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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.

Rhyacodrilus tanggulaensis Jiang & Cui, sp. nov. Holotype. IHB TTH20170720 a, mature specimen, stained and whole-mounted in Canada balsam. Type locality. Tongtian River (34.1084 N, 95.7199 E), Yushu City, Qinghai province, China. Elevation 4077 m a.s.l, water temperature 15.3 °C, pH 8.3, dissolved oxygen 7.1 mg. l-1, conductivity 801 μS/cm. Collected by Yongde Cui and Tingting Zhou on 20 July 2017. Paratypes. IHB XZ20200903 b, 1 mature specimen whole-mounted in Canada balsam, Nagqu river in Tibet (31.6574 N, 92.0219 E). Elevation 4586 m a.s.l., water temperature 12.3 °C, pH 8.7, dissolved oxygen 6.1 mg. l-1, and conductivity 485 μS/cm. Collected by Yongde Cui, Tingting Zhou and Wei Jiang on 09 September 2020. Other material. 3 specimens from the Nagqu River for scanning electron microscopy. The species was also observed, but not studied in detail, in Za’gya Zangbo River. Etymology. Named tanggulaensis after the Tanggula Mountains. The rivers where the specimens were collected are all related to the Tanggula Mountains. Description. Length about 8–9 mm, width at genital segments X–XI about 0.5–0.6 mm. Segments 35–45. Prostomium round. Coelomocytes large, abundant, granulated, diameter 8–16μm. Clitellum extending over 1/2X–XI. Dorsal and ventral bundles with 4–5 bifid chaetae, 75–90 μm long, 2–3 μm wide, distal tooth 2–3 times longer than proximal (Figs. 1A, 2A, B). Hair chaetae absent. Modified spermathecal chaetae in segment X (Figs. 1B, 2D), 1–2 per bundle, 75–100 μm long, 4–5 μm wide, bifid with very long, sharply-pointed distal tooth and rounded proximal end. The same kind of chaetae present in IX and XII. Penial chaetae in XI, 4 per bundle, 75–100 μm long, 4–5 μm wide, single-pointed with slightly curved tips (Fig. 2C). Male pores paired, close to the mid-ventral line of the body, immediately anterior to penial chaetae in XI. Spermathecal pores paired, in line with ventral chaetae, immediately anterior to spermathecal chaetae in X. Male genitalia paired in X–XI (Fig. 1C). Sperm funnel cup-shaped. Vas deferens 1–1.5 mm long, 13–15 μm wide, joining the atrial ampulla subapically. Atrium elongated, 0.7–1 mm long, 70–82 μm wide, roughly tubular, covered by a continuous thick layer of prostatic cells. Atrial duct 300–400 μm long, 25–30 μm wide, with a tortuous lumen. Spermathecae 250–300 μm long, 100–110 μm wide, with short ducts; large masses of randomly arranged sperm in lumina. Distribution and habitat. Known only from Qinghai-Tibet Plateau, in rivers> 4000m above sea level. Some rivers are at the foot of snow mountain (Fig. 3). The sampling area is surrounded by natural plateau grassland. The collection site is a shallow permanent stream with gravel and cobbles sediment. Remarks. Genus level. Morphologically, the new species belongs to the genus Rhyacodrilus based on the presence of spermathecal and penial chaetae, the rich occurrence of coelomocytes, the vas deferens being longer than the atrium and joining it subapically, and the continuous coverage of the atrium with a layer of prostate cells (Brinkhurst & Jamison 1971). Species level. In Rhyacodrilus there are currently 11 species which possess both spermathecal and penial chaetae; they are listed in Rodríguez & Fend (2013, Table 1). Among them, three species are devoid of hair chaetae, R. carsticus Košel, 1980, R. gernikensis Giani & Rodriguez, 1988, and R. ardierae Lafont & Juget, 1993. A comparison of these species with Rhyacodrilus tanggulaensis sp. nov. is given in Table 3. Some obvious differences are as follows: R. carsticus and R. ardierae have globular to oval atria (elongate-tubular in the new species), and R. gernikensis has unmodified genital chaetae and a pear-shaped atrium (see Giani & Rodríguez 1988; Rodríguez & Fend 2013, Achurra & Rodríguez 2016). Geographical distribution. R. ardierae, R. carsticus and R. gernikensis are only known from groundwater habitats at a few sites in western to central Europe (Achurra & Rodriguez 2016). The new species described here is only distributed in rivers above 4000 m elevation on the Qinghai-Tibet Plateau. In this area the river sediments are mainly composed of clean sand and gravel. It is worth noting that the highest distribution is 5263 m above sea level, a locality near Tanggula Mountain, the source of Za’gya Zangbo, Tibet's largest inland river., Published as part of Jiang, Wei, Zhou, Tingting, Wang, Hongzhu, Erséus, Christer & Cui, Yongde, 2023, Integrative taxonomy of a new species of Rhyacodrilus (Annelida: Clitellata: Rhyacodrilinae) from Tibet Plateau rivers, with a preliminary assessment of its phylogenetic position, pp. 125-138 in Zootaxa 5256 (2) on pages 130-131, DOI: 10.11646/zootaxa.5256.2.2, http://zenodo.org/record/7746357, {"references":["Rodriguez, P. & Fend, S. V. (2013) New species of Rhyacodrilus (Annelida: Clitellata: Rhyacodrilinae) of North America, with re-description of R. sodalis (Eisen, 1879). Zootaxa, 3664 (1), 1 - 44. https: // doi. org / 10.11646 / zootaxa. 3664.1.1","Kosel, V. (1980) Rhyacodrilus carsticus sp. n. (Oligochaeta, Tubificidae) from the Slovakian Karst. Biologia 35, 609 - 612.","Giani, N. & Rodriguez, P. (1988) Description de quelques especes nouvelles de Tubificidae (Oligochaeta) de grottes et de sources karstiques de la peninsule iberique. Stygologia, 4, 122 - 137.","Lafont, M. & Juget, J. (1993) Rhyacodrilus ardierae n. sp., a new species of Tubificidae (Oligochaeta) from the River Ardieres (France, tributary of the River Saone). Bulletin de la Societe Zoologique de France, 118, 115 - 123.","Achurra, A. & Rodriguez, P. (2016) Syntopy in subterranean fauna: trophic specialisation in two new species of Rhyacodrilus Bretscher, 1901 (Annelida, Clitellata, Rhyacodrilinae). Zoologischer Anzeiger - A Journal of Comparative Zoology, 261, 1 - 11. https: // doi. org / 10.1016 / j. jcz. 2016.02.001"]}

A new oligochaete of the family Naididae, subfamily Naidinae, Bratislavia gusevi sp. n., was found in a forest stream in Vietnam. The worm is characterized by small size, asexual reproduction by fragmentation, and dorsal bundles of chaetae beginning from segment II. Each dorsal bundle bears one to two hairs and one to two simple-pointed or bifid, rarely trifid, needle chaetae. An additional distinctive feature of the worm is the presence of one to two enlarged simple-pointed needle chaetae in the bundles of segment IV. These chaetae are somewhat longer and markedly wider than the needles in the rest of the segments. The present paper provides an illustrated description of the discovered individuals and discusses the species’ systematic position, asexual reproduction and regeneration.

Despite their great interest for the integrated management of water resources, information on the ecology of aquatic oligochaetes is still sketchy in Cameroon. The present study aims at contributing to the knowledge on the distribution, microhabitat and life history of Naididae tubificids taxa in some eight water bodies of the city of Yaounde. A total of 132 samples were analysed and the morphospecies Branchiura spp. and Limnodrilus spp. were identified. The most abundant species were Branchiura spp. with 2035 individuals versus 880 Limnodrilus spp. Both of them demonstrate low seasonal variations. It appeared that, these annelids are more abundant on clay-rich soils than on sand and the herbarium. Assessment of the organic pollution index indicates an organic pollution of the sampled waters ranging from moderate to high (3.67-2). The redundancy canonical analysis shows that Branchiura spp. are more present in saline waters revealing high organic pollution factors variables. During the study period, some 10 individuals of Limnodrilus spp. presented a shrunken tail. That reveals a strong environmental pressure due to the action of predators or the presence of heavy metals in the aquatic system evaluated. All these characteristics indicate a high pollution and predation pressure in the milieu. Key words: Annelids oligochaete, ecology, bottom nature, polluted water.

During studies of aquatic fauna in wells situated near Kraków (South Poland), many specimens of clitellates were found. The detailed description of the setal formula and genital organs of the collected individuals made it possible to distinguish Haber zavreli (Hrabĕ, 1942) from the related species: H. speciosus (Hrabĕ, 1931) including synonymized H. simsi and its forms known from the USA (H. speciosus simsi and H. speciosus fluminialis) and H. monfalconensis (Hrabĕ, 1966). In addition, remarks concerning the morphologically similar Haber vetus (Semernoy, 1982) described from Lake Baikal and the stygobiotic species H. turquinae (Juget & Lafont, 1979) are included.

Pristina (Pristina) synclites (Pristinide) and rare Bratislavia palmeni (Naididae), collected from Hemşin Stream (Rize-Pazar; part of the lower Yeşilırmak River System) and Lake Çıldır respectively, are new records for the Turkish Oligochaeta fauna. In addition, the genus Bratislavia is also new for the Anatolian fauna., Hemşin Deresi’nden (Rize-Pazar; Aşağı Yeşilırmak Nehir Sistemi’nin parçası) toplanan Pristina (Pristina) synclites and Çıldır Gölü’nden toplanan nadir Bratislavia palmeni Türkiye Oligochaeta faunası için yeni kayıtlardır. Ayrıca, Bratislavia cinsi de Anadolu faunası için yeni kayıt niteliğindedir.

The International Code of Zoological Nomenclature (Anonymous 1999; ‘the Code’ below) provides Rules for the nomenclature of the ‘names of the group family’, or family-series nomina (Dubois 2000). These Rules have long been ignored or disregarded by some taxonomists, so that the authorship(s) and date(s) currently attached in the literature and in some taxonomic online databases to some family-series nomina of Annelida Oligochaeta[1] prove to be wrong according to the Code. For example, the database Taxonomicon credits the nomina Naididae to Ehrenberg (1828), Tubificidae to Vejdovský (1876), Enchytraeidae to Vejdovský (1879) and Lumbriculidae to Vejdovský (1884a). Vejdovský (1884b: 59) also claimed authorship for the nomen Lumbricidae. All of these attributions are incorrect, as will be established below through a chronological survey of the relevant works where these nomina were made available. [1] The nomen Oligochaeta is here used in its original sense (Grube 1850), i.e. excluding the Hirudinea.

Myxobolus cerebralis (Hofer, 1903), the etiological agent of salmonid whirling disease, reportedly matures in only the oligochaete ‘Tubifex tubifex’. The concept of ‘T. tubifex’ is problematic because it is renowned as a species complex (or having ‘strains’), and many sequences ascribed to this taxon in GenBank are misidentified or indicate several cryptic species. These facts cast doubt on the long-held notion that M. cerebralis is strictly host-specific to the single definitive host, T. tubifex. Herein, as part of an ongoing regional whirling disease monitoring project, oligochaetes (452 specimens) were collected from 31 riverine sites in western North Carolina (August through September 2015) and screened for infection by M. cerebralis. The species-specific nested PCR for M. cerebralis was positive for 8 oligochaete specimens from the French Broad River Basin (Mill Creek and Watauga River) and New River Basin (Big Horse Creek). We individually barcoded these M. cerebralis-positive oligochaete specimens using cytochrome oxidase 1 (CO1) primers and then conducted a Bayesian inference phylogenetic analysis. We identified 2 oligochaete genotypes: one sister to a clade comprising Limnodrilus udekemianus (Haplotaxida: Naididae) and another sister to Limnodrilus hoffmeisteri. This is the first detection of M. cerebralis from an oligochaete in the SE USA and the first detection of M. cerebralis from an oligochaete other than T. tubifex. These results suggest that other non-T. tubifex definitive hosts can harbor the pathogen and should be considered in the context of fish hatchery biosecurity and monitoring wild trout streams for M. cerebralis and whirling disease in the southeastern USA.

Pristina multiseta sp. nov. (Figs 1–4) Material examined. Holotype. NSMT-An 1876, a sexually mature specimen whole-mounted on slide, 15 July 2007, coll. A. Ohtaka. Type locality. Paddy field in Nagayama, Shizukuishi Town, Iwate Prefecture, Japan (39.7469°N, 140.9644°E). Paratypes. NSMT-An 1877, a whole-mounted mature specimen; NSMT-An 1878, a sagittally-sectioned mature specimen; locality, date and collector the same as for the holotype. Other material examined. 12 sexually mature and one immature specimens mounted on slides and three mature, sagittally-sectioned specimens; locality, date and collector the same as for the holotype. Three mature and two immature specimens from a paddy field in Hata, Takashima City, Shiga Prefecture, Japan (35.2923°N, 135.9339°E), 24 July 2015, coll. M. J. Grygier. Etymology. The specific name refers to high number of dorsal chaetae in the present species. Diagnosis. Body length of single zooid 1.5–3.0 mm in fixed state. Prostomium forming a short proboscis. Dorsal chaetal bundles with 3–5 smooth hairs and 2–5 shortly bifid needles in anterior segments. Ventral chaetae in IV through VII enlarged. No modified genital chaetae. Stomach widening in anterior half of VIII, lined with column-shaped and glandular epithelium embedded in a blood plexus. Male duct with short vas deferens and tubular atrium, opening ventrolaterally in VIII. Blood vessels surrounding ectal half of atrium. Spermatheca with large ampulla and short and conical duct, opening on the chaetal line behind 6/7. Description. In fixed state, body length 1.5–3.0 mm, width 0.15–0.25 mm at clitellum and 0.13–0.17 mm at middle of body, 25–34 segments. No budding zone observed. No eyes. Prostomium forming a short proboscis (Fig. 1A–D): length 24–61 µm, diameter 10–16 µm, shorter than frontal width of segment I. Segments II to VI biannulate (Fig. 1A), each with short anterior and long, chaetaebearing posterior annuli. Genital segments longer than nongenital ones. Clitellum conspicuous, from 2/3 VII to end of IX; ventral side of body in VIII–IX indented longitudinally and slightly swollen at male pores laterally in VIII (Fig. 1A). Body wall 3–6 µm thick except for clitellum which has up to 10 µm high glandular epidermis. Coelomocytes scattered throughout the segments, spherical, 4–5 µm in diameter. Pharynx in II and III, dorsal wall up to 7 µm thick, slightly thicker than ventral wall (Fig. 1E). Pharyngo-esophageal glands developed dorsally in II–IV, each 12–15 µm high (Fig. 1E). Esophagus in IV through VII, 15–24µm wide with wall 4–6 µm thick. Esophagus widening and forming stomach in anterior half of VIII. Stomach gradually (Fig. 1E) or abruptly widening (Fig. 4A), up to 80–96 µm wide and lined with glandular and column-shaped inner epithelium, 20–25µm tall and 3–5 µm wide (Fig. 1F). Blood vessels developed on stomach, penetrating epithelium between the individual cells of the stomach. From IX on gut 70–100 µm wide with thin (5–8µm thick) wall. Chloragocytes beginning in V with single cells of less than 8 µm high, covering the alimentary canal. Transverse vessels forming loops in IV–VI (Fig. 1E). Dorsal chaetal bundles (Fig. 2A) consisting of hair and needle chaetae, both beginning in II. Hair chaetae smooth under examination with 1000× using oil immersion lens, 3–5 per bundle, 106–200 µm long in preclitellar segments; 1–3 per bundle, 64–170 µm long in postclitellar ones. Dorsal needle chaetae bayonet-shaped, with inconspicuous nodulus, weakly bent at 1/4 from the distal end (Fig. 2B), 2–5 per bundle, 35–50 µm long in preclitellar segments; 1–2 per bundle, 30–45 µm long in postclitellar ones. Distal ends of dorsal needle chaetae shortly bifid and slightly divergent; length of teeth almost as long as chaetal width. Upper teeth of dorsal needle chaetae as long as or a little longer and as thick as or a little thinner than weakly bent lower teeth (Fig. 2C, D). No intermediate teeth on dorsal needle chaetae. Ventral chaetae all bifid crotchets with slightly distal nodulus (Fig. 2E–K). In sexually mature worms, those in II and III smaller than those in the following segments, 3–6 per bundle, 48–56 µm long, upper tooth slightly longer and almost as thick as lower one (Fig. 2E, F); those in IV–VII longer and thicker than those in the rest of segments (Fig. 2G–J), 2–5 per bundle, 60–70 µm long, 2.0–2.5 µm thick, distal teeth longer and almost as thick as lower ones; ventral chaetae in IV and VII longer and thicker than those in V and VI, with distal teeth 1.5 to 2 times longer than lower teeth; ventral chaeta from VIII on 2–5 per bundle, 48–55 µm long, upper teeth as long as or a little longer and slightly thinner than lower ones (Fig. 2K). No modified genital chaetae at genital pores. No chaetophorous or associated glands in any ventral chaetal bundles. In immature worms, ventral chaetae in anterior segments 2–5 per bundle, 40–49 µm long, not especially longer or thicker in IV–VII; upper tooth almost as long as or a little longer and and almost as thick as lower. Gonads and copulatory organs paired. Testes in VII, ovaries in VIII. Male funnels on anterior face of 7/8, 30–40 µm in diameter (Figs 3, 4B). Vasa deferentia about 45 µm long, 6–8 µm thick, not winding, covered with glandular, 8–10 µm high, prostate cells, connected with atria apically (Fig. 3). Atria tubular, 50–64 µm long, 20–25 µm wide, with thick and glandular inner epithelium and thin muscular cover (Figs 3, 4B). Several thin blood vessels 1.5–2.2 µm in diameter surrounding ectal half of atria (Figs 3, 4C); it is unclear that they are arranged spirally or several circles separate from each other. Ejaculatory ducts not detected and male pores opening on papillae ventrolaterally in anterior part of VIII. Spermathecae in VII (Fig. 3); spermathecal ampullae large and ovoid, 64–128 µm long, 58–96 µm wide, with thin wall; spermathecal ducts well-distinguished from ampullae, short and conical, 16–18 µm long, 14–18 µm wide at junction with ampullae, opening on the chaetal line slightly behind anterior septa (Fig. 3). Loose sperm present in spermathecal ampullae. Sperm sac in VII–VIII. Egg sac in VIII–X. Variations. Length of proboscis varied from one forth to almost equal to frontal width in segment I (Fig. 1A–D). All sexually mature specimens examined (n=15) had enlarged ventral chaetae in IV through VII, and those in IV and VII were invariably larger than those in V and VI. The enlargement of ventral chaetae in V and/or VI varied from slightly larger than in II and III to nearly as large as in IV or VII. All sexually immature specimens examined had ventral chaetae of normal size, not larger than the rest. Distribution and habitat. The new species was collected from bottom surfaces of two inundated paddy fields in north and central parts of Japan, with water depth of both localities less than 10 cm. At the type locality in Iwate Prefecture, north Japan, three tubificines, Aulodrilus limnobius Bretscher, 1899, A. pigueti Kowalewski, 1914, Limnodrilus hoffmeisteri Claparède, 1862, and two naidines, Nais pardalis Piguet, 1906 and Slavina appendiculata (d’Udekem, 1855), were found together with the present species., Published as part of Ohtaka, Akifumi, 2022, Pristina multiseta sp. nov. (Annelida: Clitellata: Oligochaeta: Naididae: Pristininae) from Paddy Fields in Japan, pp. 95-100 in Species Diversity 27 (1) on pages 95-98, DOI: 10.12782/specdiv.27.95, http://zenodo.org/record/7175499, {"references":["Piguet, E. 1906. Observations sur les Naididees et revision systematique de quelques especes de cette famille. Revue Suisse Zoologie 14: 185 - 315."]}

Ohtaka, Akifumi (2022): Pristina multiseta sp. nov. (Annelida: Clitellata: Oligochaeta: Naididae: Pristininae) from Paddy Fields in Japan. Species Diversity 27 (1): 95-100, DOI: 10.12782/specdiv.27.95, URL: http://dx.doi.org/10.12782/specdiv.27.95

Four new actinospore types belonging to the sphaeractinomyxon collective group (Cnidaria, Myxosporea) are described from the coelomic cavity of a marine Baltidrilus sp. (Oligochaeta, Naididae) inhabiting a northern Portuguese estuary. Host identification supports the usage of marine oligochaetes, namely of the family Naididae Ehrenberg, 1828, as definitive hosts for myxosporeans inhabiting estuarine/marine environments. The absence of mixed infections in the host specimens analysed is suggested to reflect the influence of host-, parasite- and environmental-related factors regulating myxosporean–annelid interactions. Molecular analyses matched the SSU rDNA sequences of three of the four new types with those of mugiliform-infecting Myxobolus spp., namely Myxobolus mugiliensis and a Myxobolus sp. from flathead grey mullet Mugil cephalus, and Myxobolus labrosus from thicklip grey mullet Chelon labrosus. These results directly link, for the first time, the sphaeractinomyxon collective group to a myxospore counterpart, further confirming their previously hypothesized specific involvement in the life cycle of myxobolids that infect mullets. Acknowledging this life cycle relationship, the functionality of the sphaeractinomyxon morphotype is suggested to have been decisive for the evolutionary hyperdiversification of the genus Myxobolus in mullets. Unlike other actinospore morphotypes, sphaeractinomyxon lack valvular processes, which implies a limited capability for buoyancy. Considering the benthic-feeding nature of mullets, this feature is most likely crucial in promoting successful transmission to the vertebrate host.

One of the features of the tundra zone is the diversity of freshwater bodies, where, among benthic invertebrates, representatives of Annelida are the most significant component in terms of ecological and species diversity. The oligochaete and leech faunas have previously been studied in two of the three largest lake ecosystems of the Bolshezemelskaya tundra (the Vashutkiny Lakes system, Lake Ambarty and some other lakes in the Korotaikha River basin). This article provides current data on annelid fauna from the third lake ecosystem in the region, Kharbey Lakes and adjacent water bodies. The annelid fauna includes 68 species, including 51 oligochaete species, and 17 species of leeches. For each species, we give information on currently recognised classification, taxonomic synonymy, geographical distribution, findings of the species within the Russian tundra, and brief ecological characteristics.

A new species of naidid oligochaete, Dero rwandae, detected in the bladder and the Wolffian ducts of reed frogs Hyperolius kivuensis from Rwanda, is described. Until now, D. bauchiensis was the only endoparasitic Dero known to infect African frogs infesting the eyes and Harderian glands. To the best of our knowledge, the finding of D. rwandae is the first record of an African Dero species infecting the urinary tract of anurans. In general morphology, the two African Dero parasites resemble each other, but differences in the features of ventral setae morphology exist. Parts of the mitochondrial 16S rRNA locus and the nuclear 18S and 28S rRNA loci were sequenced to assess the phylogenetic relationships to other Dero spp. Among those few species, that are barcoded so far, the closest relative of the new taxon is D. superterrenus, a free-living South American species. The species groups formerly termed subgenera Allodero, Aulophorus and Dero within the genus Dero do not represent distinct evolutionary lineages and the genus is paraphyletic including Branchiodrilus.

Limnodrilus paraclaparedianus Zhou & Cui n. sp. (Figures 4���6) Limnodrilus ��� claparedianus-cervix ���. Liu et al. 2017a: p. 483f., Fig. 3, Supplementary document S1, Suppl. Table S1, Suppl. Fig. S2, S 3, S 5. Liu et al. 2017b: Table 1, p. 251f. Holotype. IHB HB20171202 a (CW0008), whole-mounted specimen, mature, stored at Institute of Hydrobiology, Chinese Academy of Sciences. Collected in the bottom sludge of Donghu Lake, Wuhan, Hubei (GPS: 114.352˚ E/30.535˚ N). COI barcode: GenBank MT 460105. Paratype. IHB HB20171202 b, whole-mounted specimen, mature, from type locality. Other material. 1 specimen for SEM (Fig. 4), from type locality; IHB AH20171211 a���b (CW0009���CW0010), 2 mature specimens from Longganhu Lake, Anhui; IHB AH20171123 a (CW0011), 1 mature specimen from Huaihe River, Anhui; IHB JS20181130 a (CW0018), 1 mature specimen from Taihu Lake, Jiangsu. For more details see Table 1. Etymology. Named ��� paraclaparedianus ��� for the resemblance with ��� Limnodrilus claparedianus Ratzel, 1868 ��� in terms of the male genitalia. Description. Length 18.00��� 19.25 mm (fixed worms), first XII segments 2.85���3.30 mm (Holotype 2.85 mm), width at clitellum 0.42���0.54 mm (Holotype 0.42 mm), segments 80���95 (Holotype 80). Prostomium conical (Fig. 4A). Clitellum inconspicuous. All chaetae bifid (Figs. 4C���F, 5A���D). Anterior bundles with 4���7 chaetae, length 80���125 ��m, width 2.5���3.7 ��m, nodulus 1/3 from the distal end. 3���4 chaetae per bundle in mid-body, 1���2 per bundle in posterior segments. Upper tooth slightly longer than lower in anterior chaetae, thereafter progressively equal-to-shorter than lower towards the posterior part of body. No modified spermathecal chaetae. Spermathecal pores (Fig. 4B) paired ventrally in middle of X; male pores paired ventrally in middle of XI. Chloragogen cells from VI. No coelomocytes. Male genitalia (Fig. 6B) paired. Sperm funnel (Fig. 6B, sf) 90 ��m long. Vas deferens (Fig. 6B, vd) long and coiled, 25���30 ��m wide, entering atrium apically.Atrium (Fig. 6B, at) long, fusiform, 270���300 ��m long, 75���80 ��m wide. Prostate gland (Fig. 6B, pr) large, with irregular lobes, connected to middle of atrium. Ejaculatory duct (Fig. 6B, ed) leading to penis. Penis sheath (Figs. 5E, 6B, ps) long, cylindrical, slender, narrowing from base to head, tapering abruptly with a constriction near the top; the latter bent with a teardrop-shaped plate placed in oblique position; sheath walls not abruptly reduced in thickness at constriction. Penis sheath 620���1030 ��m long, 40���50 ��m wide at base, 15 ��m wide at top, 15���27 times longer than broad. Spermathecal duct (Fig. 6A, sd) 50���56 ��m wide, ampulla (Fig. 6A, sa) difficult to observe but about 340 ��m long, 215 ��m wide in one specimen. Spermatozeugmata (Fig. 6A, sz) about 300 ��m long, 35���60 ��m wide. Distribution and habitat: Species here reported from Provinces Hubei, Anhui, Jiangsu, Shanxi and Heilongjiang in China; also known (as ��� L. claparedianus-cervix ���) from Europe (Germany, Romania) and USA (Liu et al. 2017a). Freshwater. Remarks: This species has the character combination diagnostic of Limnodrilus (Brinkhurst 1971; Liu et al. 2017a, b): no coelomocytes, bifid chaetae only, long vasa deferentia, small atria, large prostates connected to the middle of atria, long ejaculatory ducts, conspicuous cuticular penis sheaths, and presence of spermatozeugmata. Elongate penis sheaths similar to the ones in L. paraclaparedianus are also present in L. maumeensis, L. cervix, L. claparedianus, and in a species of L. hoffmeisteri s.l. (species "III" in Liu et al. 2017a, Fig. 6). Differences of these species to the new one are as follows: In L. maumeensis, the walls of the penis sheaths are conspicuously thickened on one side near the end, causing a bend in the shaft. In L. cervix, the walls of the penis sheaths are conspicuously thickened and abruptly thinner near the end, furthermore, the head has a triangular downward projection. In L. claparedianus, the upper tooth of the anterior chaetae is distinctly longer than the lower. Further subtle differences are the usually larger length/width ratio of the penis sheath (28 and more) and its rounded-triangular (vs. tear-dropshaped) head. In species III of L. hoffmeisteri, the upper tooth of anterior chaetae is much thicker and almost three times longer than the lower; furthermore, the head of the penis sheath is shaped like a plate-top, perpendicular to the long axis of the shaft (comp. Liu et al. 2017a, Fig. 3). The morphological and molecular characteristics of L. paraclaparedianus are identical with those of " L. claparedianus - cervix " described by Liu et al. (2017a), and therefore, we consider them as the same species. With the inclusion of the records in Liu et al. (2017a), it is clear that this new species is Holarctic in distribution., Published as part of Zhou, Tingting, Peng, Yu, Wang, Hongzhu, Ers��us, Christer & Cui, Yongde, 2021, Molecular taxonomy and description of a new species of Limnodrilus (Naididae, Clitellata, Annelida) in China, pp. 301-321 in Zootaxa 5082 (4) on pages 313-316, DOI: 10.11646/zootaxa.5082.4.1, http://zenodo.org/record/5792737, {"references":["Liu, Y. K., Fend, S. V. Martinsson, S. & Erseus, C. (2017 a) Extensive cryptic diversity in the cosmopolitan sludge worm Limnodrilus hoffmeisteri (Clitellata, Naididae). Organisms Diversity & Evolution, 17, 477 - 495. https: // doi. org / 10.1007 / s 13127 - 016 - 0317 - z","Liu, Y. K., Fend, S. V., Martinsson, S., Luo, X., Ohtaka, A. & Erseus, C. (2017 b) Multi-locus phylogenetic analysis of the genus Limnodrilus (Annelida: Clitellata: Naididae). Molecular Phylogenetics & Evolution, 112, 244 - 257. https: // doi. org / 10.1016 / j. ympev. 2017.04.019","Ratzel, V. F. (1868) Beitrage zur anatomischen und systematischen Kenntniss der Oligochaeten. Zeitschrift fur wissenschaftliche Zoologie, 18, 563 - 591, pl. 42.","Brinkhurst, R. O. (1971) Family Tubificidae. In: Brinkhurst, R. O. & Jamieson, B. G. M. (Eds.), Aquatic Oligochaeta of the World. Oliver & Boyd, Edinburgh, pp. 444 - 625.","Brinkhurst, R. O. (1963) Taxonomical studies on the Tubificidae (Annelida, Oligochaeta). Internationale Revue der gesamten Hydrobiologie, Systematische Beihefte, 2, 1 - 89. https: // doi. org / 10.1002 / iroh. 19660510504","Brinkhurst, R. O. & Cook, D. G. (1966) Studies on the North American aquatic Oligochaeta III: Lumbriculidae and additional notes and records of other families. Proceedings of the Academy of Natural Sciences of Philadelphia, 118 (1), 1 - 33."]}

Limnodrilus claparedianus Ratzel, 1868 (Figures 7, 8) Limnodrilus claparedianus Ratzel, 1868: 590, fig. 24; Liu et al. 2017a. Limnodrilus claparedeanus Ratzel. Bretscher 1896: 504. Limnodrilus clapar��deianus Ratzel. Michaelsen, 1900: 45. Limnodrilus claparedeianus Ratzel. Brinkhurst 1971: 468, fig. 8.3; Liang 1987. (Here only different spellings of the same species epitheton are considered. For synonymies and chresonymies see Brinkhurst 1971.) New material from China. IHB SX20181128 a (CW0023), 1 mature specimen from Hanjiang River, Shanxi; IHB JS20191116 a (CW0223), 1 immature specimen from Yixing, Jiangsu; IHB HLJ20191001 a���e (CW0268, CW0270��� 0271, CW0276���0277), 5 immature specimens from Heilongjiang. Description of new material. Length of first 12 segments 2.0��� 4.2 mm, width at clitellum 0.62���0.98 mm. Prostomium rounded (Fig. 7A). Clitellum inconspicuous.All chaetae bifid (Figures 7B,C; 8A,B); upper tooth clearly or slightly longer than, but usually about as thick as lower. Anterior bundles with 4���7 chaetae, 85���110 ��m long, 2.5 ��m wide, and with nodulus 1/3 from distal end. Posterior segments with 1���2 chaetae per bundle. No modified spermathecal chaetae. Spermathecal pores paired ventrally in middle of X; male pores paired ventrally in middle of XI. Chloragogen cells from VI. No coelomocytes. Male genitalia paired. Vas deferens long, entering atrium apically. Atrium small, fusiform. Prostate gland large, connected to middle of atrium. Penis sheath (Fig. 8C,D) elongate, cylindrical, slender, terminal end bent with an angle. Sheath 835 ��m long, 35 ��m wide at its base, 20 ��m wide at the top, 24 times longer than broad in the mature specimen. Spermatheca pear-shaped, with spermatozeugmata. Distribution and habitat. A more or less cosmopolitan species, but here recorded and genetically confirmed from Provinces Shanxi, Jiangsu and Heilongjiang in China. Freshwater. Remarks. In L. claparedianus, the upper tooth of the anterior chaetae is longer than the lower tooth, which is consistent with the description by Brinkhurst (1971). The shape of the apical penis sheath is triangular in L. claparedianus (Ratzel 1868). The same is true of our specimen. Different researchers have concluded that the length: width ratio of the penis sheath varies in this species. Bretscher (1896) found a ratio of 8���10. Brinkhurst (1965), however, noted that the ratio was 17���43. For Chinese specimens, the value was 20 in Nanjing and Nanchang (Chen 1940). This may be due to regional genetic differences or the developmental stage of worms, but it may also be the result of different methods of measuring the sheath by various researchers. Moreover, as indicated above, it may be possible that some of the previous records of alleged L. claparedianus were based on misidentified specimens of L. paraclaparedianus or even some other, still undescribed, species. The following characteristics were not mentioned in the original description of L. claparedianus: First, the prostomium is conical with a pointed tip in L. paraclaparedianus, while the prostomium is rounded in our specimens of L. claparedianus. Second, the upper tooth of the anterior ventral chaetae is slightly longer and thinner than the lower in L. paraclaparedianus, but clearly longer than, and about as thick as or thicker than the lower in L. claparedianus (e.g., Kennedy 1969; Brinkhurst 1971). Third, there is a distinct constriction in the outer end of the penis sheath of the former (Fig. 5C,D; see also Liu et al. 2017a, fig. 3), while the sheath tapers off slowly in the latter (Fig. 8C,D). As discussed in Remarks for L. paraclaparedianus above, and shown also by Liu et al. (2017a, Table 1), the penis sheaths of L. claparedianus and L. paraclaparedianus are similar, both in size and proportions; the most clearcut difference is the size of the upper teeth in chaetae of anterior segments (comp. Figs. 5A,B, 8A,B). Limnodrilus claparedianus has a worldwide distribution, but in China it does not appear to be as common as L. paraclaparedianus. We only collected the species in Shanxi, Jiangsu and Heilongjiang, Liu et al. (2017a) reported it from the Province Shanxi too (Hanjiang River)., Published as part of Zhou, Tingting, Peng, Yu, Wang, Hongzhu, Ers��us, Christer & Cui, Yongde, 2021, Molecular taxonomy and description of a new species of Limnodrilus (Naididae, Clitellata, Annelida) in China, pp. 301-321 in Zootaxa 5082 (4) on pages 316-318, DOI: 10.11646/zootaxa.5082.4.1, http://zenodo.org/record/5792737, {"references":["Ratzel, V. F. (1868) Beitrage zur anatomischen und systematischen Kenntniss der Oligochaeten. Zeitschrift fur wissenschaftliche Zoologie, 18, 563 - 591, pl. 42.","Liu, Y. K., Fend, S. V. Martinsson, S. & Erseus, C. (2017 a) Extensive cryptic diversity in the cosmopolitan sludge worm Limnodrilus hoffmeisteri (Clitellata, Naididae). Organisms Diversity & Evolution, 17, 477 - 495. https: // doi. org / 10.1007 / s 13127 - 016 - 0317 - z","Bretscher, K. (1896) Die Oligochaeten von Zurich in systematischer und biologischer Hinsicht. Revue Suisse De Zoologie, 35, 499 - 532. https: // doi. org / 10.5962 / bhl. part. 117941","Brinkhurst, R. O. (1971) Family Tubificidae. In: Brinkhurst, R. O. & Jamieson, B. G. M. (Eds.), Aquatic Oligochaeta of the World. Oliver & Boyd, Edinburgh, pp. 444 - 625.","Brinkhurst, R. O. (1965) Studies on the North American aquatic Oligochaeta II: Tubificidae. Proceedings of The Academy of Natural Sciences of Philadelphia, 117 (4), 117 - 172.","Chen, Y. (1940) Taxonomy and faunal relations of the limnitic Oligochaeta of China. Contributions from the Biological Laboratory of the Science Society of China, Zoological Series, 14, 1 - 132.","Kennedy, C. R. (1969) The variability of some characters used for species recognition in the genus Limnodrilus Claparede (Oligochaeta: Tubificidae), Journal of Natural History, 3: 1, 53 - 60. https: // doi. org / 10.1080 / 00222936900770061"]}

Genus Bratislavia Ko��el, 1976 Type species. Bratislavia palmeni (Munsterhjelm, 1905). Diagnosis. See Ko��el (1976) and Harman & Loden (1978)., Published as part of Gusakov, Vladimir A., 2021, A new naidid oligochaete species (Annelida, Clitellata, Naididae) from Vietnam with asexual reproduction by fragmentation, pp. 357-372 in Zootaxa 5082 (4) on page 359, DOI: 10.11646/zootaxa.5082.4.4, http://zenodo.org/record/5792809, {"references":["Kosel, V. (1976) Bratislavia gen. nov. a new genus for Pristina elegans Finogenova, 1966 (Oligochaeta: Naididae). Biologia, Bratislava, 31, 105 - 108.","Harman, W. J. & Loden, M. S. (1978) Bratislavia unidentata (Harman, 1974) (Oligochaeta: Naididae), a redescription. Southwestern Naturalist, 23 (4), 541 - 544. https: // doi. org / 10.2307 / 3671176"]}

The freshwater annelid worm genus Limnodrilus, including the widely distributed L. claparedianus Ratzel, 1868, is common in Chinese freshwater ecosystems. One species, previously recognized as morphologically intermediate between L. claparedianus and the North American taxon L. cervix Brinkhurst, 1963, is here described as a new species, L. paraclaparedianus Zhou & Cui n. sp., using both molecular and traditional taxonomy. Comparisons of sequences of the Cytochrome Oxidase subunit I (COI) mtDNA in a sample of Limnodrilus species showed that the distances between species were generally higher than the divergences within them. Phylogenetic analysis of COI as well as 16S mtDNA and Internal Transcribed Spacer 2 (ITS2) nDNA confirmed that the new species is an independent lineage. Moreover, morphological differences in the prostomium, characteristics of the chaetae and internal genitalia support the separation of the species.

Bratislavia gusevi sp. n. (Figures 2���4; Table 1; Appendix) Pristina sp. No 2. Gusakov et al. 2014: 170, 176; Figs 3.2.1а, б. Holotype. Complete specimen, sexually immature; deposited in the collection of the Zoological Institute of the Russian Academy of Sciences, St. Petersburg, slide inventory number 1/48237. Paratypes. Two complete immature individuals and nine fragments; deposited in the Laboratory of Ecology of Aquatic Invertebrates of the Papanin Institute for Biology of Inland Waters Russian Academy of Sciences (Borok, Yaroslavl Province), in the collection of representatives of meiobenthos from water bodies of Vietnam: slides No. 121, 413. Type locality. Vietnam, Đ���ng Nai Province, C��t Ti��n National Park, forest stream B���n C���. Holotype collected on September 8, 2010 (leg. V. A. Gusakov), paratype specimens collected on September 8, 2010, and on June 26, 2019 (leg. V. A. Gusakov and E.S. Gusev). Etymology. The species is named after our friend, colleague and a regular workmate of our expeditions in Vietnam, well-known algologist, Evgeniy S. Gusev, who collected material with the new oligochaete species described here in the B���n C��� stream in 2019. Species diagnosis. Small naidid oligochaetes, body length of fixed specimens 1.6���2.2 mm. Body wall without outer papilla-like or branchial formations. Segment number 23���39 or more. Asexual reproduction by architomy. No eyes, no proboscis, no intestinal dilatation. Coelomocytes present. Dorsal bundles of chaetae from II, with one, rarely two, hair and one, rarely two, simple-pointed or bifid, or trifid needle chaetae. Bifid and trifid needles mostly in anterior segments, simple-pointed chaetae mostly in posterior segments; in IV always peculiar, enlarged simplepointed needle chaetae. Ventral chaetae from II, commonly 3���5 per bundle, bifid. Anterior and subsequent ventral chaetae are similar in shape and size, with upper teeth somewhat longer than the lower in the first 4���7 segments, the teeth approximately equal in length in the 3���5 following segments, and the upper teeth a little shorter than the lower afterwards. Description of the material. Body. Small worms with a weakly transparent body in fixed state. All individuals without sexual organs or budding zones. Complete specimens with 23���34 segments and have a body length 1.6��� 2.2 mm and maximum diameter 186���257 ��m (mostly in IX���XII) (Fig. 2A; Table 1; Appendix). One posteriorly incomplete specimen with 39 segments. Integument slightly wrinkled, with shallow transverse grooves, without papillae-like and/or branchial formations. No eyes. Prostomium conical-rounded, proboscis absent. Body ends with a short pygidium (Fig. 2A, E). No intestinal dilatation. Coelomocytes present, most numerous in the mid-body (Fig. 2C). Body surface of one worm with randomly attached grains of sand and detritus, in the rest of specimens, the integument is practically clean. No indications of tubes created from secreted mucus and foreign matter detected. Incomplete individuals. All incomplete body ends (anteriorly and/or posteriorly) intact and complete. Segment number 12���39, body length 0.8���3.2 mm, diameter 135���262 ��m (Fig. 2F; Fig. 3A; Table 1;). Three types of incomplete individuals were detected: (1) head complete, posterior end incomplete, (2) head incomplete, posterior end complete, (3) both head and posterior end incomplete (see Appendix); in the following referred to as "anterior", "posterior", and "mid-body" fragments, respectively. One anterior fragment with inchoate pygidium, while in four others, the body abruptly ends on one of the segments (Fig. 2F; Appendix). Two posterior fragments with an abruptly terminating anterior end, head segments plus prostomium missing, and with a complete posterior end, including pygidium. One of the latter with a constriction at the end of the first third of the body (between VIII and IX counting from the anterior-most segment), probably an incipient fission zone. Another posterior fragment with partially broken body between XIII and XIV, apparently in the process of fission (Fig. 3A, C, D; Appendix). Both mid-body fragments with incipient pygidium and partially regenerated anterior body ends: prostomium and mouth distinguishable (Fig. 3B; Appendix). Dorsal chaetae. Dorsal bundles from II (Fig. 2D; Appendix) with five types of the chaetae: hairs, regular simple-pointed needles, enlarged simple-pointed needles, bifid needles, and trifid needles (Figs. 3A, B, 4A���E). Bifid and trifid needles mostly in anterior segments, being gradually replaced by single-pointed needles in posterior segments, with variations among specimens (see Appendix and further description for more details). Hair chaetae mostly finely pilose (predominantly in the proximal half) (DIC-contrast, x900���1500 magnification), some apparently smooth. One hair per bundle; in anterior segments sometimes two. Hairs often absent especially in one to three posterior segments. In bundles with two hairs, one clearly shorter and thinner than the other, most likely a growing replacement hair. At times, only a short hair present in a bundle (see Appendix). Length and diameter (proximally) of long hairs 103���291 ��m and 1.1���2.5 ��m, respectively, short hairs 51���88 ��m long and 0.5���1.2 ��m wide (Table 1). The longest hair chaetae usually in IV���X, except for some regenerating specimens with incomplete heads, here longest hairs in the most anterior segments. The regular simple-pointed needles without nodulus, slightly sickle-like curved in the dorsal third to half, with a pointed tip, distinctly rounded at the end (Fig. 4A, C); 47���72 ��m long and 1.6���2.7 ��m wide (Table 1). Longest regular needles usually in mid-body segments, more anteriorly in some specimens with incomplete head. Generally, one regular needle per bundle, very rarely together with a bifid needle (2 specimens, see Appendix). Two specimens with segments that have a regular needle on one side and a bifid needle on the other. Regular simple-pointed needles usually from VII���XIII, in some fragments as early as from III. Within the first 7���17 segments (rarely also in the posterior half of the body), the regular needle chaetae usually alternating with bifid or trifid ones, for variations from this pattern see Appendix. Enlarged needle chaetae similar in shape to regular needles, but about 1.1���1.3 times as long (62���75 ��m) and 1.5���2.0 times as thick (3.1���4.4 ��m) (Table 1; Fig. 4A, B). In individuals with a complete head, enlarged needles normally present in segment IV, one, rarely two per bundle (see Appendix; Fig. 2D). One posterior fragment has enlarged needles in the very first segment; one mid-body fragment has them in the second segment (Fig. 3A, B). Enlarged needles absent in three further incomplete specimens (see Appendix). Bifid and trifid needle chaetae of same size and shape, except for the intermediate tooth in the latter, slightly curved in the distal 1/4 to 1/3, without nodulus, 29���52 ��m long, 1.3���2.1 ��m wide; the smallest in segments II���III. Teeth short, slightly diverging, upper tooth usually somewhat longer (0.90���1.86 ��m) than the lower (0.85���1.72 ��m), occasionally teeth equal in length (Fig. 4A, D, E; Table 1). Usually one bifid or trifid needle per bundle, for variations see Appendix. Bifid and trifid needle chaetae mainly in the anterior part of the body, within the first 7���17 segments, excluding IV, which normally bears enlarged simple-pointed needles. In single cases bifid needles in more posterior bundles. Trifid needles less common than bifid needles, absent in anterior segments. As previously noted, bifid and trifid needles may alternate with the regular simple-pointed needles in different segments. In some individuals bifid and/or trifid needles absent. In individuals with incomplete head, any type of needle chaetae may be absent in the first one to three segments (see Appendix). Ventral chaetae. Ventral chaetae from II, in the recently detached fragments without a head part, sometimes directly in I. As a rule, 3���5 per bundle, 4���5 in anterior body half, 3���4 in the posterior half. Some posterior segments with only 1���2 chaetae per bundle, rarely 1���2 chaetae per bundle also in other body regions (see Appendix). Anterior and subsequent ventral chaetae alike, bifid, moderately s-shaped, more curved towards the posterior end of the body, 47���72 ��m in length and 1.8���3.1 ��m in width, with a feebly marked, slightly distal (anteriorly) or slightly proximal (posteriorly) nodulus (Fig. 4F���H; Table 1). In complete specimens, longest chaetae usually in IV���IX and further, excluding the hindmost segments. Upper teeth always slightly thinner than lower, longer than lower in the first 4���7 segments, as long as lower in 3���5 subsequent segments, slightly shorter than lower following segments (see Fig. 4F���H). In some individuals with incomplete front part of the body, chaetae with equal teeth present from the very first segments. Distribution. To date the species has not been found outside of the type locality., Published as part of Gusakov, Vladimir A., 2021, A new naidid oligochaete species (Annelida, Clitellata, Naididae) from Vietnam with asexual reproduction by fragmentation, pp. 357-372 in Zootaxa 5082 (4) on pages 359-364, DOI: 10.11646/zootaxa.5082.4.4, http://zenodo.org/record/5792809, {"references":["Gusakov, V. A., Gagarin, V. G. & Semenova, L. M. (2014) Taxonomic composition and structure of meio- and macrozoobenthos of the investigated water bodies. In: Pavlov, D. S. & Zworykin, D. D. (Eds.), Ecology of inland waters of Vietnam. KMK Scientific Press Ltd., Moscow, pp. 163 - 190. [in Russian]"]}

The main objective of this study is to present a new record of Tasserkidrilus cf. americanus found in a channel near the Tešmak swamp in Slovakia (Central Europe) and to compare its morphological features and habitat requirements with those of populations occurring in North America and Europe. The new specimens are similar to those found in The Netherlands and Belgium, but dissimilar to previously reported North American material of T. americanus, reopening the question of whether the European form is a separate species. The European form has the penis sheaths approximately twice as long as and wider than the North American form and may inhabit slow-flowing or standing waters of a eutrophic character, which is in conflict with the current knowledge on the morphology and ecology of North American populations. Further investigation is necessary to solve the questions about the origin and taxonomic relationship of the European population to other populations.