A proposed order-level classification in Oligochaeta (Annelida, Clitellata)

The purpose of our contribution is to propose a robust and practical order-level classification of the families of Oligochaeta, that is, non-leech Clitellata. The order level is mandatory in Linnaean rank-based classification and is also required in many internet-based biodiversity databases. However, it has received little attention in oligochaete systematics, and the few available order-level classifications of Oligochaeta no longer represent phylogenetic relationships adequately. Our proposal is based on corroborated molecular phylogenetic evidence and takes as benchmarks class level for Clitellata, subclass level for Oligochaeta and Hirudinea, and order level for Crassiclitellata, the monophylum that includes most of the earthworm taxa. As a result, eleven orders are proposed: A lluroididA Timm & Martin, 2015; CApilloventridA Timm, n. ordo; CrAssiClitellAtA Jamieson, 1988; enChytrAeidA Kasprzak, 1984; hAplotAxidA Brinkhurst & Jamieson, 1971; lumbriCulidA Brinkhurst & Jamieson, 1971; moniligAstridA Brinkhurst & Jamieson, 1971; nArApidA Timm, n. ordo; pArvidrilidA Timm, n. ordo; rAndiellidA Jamieson, 1988; tubifiCidA Jamieson, 1978. This order-level classification is robust and easily adaptable to future insights into phylogenetic relationships

The popular model annelid Enchytraeus albidus is only one species in a complex of seashore white worms (Clitellata, Enchytraeidae)

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Clitellate worms (Annelida) in late-glacial and Holocene sedimentary DNA records from the Polar Urals and northern Norway

While there are extensive macro‐ and microfossil records of a range of plants and animals from the Quaternary, earthworms and their close relatives amongst annelids are not preserved as fossils and therefore the knowledge of their past distributions is limited. This lack of fossils means that clitellate worms (Annelida) are currently underused in palaeoecological research, even though they can provide valuable information about terrestrial and aquatic environmental conditions. Their DNA might be preserved in sediments, which offers an alternative method for detection. Here we analyse lacustrine sediments from lakes in the Polar Urals, Arctic Russia, covering the period 24 000–1300 cal. a BP, and NE Norway, covering 10 700–3300 cal. a BP, using a universal mammal 16S rDNA marker. While mammals were recorded using the marker (reindeer was detected twice in the Polar Urals core at 23 000 and 14 000 cal. a BP, and four times in the Norwegian core at 11 000 cal. a BP and between 3600–3300 cal. a BP), worm extracellular DNA ‘bycatch’ was rather high. In this paper we present the first reported worm detection from ancient DNA. Our results demonstrate that both aquatic and terrestrial clitellates can be identified in late‐Quaternary lacustrine sediments, and the ecological information retrievable from this group warrants further research with a more targeted approach.publishedVersio

DNA Barcoding Reveals Cryptic Diversity in Lumbricus terrestris L., 1758 (Clitellata): Resurrection of L. herculeus (Savigny, 1826)

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

The Magnitude of Global Marine Species Diversity

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

Doliodrilus ciliatus Wang & Erséus 2004, sp. n.

Doliodrilus ciliatus sp. n. (figure 4) Holotype. IHB HANA2000023 b, whole-mounted specimen. Type locality. China, northern Hainan, mangroves of Dong Zhai Harbour nature reserve (Station HU00-14B). Etymology. The specific name ciliatus is Latin for ‘furnished with cilia’ and refers to the ciliated atria. Description. Specimen complete, 12.0 mm, 69 segments. Diameter at XI 0.5 mm. Prostomium conical. Clitellum extending over XI–1/2XII. Chaetae bifid, with upper teeth about twice as long as lower (figure 4A). Chaetae 70–85 m m long, about 2.5 m m thick; two to five per bundle anteriorly, two to three per bundle in post-clitellar segments. Ventral chaetae absent in XI. Male pores paired, in line with ventral chaetae in posterior part of XI (figure 4B). Spermathecal pores paired, in line with ventral chaetae in X, at about one-third of segment from anterior septum (figure 4B). Pharyngeal glands well developed in IV– V. Chloragogen cells from VI onwards. Anterior third of oesophagus in IX unmodified, with wall only 25–35 m m thick. Posterior two-thirds of oesophagus in IX barrel-shaped, granulated, with wall up to 70 m m thick, but without chloragogen cells; semi-embedded blood plexus present, but inconspicuous, with regular transverse vessels and less regular longitudinal ones. Male genitalia (figure 4B) paired. Vas deferens not clearly visible, estimated to be about as long as atrium, entering latter subapically (?). Atrium tubular, totally 230 m m long, 17–27 m m wide; ental part of atrial ampulla densely ciliated, thinwalled and somewhat dilated; ectal part of ampulla more thick-walled, and with wall containing more nuclei (figure 4B: aa). Prostatic pad (ppd) oval, 31 m m long, ventrally situated, bulging out from middle of atrium. Prostate gland (pr) large, with small nuclei and large nucleus-like bodies, latter oblong, round or irregularly polygonal, maximally 14 m m long, 10 m m wide. Atrial duct (figure 4B: ad) with (1) posterior blind sac (bs), about 30 m m long, 10–15 m m wide, and (2) short efferent duct (ed), about 30 m m long, 25 m m wide, opening directly to exterior through simple pore. Sperm sac extending through IX–X. Egg sac in XII–XIII. Spermathecae (figure 4B: s) club-shaped; ducts 110 m m long, 27–34 m m wide, with small, but distinct ectal vestibules; ampullae oval, thin-walled, 120 m m long, up to 77 m m wide, with sperm bundles in lumina. Remarks. Initially, we hesitated to assign this species to the genus Doliodrilus, as the ental parts of its atria are ciliated, a character formerly considered to be an autapomorphy of Smithsonidrilus Brinkhurst, 1966 (Limnodriloidinae) (Erséus, 1990b). However, D. ciliatus has a dilated oesophagus in segment IX, and although indistinct, there is an oesophageal blood plexus in this segment. This type of modification as well as the atrial blind sacs are characteristic of most Doliodrilus, and thus, it is reasonable to conclude that this species belongs to the latter genus. With regard to the chaetal morphology and male ducts, D. ciliatus appears to be closely related to D. longidentatus sp. n. described above, but it is easily differentiated from the latter and other congeners by its ciliated atria, and the short length of the modified part of the oesophagus in segment IX. Distribution and habitat. Known only from type locality, southern China. Lower intertidal in mangroves, clay and mud.Published as part of Wang, Hongzhu & Erséus, Christer, 2004, New species of Doliodrilus and other Limnodriloidinae (Oligochaeta, Tubificidae) from Hainan and other parts of the north-west Pacific Ocean, pp. 269-299 in Journal of Natural History 38 (3) on pages 278-279, DOI: 10.1080/0022293021000028252, http://zenodo.org/record/525861