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- Erséus, Christer, 1951, et al.
(författare)
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The popular model annelid Enchytraeus albidus is only one species in a complex of seashore White Worms (Clitellata, Enchytraeidae)
- 2019
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Ingår i: Organisms Diversity & Evolution. - : Springer Science and Business Media LLC. - 1439-6092 .- 1618-1077. ; 19:2, s. 105-133
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Tidskriftsartikel (refereegranskat)abstract
- The white worm Enchytraeus albidus Henle, 1837 (Clitellata, Enchytraeidae) is easy to keep in laboratory cultures, and has therefore been employed as a model organism in basic and applied biological research. Its natural habitat includes terrestrial composts and wrack beds on seashores. However, the name E. albidus is currently used for a complex of morphologically similar and closely related species. We here revise the components of the E. albidus species complex based on a sample of 100 Enchytraeus specimens from 56 sites, most of which are across Europe. These samples were DNA-barcoded for the mitochon- drial COI gene. A subset of them was sequenced for the nuclear ITS2 and H3 markers. Six species were delimited with strong support by the COI and ITS2 gene trees, as well as by a multi-locus species delimitation analysis. These species are identified morphologically and described as E. albidus s. str. (with designation of a neotype); Enchytraeus moebii (Michaelsen, 1885); Enchytraeus albellus Klinth, Erséus and Rota, sp. nov., E. cf. krumbachi (Čejka, 1913), E. sp. 1 (unnamed), and Enchytraeus polatdemiri Arslan and Timm, 2018. The last-mentioned species is a soda lake specialist, whereas E. albidus s. str. is both terrestrial and marine littoral; all other species occur only in seashores. The phylogeny of this group was estimated using the multi-species coalescent model. Monophyly of the E. albidus complex was recovered. Within this complex, three groups were recovered as monophyletic, but the relationship between them is unclear. One group comprises E. albidus s. str., E. albellus, and E. moebii; the second group E. cf. krumbachi and the unnamed E. sp. 1, and the third consists of only E. polatdemiri. This study serves as a framework for genetic identification of white worms used for experimental purposes.
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- Martinsson, Svante, 1985, et al.
(författare)
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Placing the forgotten: On the positions of Euenchytraeus and Chamaedrilus in an updated enchytraeid phylogeny (Clitellata : Etraeidae)
- 2017
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Ingår i: Invertebrate Systematics. - 1445-5226 .- 1447-2600. ; 31:1, s. 85-90
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Tidskriftsartikel (refereegranskat)abstract
- The phylogeny of Enchytraeidae was re-estimated to establish the relationships of the now resurrected Chamaedrilus and Euenchytraeus and to confirm their status as separate taxa. The former Cognettia (Enchytraeidae) was recently revised and split into its two senior synonyms, Chamaedrilus and Euenchytraeus, with the majority of the species transferred to Chamaedrilus. Euenchytraeus was re-established for three species sharing a unique anatomical trait, but has never before been represented in any phylogenetic study. We included representatives from 21 (of 33) valid enchytraeid genera and used three mitochondrial and four nuclear genes. The dataset (4164 base pairs) was analysed using multi-species coalescent (MSC) and maximum likelihood (ML) methods. Chamaedrilus (represented by eight species) and Euenchytraeus (represented by Eu. clarae) were found in a clade together with the monotypic Stercutus. Chamaedrilus was found to be monophyletic with maximum support in both analyses. The ML tree supported Euenchytraeus and Chamaedrilus as sister groups, whereas the MSC tree placed Euenchytraeus together with Stercutus, both with low support. A Bayes factor test weakly supported Euenchytraeus and Chamaedrilus as sister groups over Euenchytraeus + Stercutus. Possible morphological synapomorphies for these genera are discussed, and we conclude that Chamaedrilus and Euenchytraeus are closely related, but their status as separate genera is justified.
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- Martinsson, Svante, 1985, et al.
(författare)
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Revision of Cognettia (Clitellata, Enchytraeidae): re-establishment of Chamaedrilus and description of cryptic species in the sphagnetorum complex
- 2015
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Ingår i: Systematics and Biodiversity. - : Informa UK Limited. - 1477-2000 .- 1478-0933. ; 13:3, s. 257-277
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Tidskriftsartikel (refereegranskat)abstract
- The oligochaete worm, Cognettia sphagnetorum (Vejdovský, 1878), is widely used as a model organism in soil biology, and therefore it is important that its taxonomy is firmly established. A previous study based on both mitochondrial and nuclear genetic markers showed that this taxon is an assemblage of at least four species that do not form a monophyletic group. Also the validity of the genus Cognettia Nielsen and Christensen, 1959 is subject to debate, since the existence of two putative senior synonyms, Euenchytraeus Bretscher, 1906 and Chamaedrilus Friend, 1913 has been pointed out. Herein we revise the generic assignment of the species currently placed in Cognettia: two species, C. clarae Bauer, 1993 and C. piperi Christensen and Dózsa-Farkas, 1999, are transferred to Euenchytraeus, together with its type Eu. bisetosus Bretscher, 1906, whereas the remaining species, including Cognettia sphagnetorum, are being transferred to Chamaedrilus. Five species within the Chamaedrilus sphagnetorum complex are revised: the type species of Chamaedrilus, Ch. chlorophilus Friend, 1913, as well as the type species of Cognettia, Ch. sphagnetorum s. str. are redescribed, and a neotype is designated for the latter; and the cryptic species Ch. pseudosphagnetorum sp. nov. and Ch. chalupskyi sp. nov. are described as new to science and discussed against a paratype of Ch. valeriae (Dumnicka, 2010) comb. nov. DNA-barcodes are provided for all the named species in the complex except Ch. valeriae. A key to the species in the complex is given and the value of different somatic characters for separating and identifying species of Chamaedrilus is discussed. No morphological feature seems to distinguish Ch. sphagnetorum from Ch. pseudosphagnetorum. Thus, for a reliable identification of these species, molecular methods, e.g. DNA barcoding, are recommended.
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- Matamoros, Lisa, 1979, et al.
(författare)
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Cryptic diversity among the achaetous Marionina (Annelida, Clitellata, Enchytraeidae)
- 2012
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Ingår i: Systematics and Biodiversity. - : Informa UK Limited. - 1477-2000 .- 1478-0933. ; 10:4, s. 509-525
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Tidskriftsartikel (refereegranskat)abstract
- This study investigates the diversity and taxonomy of a mainly marine group of species lacking chaetae currently assigned to the genus Marionina. This achaetous group includes four nominal species: M. achaeta (Hagen, 1954), M. achaeta sensu Lasserre, 1964, M. nevisensis Righi & Kanner, 1979 and M. arenaria Healy, 1979. As Lasserre's (1964) M. achaeta appears to be morphologically different from its (then) senior homonym M. achaeta (Hagen, 1954), the replacement name M. nothachaeta nom. nov. is proposed for it. We studied the genetic and morphological diversity of achaetous specimens of Marionina collected in Florida, the Great Barrier Reef, New Caledonia, Sweden, England and the Bahamas. The collection localities are almost all supralittoral and often brackish-water habitats. Parts of the mitochondrial genes 12S, 16S, COI and the nuclear genes 18S, 28S and ITS were analysed to assess the genetic variation and phylogeny of the achaetous Marionina species. The molecular data reveal one monophyletic group of 11 separately evolving lineages, and between these lineages, K2P distances in the barcoding gene COI vary between 5.4 and 25.0%. On a morphological basis, the lineages could be assigned to seven different groups (morphotypes), of which only two could be identified as described nominal taxa: M. nevisensis s. lat. (several lineages) and M. nothachaeta. Since the former taxon appears to be a complex of cryptic species around the world and the original type material no longer exists, a neotype from the Caribbean was designated for M. nevisensis s. str. The remaining achaetous lineages represent five morphologically distinct species that are left unnamed, awaiting finer morphological scrutiny and detailed comparisons with new collections of M. achaeta and M. arenaria. Summing up, the group of achaetous Marionina now seems to contain up to 13 different species, seven of which are yet to be formally described and named.
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