess the monophyly of this genus and its systematic position within the subfamily Tubificinae (Annelida: Clitellata: Naididae), 45 Limnodrilus specimens, representing 19 species, and 35 other naidid species (representing 24 genera) were sampled. The data consisted of sequences of three mitochondrial genes (COI, 12S and 16S rDNA) and four nuclear markers (18S and 28S rDNA, Histone 3, and ITS). The phylogeny was estimated, using Maximum Likelihood and Bayesian analyses of concatenated data of seven DNA loci, as well as a multi-locus coalescent-based approach. All analyses strongly suggest that Limnodrilus is monophyletic, but only if the morphospecies L. rubripenis is removed from it. Limnodrilus rubripenis and (at least) Baltidrilus, Lophochaeta and some species attributed to Varichaetadrilus comprise the sister group to the clade Limnodrilus sensu stricto, and the latter is further divided into three well-supported groups. One of them contains morphospecies characterized by short cuticular penis sheaths and enlarged chaetae in anterior segments (L. udekemianus, L. silvani and L. grandisetosus). The second is a small group of species with moderately long penis sheaths, i.e., L. sulphurensis and L. profundicola. The third, and largest group, includes not only the multitude of cryptic species in the L. hoffmeisteri complex, but also other, morphologically distinct, species nested within this complex. All studied species in this large group have long penis sheaths, which are exceptionally long in L. claparedianus, L. maumeensis, and a form morphologically intermediate between L. claparedianus and L. cervix. The identification and classification of these groups provide a framework for directed sampling in further phylogenetic studies, and for revisionary work on the L. hoffmeisteri complex and other unresolved Limnodrilus species., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Background: Earthworms (Crassiclitellata) are a diverse group of annelids of substantial ecological and economic importance. Earthworms are primarily terrestrial infaunal animals, and as such are probably rather poor natural dispersers. Therefore, the near global distribution of earthworms reflects an old and likely complex evolutionary history. Despite a long-standing interest in Crassiclitellata, relationships among and within major clades remain unresolved., Methods: In this study, we evaluate crassiclitellate phylogenetic relationships using 38 new transcriptomes in combination with publicly available transcriptome data. Our data include representatives of nearly all extant earthworm families and a representative of Moniligastridae, another terrestrial annelid group thought to be closely related to Crassiclitellata. We use a series of differentially filtered data matrices and analyses to examine the effects of data partitioning, missing data, compositional and branch-length heterogeneity, and outgroup inclusion., Results and Discussion: We recover a consistent, strongly supported ingroup topology irrespective of differences in methodology. The topology supports two major earthworm clades, each of which consists of a Northern Hemisphere subclade and a Southern Hemisphere subclade. Divergence time analysis results are concordant with the hypothesis that these north-south splits are the result of the breakup of the supercontinent Pangaea., Conclusions: These results support several recently proposed revisions to the classical understanding of earthworm phylogeny, reveal two major clades that seem to reflect Pangaean distributions, and raise new questions about earthworm evolutionary relationships.

DNA-barcoding, using the mitochondrial marker COI, has been found successful for the identification of specimens in many animal groups, but may not be suited for species discovery and delimitation if used alone. In this study, we investigate whether two observed COI haplogroups in the earthworm Aporrectodea longa correspond to two cryptic species or if the variation is intraspecific. This is done by complementing COI with two nuclear markers, ITS2 and Histone 3. The variation is studied using distance methods, parsimony networks and Bayesian coalescent trees, and the statistical distinctness of the groups is tested on gene trees using the genealogical sorting index, Rosenberg's P AB and Rodrigo et al.'s P (RD) . We also applied multilocus species delimitation based on the multispecies coalescence model. The two haplogroups were found in COI, and all tests except P (RD) found them to be significantly distinct. However, in ITS2, the same groups were not recovered in any analyses or tests. H3 was invariable in A. longa, and was, therefore, included only in the multilocus analysis, which preferred a model treating A. longa as one species over a model splitting it into two. We also compared two measurements of size, body length, and no. of segments between the groups. No difference in body length was found, and although a significant difference in no. of segments was noted the haplogroup with the lower mean showed both the highest and the lowest value. When combined, these results led us to the conclusion that there is no support for the separation of A. longa into two cryptic species. This study again highlights the importance of complementing mitochondrial barcodes with more data when establishing species boundaries.

Cryptic mitochondrial (mt) lineages are known to exist in the earthworm morphospecies Lumbricus rubellus and L. terrestris. The latter was recently split into two species, L. terrestris and L. herculeus, based on large genetic distances and a statistical difference in body size. There is support for the separation of some lineages in L. rubellus into species, whereas other lineages, separated by similar mt genetic distances, have been found to be part of the same species. However, no study has evaluated the status of the cryptic mt lineages in L. terrestris-L. herculeus and L. rubellus using nuclear genes. We use a combination of methods to reveal extensive cryptic speciation and limited hybridization in Lumbricus, based on one nuclear (H3) and one mitochondrial (COI) marker. Using a Bayesian multi-locus species delimitation method, as well as single gene haplotype networks and gene trees, we delimit seven well supported cryptic species within the morphospecies L. rubellus, and confirm the split within the species-pair L. terrestris-L. herculeus. Limited hybridization was found between the most common species of L. rubellus (A) in northern Europe and two other species (B and H) in this complex, as well as between L. terrestris and L. herculeus. Deep mt divergence was found within L. terrestris s.str. but no support for further splitting of this taxon was found. Both L. rubellus and L. terrestris are well studied model organisms, and considering that cryptic species and hybridization were found within them, it is important that they are properly identified in future studies., (Copyright © 2016 Elsevier Inc. All rights reserved.)

The level of integration between associated partners can range from ectosymbioses to extracellular and intracellular endosymbioses, and this range has been assumed to reflect a continuum from less intimate to evolutionarily highly stable associations. In this study, we examined the specificity and evolutionary history of marine symbioses in a group of closely related sulphur-oxidizing bacteria, called Candidatus Thiosymbion, that have established ecto- and endosymbioses with two distantly related animal phyla, Nematoda and Annelida. Intriguingly, in the ectosymbiotic associations of stilbonematine nematodes, we observed a high degree of congruence between symbiont and host phylogenies, based on their ribosomal RNA (rRNA) genes. In contrast, for the endosymbioses of gutless phallodriline annelids (oligochaetes), we found only a weak congruence between symbiont and host phylogenies, based on analyses of symbiont 16S rRNA genes and six host genetic markers. The much higher degree of congruence between nematodes and their ectosymbionts compared to those of annelids and their endosymbionts was confirmed by cophylogenetic analyses. These revealed 15 significant codivergence events between stilbonematine nematodes and their ectosymbionts, but only one event between gutless phallodrilines and their endosymbionts. Phylogenetic analyses of 16S rRNA gene sequences from 50 Cand. Thiosymbion species revealed seven well-supported clades that contained both stilbonematine ectosymbionts and phallodriline endosymbionts. This closely coupled evolutionary history of marine ecto- and endosymbionts suggests that switches between symbiotic lifestyles and between the two host phyla occurred multiple times during the evolution of the Cand. Thiosymbion clade, and highlights the remarkable flexibility of these symbiotic bacteria., (© 2016 The Authors. Molecular Ecology published by John Wiley & Sons Ltd.)

A new species of the tubificine genus Limnodrilus is described and COI barcoded from Sulphur Cave and associated springs in Colorado, USA. The habitats are characterized by high sulfide concentrations. The new species, L. sulphurensis, is distinguished from all congeners by the elongate, nearly parallel teeth of chaetae in its anterior segments. It has a penis sheath resembling that of L. profundicola; consequently, museum specimens and new collections are examined here to resolve some of the taxonomic confusion surrounding that widespread, but uncommon species.

The taxonomy of Chamaedrilusglandulosus (Michaelsen, 1888) s. l., most commonly known previously as Cognettiaglandulosa, is revised. A recent molecular systematic study has shown that this taxon harbours two cryptic, but genetically well separated lineages, each warranting species status. In this study these two lineages are scrutinized morphologically, on the basis of Michaelsen's type material as well as newly collected specimens from Central and Northern Europe. Chamaedrilusglandulosus s. s. is redescribed and Chamaedrilusvarisetosus sp. n. is recognized as new to science. The two species are morphologically very similar, differing mainly in size, but seem to prefer different habitats, with Chamaedrilusglandulosus being a larger aquatic species, and Chamaedrilusvarisetosus being smaller and mainly found in moist to wet soil.

Lake Hazar is an alkaline oligotrophic lake of tectonic origin, located in the Eastern Anatolia region in Turkey, 1248 a a.s.l. Its surface area is 80 km2, the average depth 93 m and maximum depth 205 m. The lake and its surroundings an under protection as a region of historical value. During the present study (2007-2012), samples were taken from 15 stations located at a depth of 2-200 m. Oligochaeta comprised 69% of the total invertebrate abundance. The profundal olgochaete fauna was found to consist of only three tubificid taxa, all of the subfamily Tubificinae. Potamothrix alatus hazaricus Timm & Arslan, n. ssp. was dominating anywhere down to maximum depths while Psammoryctides barbatus (Grube) and Ilyodrilus(?) sp. occurred seldom. All three are new records for Lake Hazar. Potamothrix alatus hazaricus shares the "winged" body shape in its genital region with the nominal, brackish-water subspecies P. a. alatus Finogenova, 1972, and the lateral position of the spermathecal pores and the shape of the ventral chaetae with the freshwater subspecies P. a. paravanicus Poddubnaja & Pataridze, 1989 known from Transcaucasian lakes. The mitochondrial COI barcoding gene suggests long separation between the two taxa, but the nuclear ITS region shows no variation. The generic position of Ilyodrilus (?) sp. remains obscure since its internal genitalia could not be studied.

Background: The question of how many marine species exist is important because it provides a metric for how much we do and do not know about life in the oceans. We have compiled the first register of the marine species of the world and used this baseline to estimate how many more species, partitioned among all major eukaryotic groups, may be discovered., Results: There are ∼226,000 eukaryotic marine species described. More species were described in the past decade (∼20,000) than in any previous one. The number of authors describing new species has been increasing at a faster rate than the number of new species described in the past six decades. We report that there are ∼170,000 synonyms, that 58,000-72,000 species are collected but not yet described, and that 482,000-741,000 more species have yet to be sampled. Molecular methods may add tens of thousands of cryptic species. Thus, there may be 0.7-1.0 million marine species. Past rates of description of new species indicate there may be 0.5 ± 0.2 million marine species. On average 37% (median 31%) of species in over 100 recent field studies around the world might be new to science., Conclusions: Currently, between one-third and two-thirds of marine species may be undescribed, and previous estimates of there being well over one million marine species appear highly unlikely. More species than ever before are being described annually by an increasing number of authors. If the current trend continues, most species will be discovered this century., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Metabarcoding approaches use total and typically degraded DNA from environmental samples to analyse biotic assemblages and can potentially be carried out for any kinds of organisms in an ecosystem. These analyses rely on specific markers, here called metabarcodes, which should be optimized for taxonomic resolution, minimal bias in amplification of the target organism group and short sequence length. Using bioinformatic tools, we developed metabarcodes for several groups of organisms: fungi, bryophytes, enchytraeids, beetles and birds. The ability of these metabarcodes to amplify the target groups was systematically evaluated by (i) in silico PCRs using all standard sequences in the EMBL public database as templates, (ii) in vitro PCRs of DNA extracts from surface soil samples from a site in Varanger, northern Norway and (iii) in vitro PCRs of DNA extracts from permanently frozen sediment samples of late-Pleistocene age (~16,000-50,000 years bp) from two Siberian sites, Duvanny Yar and Main River. Comparison of the results from the in silico PCR with those obtained in vitro showed that the in silico approach offered a reliable estimate of the suitability of a marker. All target groups were detected in the environmental DNA, but we found large variation in the level of detection among the groups and between modern and ancient samples. Success rates for the Pleistocene samples were highest for fungal DNA, whereas bryophyte, beetle and bird sequences could also be retrieved, but to a much lesser degree. The metabarcoding approach has considerable potential for biodiversity screening of modern samples and also as a palaeoecological tool., (© 2012 Blackwell Publishing Ltd.)

The widely studied and invasive earthworm, Lumbricus terrestris L., 1758 has been the subject of nomenclatural debate for many years. However these disputes were not based on suspicions of heterogeneity, but rather on the descriptions and nomenclatural acts associated with the species name. Large numbers of DNA barcode sequences of the cytochrome oxidase I obtained for nominal L. terrestris and six congeneric species reveal that there are two distinct lineages within nominal L. terrestris. One of those lineages contains the Swedish population from which the name-bearing specimen of L. terrestris was obtained. The other contains the population from which the syntype series of Enterion herculeum Savigny, 1826 was collected. In both cases modern and old representatives yielded barcode sequences allowing us to clearly establish that these are two distinct species, as different from one another as any other pair of congeners in our data set. The two are morphologically indistinguishable, except by overlapping size-related characters. We have designated a new neotype for L. terrestris. The newly designated neotype and a syntype of L. herculeus yielded DNA adequate for sequencing part of the cytochrome oxidase I gene (COI). The sequence data make possible the objective determination of the identities of earthworms morphologically identical to L. terrestris and L. herculeus, regardless of body size and segment number. Past work on nominal L. terrestris could have been on either or both species, although L. herculeus has yet to be found outside of Europe.

Species identifications based on DNA barcoding rely on the correct identity of previously barcoded specimens, but little attention has been given to whether deposited barcodes include correspondence to the species' name-bearing type. The information content associated with COX1 sequences in the two most commonly used repositories of barcodes, GenBank and the Barcode of Life Data System (BOLD), is often insufficient for subsequent evaluation of the robustness of the identification procedure. We argue that DNA barcoding and taxonomy alike will benefit from more information content in the annotations of barcoded specimens as this will allow for validation and re-evaluation of the initial specimen identification. The aim should be to closely connect specimens from which reference barcodes are generated with the holotype through straight-forward taxonomy, and geographical and genetic correlations. Annotated information should also include voucher specimens and collector/identifier information. We examine two case studies based on empirical data, in which barcoding and taxonomy benefit from increased information content. On the basis of data from the first case study, we designate a barcoded neotype of the European medicinal leech, Hirudo medicinalis, on morphological and geographical grounds.

Prior attempts to resolve the phylogenetic relationships of the cosmopolitan, marine clitellate genus Tubificoides, using only morphology, resulted in unresolved trees. In this study, three mitochondrial and three nuclear loci (5912 aligned sites) were analyzed, representing 14 morphologically separate species. Genetic distances within and between these forms on the basis of the mitochondrial genes (COI, 16S and 12S) revealed that 18 distinct mitochondrial lineages were represented in the data set. After analyzing also nuclear data (28S, 18S and ITS) we conclude that 17 separately evolving lineages (i.e., phylogenetic species) were represented, including three new, cryptic species closely related to T. pseudogaster, T. amplivasatus and T. insularis, respectively. Special emphasis was put on the DNA barcoding gene (COI), which was subject to haplotype diversity analysis and, for four species, diagnostic position (as determined by the Characteristic Attribute Organization System [CAOS]) screening. Typically, the intralineage variation was 1-2 orders of magnitude smaller than the interlineage divergence, making COI useful for identification of species within Tubificoides. The genetic data corroborate that many of the morphospecies are coherent but widely distributed metapopulations. Monophyly of the genus is supported and the evolutionary history of parts of the genus is revealed by phylogenetic analysis of the combined data set. A northern hemisphere origin of the genus is suggested, and most of the widely distributed species are members of one particular clade. Two morphological characters previously emphasized in Tubificoides taxonomy (hair chaetae and cuticular papillation) were optimized on the phylogenetic tree, revealing considerable homoplasy, belying the utility of these features as phylogenetic markers., (Copyright © 2010 Elsevier Inc. All rights reserved.)

A multigene data set (12S, 16S, and COI mitochondrial DNA; 18S and 28S nuclear DNA) was analyzed by Bayesian inference to estimate the phylogeny of a sample of the clitellate family Enchytraeidae (86 species representing 14 nominal genera). Monophyly, as well as a basal dichotomy, of the family Enchytraeidae obtained maximum support, with one clade containing Hemienchytraeus and Achaeta, the other the remaining 12 genera analysed. The latter group is basally resolved in several well-supported clades. Lumbricillus and Grania are closely related. Bryodrilus, Oconnorella, Henlea and two species of Marionina (M. cf. riparia, and M. communis) form a well-supported clade. Cognettia is sister to Stercutus, and Cernosvitoviella sister to Mesenchytraeus, and the four together appear to be a monophyletic group. A large part of the taxonomically problematic Marionina appears to be a group not closely related to the type species (M. georgiana), and this group also includes Enchytronia. Further, this Marionina/Enchytronia group appears to be sister to a clade comprising the more or less littoral marine genera Stephensoniella and Enchytraeus. Hemifridericia, Buchholzia and Fridericia, the three genera characterized by two types of coelomocytes, also form a well-supported clade. The study corroborates most of the multi-species genera analysed (Cognettia, Cernosvitoviella, Mesenchytraeus, Oconnorella, Henlea, Enchytraeus, Grania, Buchholzia and Fridericia); only Lumbricillus and Marionina are non-monophyletic as currently defined., (Copyright © 2010 Elsevier Inc. All rights reserved.)