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NEOECHINISCOIDES ASKI MØBJERG, JØRGENSEN & KRISTENSEN SP. NOV. Diagnosis: Interstitial, medium-sized Neoechiniscoides with six to nine claws on each leg and 8,8,8,7 as the most common claw formula. Large black to dark brown eyes. Dorsal cuticle with star-like, polygonal structures arranged in transverse rows that continue ventrally on the head. Abdomen with a smooth cuticle, but polygonal structures are present on lateral anal lobes.The mouth is subterminaland lacksdorsalmouthplates; instead, three circular structures are present surrounding the mouth opening. The stylets and buccal tube are relatively short. Stylet supports are not observed using light microscopy. Calcium carbonate incrustations are found only in the anterior part of the pharyngeal placoids. Cirrus Aand E have a single spiral sculpture at the basis. Internal and external cirri have swollen bases. Spine-shaped setae are present on leg III. Legs Iand II have small domeshaped sensory organs, and leg IV has a papilla similar to the primary clava. Females have a flat and males a more raised, nearly papillary secondary clava. The male gonopore is a five-lobed, nearly penis-like structure (not ovoid). The female gonopore is a six-lobed rosette located on a ring-shaped protrusion. Asmall ventral plate is present in front of the female gonopore, and two small depressions (interpreted as muscle attachment sites) are present lateral to the female gonopore. Males lack this ventral plate; the muscle attachments are present, but placed more anteriorly with respect to the male gonopore. Both sexes have enlarged lateral anal lobes (neochiniscoidid anal system). Etymology: Named for Ask Møbjerg Jørgensen, who in turn is named for the Nordic mythological ‘Tree of Life’, Ask Yggdrasil. Holotype (Figs 2D, F, 4; Table 1): Female, 301 µm long, with mature ovary (three oocytes) and welldeveloped six-lobed gonopore. The animal is in moult. Deposited at The Natural History Museum of Denmark (NHMD-230293). Type locality: Collected 17 July 2013 in the L’Aber de Roscoff, Brittany, France (48°43′17.251″N, 04°00′26.522″W) by Nadja Møbjergand Aslak Jørgensen. Collected from oxic, sandy sediment with few stones. Allotypic paratype (Figs 2E, 5; Table 1 ): Male, 228 µm long, with large secondary clavae, mature spermatozoa in the seminal vesicles and well-developed papillary gonopore. Deposited at The Natural History Museum of Denmark (NHMD-230297). Collected 6 July 2012 in the L’Aber de Roscoff, Brittany, France (48°43′17.251″N, 04°00′26.522″W) by Nadja Møbjerg and Aslak Jørgensen. Collected from oxic, sandy sediment with few stones. Other paratypes (Figs 2C, 2G, 2H, 3; Table 1): In total, 14 additional paratypes were collected at the same locality as the holotype and allotype in the periodfrom 6 July 2012 to 17 July 2013. Seven specimens (six females and one male) were mounted on microslides in glycerol and sealed with Glyceel (NHMD-230294 to 230302). Seven paratypes (four females and three males) were mounted on three SEM-stubs (NHMD-230303 to 230305) and used for scanning electron microscopy. All specimens were deposited at The Natural History Museum of Denmark. Additionally, digital images of four voucher specimens that have been used for molecular work exist (Fig. 2B; see Møbjerg et al., 2016: Echiniscoides sp. B / T 16, GenBank accession numbers KX 363644 and KX 363655; Echiniscoides sp. B/T18, GenBank accession numbers KX363645 and KX363656; Echiniscoides sp. B/T20, GenBank accession number KX363657; and Echiniscoides sp. B/ T21, GenBank accession number KX363658). Description (Figs 2–6; Table 1): The collected specimens have a measured body length ranging from 207 (smallest males) to 301 µm (holotypic female). The most common claw formula of N. aski seems to be 8,8,8,7, but the number of claws varies significantly between and within specimens, as illustrated by the holotype, which has a different number of claws on the left (8,9,8,7) and the right sides (8,8,8,8), respectively (Table 1). The dorsal cuticle is characterized by a polygonal granulation that continues ventrally on the head. The polygons are between 2 and 5 µm in size, with the size of the granulation decreasing laterally and in depressions of the cuticle. Each polygon has several fibres that connect to neighbouring polygons. The dorsal cuticle is modified in connection with muscle attachment sites (Figs 3F, 5). Specifically, five dorsal cuticular attachment sites (without polygon structure) were observed on the caudal segment. The buccopharyngeal tube is relatively short, and the buccopharyngeal apparatus appears similar to that of Echiniscoides sigismundi sigismundi (M. Schultze, 1865). The sensory structures are also of E. s. sigismundi type: black to dark brown eyes, two small domes (p1 and p2) on leg Iand II, respectively, and p3 is a seta. The sensory structure on leg IV is similar to the primary clava; both are a papillary structure with a tiny spine. Cirri Aand Eare short, with a few spiral striations at the base. The secondary clava appear different in males compared with females. In females, they seem flatter and are surrounded by a ring of unsculptured cuticle (Figs 3C, 4), whereas the male has a slightly more protruding secondary clava that can be seen from the dorsal side (Figs 3H, 5). In both sexes, the secondary clava attach directly on the head (not as a projection as in E. s. sigismundi). The gonopore of the female is unique within the Echiniscoididae and is formed of six large units positioned on a ring-shaped cuticular protrusion. Two small depressions (Figs 3B, 4) are situated close to the gonopore; we interpret these as muscle attachment sites. Asmall cuticular plate is present in front of the gonopore (Figs 3B, 4); males lack this structure. The anal system consists of three lobes: two lateral and a terminal lobe. The anus appears as an opening at the junction between the three lobes. The lateral lobes of the anal systems appear as a double structure, with two wings (Figs 2A, F, 3B, G, 4, 5, 6). We have no transmission electron microscopy of these lobes, but hypothesize that they might be glandular.

FAMILY ECHINISCOIDIDAE KRISTENSEN & HALLAS, 1980 Diagnosis (amended): Unplated, marine Echiniscoidea. Adults with supernumerary claws (six to 13) on each leg. Secondary clava (papilla cephalica) domeshapedor almostflat (indistinct). Median cephalic cirrus always absent. Other cephalic appendages and leg appendages small (reduced). Cirri Aand E similar in both structure and length. The fourth leg sensory structure is papillar, as is the primary clava. Stylet sheath present; stylet supports always absent. Seminal receptacles lacking. External fertilization of the smooth eggs. Anal system consists of two lateral lobes and a terminal lobe. The anal opening is located in front of the terminal lobe. Type genus: Echiniscoides Plate, 1889. Discussion: The family Echiniscoididae consists of two subfamilies: Echiniscoidinae and Isoechiniscoidinae. The presence of supernumerary (six to 13) claws in adults is not seen in any other heterotardigrades. Seminal receptacles are never present in Echiniscoididae, but within Echiniscoidea seminal receptacles are found in Oreella Murray, 1910 (Binda & Kristensen, 1986; Dastych et al., 1998)., Published as part of M��bjerg, Nadja, J��rgensen, Aslak & Kristensen, Reinhardt M., 2020, Ongoing revision of Echiniscoididae (Heterotardigrada: Echiniscoidea), with the description of a new interstitial species and genus with unique anal structures, pp. 663-680 in Zoological Journal of the Linnean Society 188 (3) on page 668, DOI: 10.1093/zoolinnean/zlz122, http://zenodo.org/record/4623663, {"references":["Kristensen RM, Hallas TE. 1980. The tidal genus Echiniscoides and its variability, with erection of Echiniscoididae fam. n. (Tardigrada). Zoologica Scripta 9: 113 - 127.","Binda MG, Kristensen RM. 1986. Notes on the genus Oreella (Oreellidae) and the systematic position of Carphania fluviatilis Binda, 1978 (Carphanidae fam. nov., Heterotardigrada). Animalia 13: 9 - 20.","Dastych H, McInnes SJ, Claxton SK. 1998. Oreella mollis Murray, 1910 (Tardigrada): a redescription and revision of Oreella. Mitteilungen aus dem Hamburgischen Zoologische Museum und Institut 95: 89 - 113."]}

SUBFAMILY ECHINISCOIDINAE M��BJERG, KRISTENSEN & J��RGENSEN, 2016 Diagnosis (amended): Unplated, marine Echiniscoidea. Adults with supernumerary anisonych claws on each leg. Secondary clava (papilla cephalica) dome shaped or almost flat (indistinct). Other cephalic appendages and leg appendages small (reduced). Cirri Aand Esimilar in both structure and length. First leg sensory structure absent or small and dome shaped; a seta may be present on the second leg. The third leg sensory structure is a pointed papilla or seta. The fourth leg sensory structure is papillar, as is the primary clava. Epicuticular pillars are absent. Seminal receptacles are lacking. Fertilization of eggs is external. The anal system is relatively large and can be seen from the dorsal side as two large, nearly terminal lateral lobes. The terminal anal lobe is relatively small., Published as part of M��bjerg, Nadja, J��rgensen, Aslak & Kristensen, Reinhardt M., 2020, Ongoing revision of Echiniscoididae (Heterotardigrada: Echiniscoidea), with the description of a new interstitial species and genus with unique anal structures, pp. 663-680 in Zoological Journal of the Linnean Society 188 (3) on page 668, DOI: 10.1093/zoolinnean/zlz122, http://zenodo.org/record/4623663, {"references":["Mobjerg N, Kristensen RM, Jorgensen A. 2016. Data from new taxa infer Isoechiniscoides gen. nov. and increase the phylogenetic and evolutionary understanding of echiniscoidid tardigrades (Echiniscoidea: Tardigrada). Zoological Journal of the Linnean Society 178: 804 - 814."]}

1.3 CORONARCTIDAE Renaud-Mornant, 1974 (emended by Hansen 2007) Arthrotardigrades with cylindrical worm-like body. Trunk cuticle smooth, with folds, bearing three somatic cirri (B, C and E) or only one (E). Eleven cephalic sense organs present, including large flattened secondary clavae (occasionally occurring as indistinct areas). Three or four claws, connected to foot by membranes. 1.3.1 Coronarctus Renaud-Mornant, 1974 (emended by Hansen 2007; Figs 4 B, 10A, B) Coronarctidae with unplated cylindrical body, with more or less pronounced cuticular folds. Three pairs of somatic cirri with accordion-like scapus. Conical head separated into two parts; anterior triangular part with median cirrus and flattened secondary clavae, posterior part narrower, bearing lateral cirri and primary clavae. Four claws on each leg displaying more or less important heterometry6. Buccal apparatus without stylet supports or placoids17. Digestive tract with poorly developed diverticula. Female with two seminal receptacles. Type species: Coronarctus tenellus Renaud-Mornant, 1974 Selected literature for further information: Renaud-Mornant (1974, 1987b) and Romano III et al. (2011). 1.3.2 Trogloarctus Villora-Moreno, 1996 (Figs 4 C, 10C) Coronarctidae with elongated body with cuticular folds. Only one pair of somatic cirri (cirrus E) with accordion-like scapus. Eleven cephalic sense organs. Primary clava, small and globular, inserted separately from cirrus A. Secondary clavae flattened and not pronounced. Small cephalic cirri consisting of two parts: scapus and flagellum. External cirri equally distant from the internal cirri and the primary clavae. Spines on all legs. Three claws on each leg, very long on fourth leg. Buccal apparatus with bar-shaped placoids, but without stylet supports. Type species Trogloarctus trionyches Villora-Moreno, 1996 Selected literature for further information: Villora-Moreno (1996)., Published as part of Fontoura, Paulo, Bartels, Paul J., J��rgensen, Aslak, Kristensen, Reinhardt M��bjerg & Hansen, Jesper Guldberg, 2017, A dichotomous key to the genera of the Marine Heterotardigrades (Tardigrada), pp. 1-45 in Zootaxa 4294 (1) on page 26, DOI: 10.11646/zootaxa.4294.1.1, http://zenodo.org/record/831540, {"references":["Renaud-Mornant, J. (1974) Une nouvelle famille de Tardigrades marins abyssaux: Coronarctidae fam. nov. (Heterotardigrada). Comptes Rendus de l'Academie des sciences, Serie D, 278, 3087 - 3090.","Hansen, J. G. (2007) The deep-sea elements of the Faroe Bank tardigrade fauna with a description of two new species. Journal of Limnology, 66 (Supplement 1), 12 - 20.","Renaud-Mornant, J. (1987 b) Bathyal and abyssal Coronarctidae (Tardigrada), description of new species and phylogenetical significance. In: Bertolani, R. (Ed.), Biology of Tardigrades. Selected Symposia and Monographs U. Z. I. 1. Mucchi Editore, Modena, pp. 229 - 252.","Romano III, F., Gallo, M., D'Addabbo, R., Accogli, G., Bagueley, J. & Montagna, P. (2011) Deep-sea tardigrades in the northern Gulf of Mexico with a description of a new species of Coronarctidae (Tardigrada: Arthrotardigrada), Coronarctus mexicus. Journal of Zoological Systematics and Evolutionary Research, 49 (Supplement 1), 48 - 52. https: // doi. org / 10.1111 / j. 1439 - 0469.2010.00597. x","Villora-Moreno, S. (1996) A new genus and species of deep-sea family Coronarctidae (Tardigrada) from a submarine cave with a deep-sea like condition. Sarsia, 81, 275 - 283."]}

1.7 STYGARCTIDAE Schulz, 1951 (emended by Hansen et al. 2012) Arthrotardigrada with dorsal cuticle forming five dorsal plates (one cephalic plate; three body plates ��� segmental plates I, II and III ��� and one caudal plate ��� segmental plate IV). Dorsal plates sometimes absent. Intersegmental dorsal plates and ventral plates may be present. Head subdivided into lobes; complete set of cephalic cirri and two pairs of clavae. Stylet supports always absent. Legs non-digitate with four, three or two claws. Claws with or without dorsal spurs or long dorsal filaments34; claws attached with dorsal basal membrane. Leg sense organs present only on the fourth pair of legs, as bulb-shaped papillae. Seminal receptacles formed as cuticular pouches with short straight ducts or with long sinuous ducts close to the female gonopore. Selected literature for further information: A key to the Stygarctidae can be found in Morone De Lucia et al. (1984)., Published as part of Fontoura, Paulo, Bartels, Paul J., J��rgensen, Aslak, Kristensen, Reinhardt M��bjerg & Hansen, Jesper Guldberg, 2017, A dichotomous key to the genera of the Marine Heterotardigrades (Tardigrada), pp. 1-45 in Zootaxa 4294 (1) on page 32, DOI: 10.11646/zootaxa.4294.1.1, http://zenodo.org/record/831540, {"references":["Schulz, E. (1951) Uber Stygarctus bradypus n. g., s. p., einen Tardigraden aus dem Kustengrundwasser und seine phylogenetische Bedeutung. Kieler Meeresforschung, 8, 86 - 97.","Hansen, J. G., Kristensen R. M. & Jorgensen, A. (2012) The armoured marine tardigrades (Arthrotardigrada, Tardigrada). Scientia Danica, Series B. Biologica, 2, 1 - 91."]}

1. ARTHROTARDIGRADA Marcus, 1927 Median cephalic cirrus usually present, rarely absent. Digitate legs with or without claws or non-digitate legs with claws always implanted directly into the legs. Selected literature for further information: An early treatment of the arthrotardigrades can be found in Renaud- Mornant (1982a). Early general keys to marine arthrotardigrades can be found in Pollock (1976) for the northeastern USA, Ramazzotti & Maucci (1983) for all known species at the time of publication, and Morgan & O���Reilly (1988) for Scottish species., Published as part of Fontoura, Paulo, Bartels, Paul J., J��rgensen, Aslak, Kristensen, Reinhardt M��bjerg & Hansen, Jesper Guldberg, 2017, A dichotomous key to the genera of the Marine Heterotardigrades (Tardigrada), pp. 1-45 in Zootaxa 4294 (1) on page 25, DOI: 10.11646/zootaxa.4294.1.1, http://zenodo.org/record/831540, {"references":["Marcus, E. (1927) Zur Anatomie und Okologie mariner Tardigraden. Zoologische Jahrbucher Abteilung fur Systematik, Okologie und Geographie der Tiere, 53, 487 - 558.","Renaud-Mornant, J. (1982 a) Species diversity in marine Tardigrada. In: Nelson, D. (Ed.), Proceedings of the Third International Symposium on Tardigrada. East Tennessee State University Press, Johnson City, Tennessee, 149 - 177.","Pollock, L. W. (1976) Marine flora and fauna of the northeastern United States. Tardigrada. National Oceanic and Atmospheric Administration Technical Report, National Marine Fisheries Service, Circular 394, 1 - 25.","Ramazzotti, G. & Maucci, W. (1983) Il Phylum Tardigrada - III edizione. Memorie dell'Istituto Italiano di Idrobiologia, 41, 1 - 1012.","Morgan, C. I., & O'Reilly, M. (1988) Additions to the Scottish tardigrade fauna, including a description of Megastygarctides setoloso new species, with a revised key for identification of Scottish marine species. Glasgow Naturalist, 21, 445 - 454."]}

1.6 RENAUDARCTIDAE Kristensen & Higgins, 1984 (emended by Hansen et al. 2012) Arthrotardigrades with segmental dorsal and ventral plates, both claws and toes present. Four toes are accompanied by four accessory claw spines19 on each foot in the adults. Primary and secondary clavae, and a complete set of cephalic cirri present. 1.6.1 Renaudarctu s Kristensen & Higgins, 1984 (emended by Hansen et al. 2012) (Figs 5 A, 11C) Renaudarctidae with segmental dorsal plates, two dorsal intersegmental plates, four dorsal intersegmental ridges33, a dorsal plate on each leg, and thin ventral plates. Each body plate with a pair of lateral spines. Caudal 32. In the terminology of this key ���dorsal bristle��� = accessory point. 33. According to Hansen et al. (2012), these intersegmental ridges are prominent cuticular structures forming a ridge rather than a true plate, present between segmental and intersegmental plates. plate with two pairs of lateral spikes, one pair of caudal spikes, and lateral margins continuous with furca-like caudal extensions. Complete set of cephalic sense organs. Leg IV with small ovoid papilla; all other legs lack sensory structures. Cirrus E with cirrophore. Female and male with ovoid gonopore papillae adjacent to terminal anal system. Female with latero-ventral projections containing seminal receptacles. Type species: Renaudarctus psammocryptus Kristensen & Higgins, 1984 Remark: During the publication process of this paper a new genus and species, Nodarctus hallucis Fujimoto &Yamasaki, 2017, of Renaudarctidae have been described and, consequently, the diagnosis of the family has been emended. The genus Nodarctus can be easily distinguished from Renaudarctus in having leg IV with two digits, subdivided dorsal body plates without lateral processes, and a large single caudal spike (see Fujimoto & Yamasaki 2017)., Published as part of Fontoura, Paulo, Bartels, Paul J., J��rgensen, Aslak, Kristensen, Reinhardt M��bjerg & Hansen, Jesper Guldberg, 2017, A dichotomous key to the genera of the Marine Heterotardigrades (Tardigrada), pp. 1-45 in Zootaxa 4294 (1) on pages 31-32, DOI: 10.11646/zootaxa.4294.1.1, http://zenodo.org/record/831540, {"references":["Hansen, J. G., Kristensen R. M. & Jorgensen, A. (2012) The armoured marine tardigrades (Arthrotardigrada, Tardigrada). Scientia Danica, Series B. Biologica, 2, 1 - 91.","Fujimoto, S. & Yamasaki, H. (2017) A new genus and species of Renaudarctidae (Heterotardigrada: Arthrotardigrada) from Ryukyu Archipelago, Japan, Marine Biology Research, 1 - 2. [published online]"]}

1.2 BATILLIPEDIDAE Ramazzotti, 1962 (emended by Gallo d���Addabbo et al. 2005) Arthrotardigrada with a trapezoid head divided into three parts: two lateroventral triangular lobes bearing all the cephalic cirri (except the medial cirrus) along with the primary and secondary clavae, and a central lobate portion with the medial cirrus. 15. In the terminology of this key ���internal accessory point��� = secondary point. Simple cephalic cirri with lance-like or frayed tips. Tubular primary clavae with or without one or more constrictions; papillar secondary clavae, not always evident. Lipoid eye spots sometimes present. Stylet supports always present. Lateral intermetamerical processes present or absent. Legs digitate with four or six toes, according to the age, bearing terminal adhesive discs. Claws absent. Sense organs present on all the legs. Cirrus E dorsal to the fourth pair of legs. A longitudinal groove generally present between the rosette-like female gonopore and the anus. Single internal seminal receptacle16 sometimes present, opposite the oviduct. Circular male gonopore covered with a crescent fold. Caudal apparatus present or absent. Cuticular punctations, consisting of pillars in the epicuticle, always present. Dorsal cuticular pillars always higher than the ventral ones. 1.2.1 Batillipes Richters, 1909 (Figs 3 E, 7I, 14G) Generic diagnosis as that of the family. Type species: Batillipes mirus Richters, 1909 Selected literature for further information: Pollock (1970) defined patterns of toe length of Batillipes species, and Pollock (1971) included an early key to this genus. McKirdy (1975) summarized and discussed the taxonomic characters within the genus. Kristensen (1978) introduced new characters for the genus Batillipes using the electron microscope. Rho et al. (1999) provided a more recent key, but only covered Korean species. Kristensen & Mackness (2000) suggested a toe formula for all known species at that time. See also J��rgensen et al. (2014), Menechella et al. (2015), Rubal et al. (2016), and Menechella et al. (2017) for a comprehensive key to all known species., Published as part of Fontoura, Paulo, Bartels, Paul J., J��rgensen, Aslak, Kristensen, Reinhardt M��bjerg & Hansen, Jesper Guldberg, 2017, A dichotomous key to the genera of the Marine Heterotardigrades (Tardigrada), pp. 1-45 in Zootaxa 4294 (1) on pages 25-26, DOI: 10.11646/zootaxa.4294.1.1, http://zenodo.org/record/831540, {"references":["Ramazzotti, G. (1962) Il Phylum Tardigrada. Memorie dell'Istituto Italiano di Idrobiologia, 14, 1 - 595.","Gallo d'Addabbo, M., Sandulli, R. & de Zio Grimaldi, S. (2005) New Batillipedidae (Tardigrada, Heterotardigrada) from the Orosei Gulf, Sardinia, Tyrrhenian Sea. Zoologischer Anzeiger, 243, 219 - 225.","Richters, F. (1909) Tardigraden-Studien. Bericht der Senckenbergzischen Naturforschenden Gesellschaft in Frankfurt am Main, 1 - 2, 28 - 49.","Pollock, L. W. (1970) Batillipes dicrocercus n. sp., Stygarctus granulatus n. sp. and other Tardigrada from Woods Hole, Massachusetts, U. S. A. Transactions of the American Microscopical Society, 89 (1), 38 - 52. https: // doi. org / 10.2307 / 3224613","Pollock, L. W. (1971) On some British marine Tardigrada including two new species of Batillipes. Journal of the Marine Biological Association of the United Kingdom, 51, 93 - 103.","McKirdy, D. J. (1975) Batillipes (Heterotardigrada): Comparison of six species from Florida (USA) and a discussion of taxonomic characters within the genus. Memorie dell'Istituto Italiano di Idrobiologia Pallanza, 32, 177 - 223.","Kristensen, R. M. (1978) Notes on marine heterotardigrades. 1. Description of two new Batillipes species, using the electron microscope. Zoologischer Anzeiger, 200, 1 - 17.","Rho, H. S., Min, B. H. & Chang, C. Y. (1999) Taxonomic study of marine tardigrades from Korea. I Genus Batillipes (Heterotardigrada: Batillipedidae). The Korean Journal of Systematic Zoology, 15 (1), 107 - 118.","Kristensen, R. M. & Mackness, B. S. (2000) First record of the marine tardigrade genus Batillipes (Arthrotardigrada: Batillipedidae) from South Australia with a description of a new species. Records of the South Australian Museum, 33, 73 - 87.","Jorgensen, A., Boesgaard, T. M., Mobjerg, N. & Kristensen, R. M. (2014) The tardigrade fauna of Australian marine caves: With descriptions of nine new species of Arthrotardigrada. Zootaxa, 3802 (4), 401 - 443. https: // doi. org / 10.11646 / zootaxa. 3802.4.1","Menechella, A. G., Bulnes, V. N. & Cazzaniga, N. J. (2015) A new Batillipedidae (Tardigrada. Arthrotardigrada) from Argentina. Zootaxa, 4032 (3), 339 - 344.","Rubal, M., Veiga, P., Fontoura, P. & Sousa-Pinto, I. (2016) A new Batillipes (Tardigrada, Heterotardigrada, Batillipedidae) from North Portugal (Atlantic Ocean). Marine Biodiversity. [published online]","Menechella, A. G., Bulnes, V. N. & Cazzaniga, N. J. (2017) Two new species of Batillipes (Tardigrada, Arthrotardigrada, Batillipedidae) from the Argentinean Atlantic coast, and a key to all known species. Marine Biodiversity, 1 - 9. [published online]"]}

1.4 HALECHINISCIDAE Thulin, 1928 (emended by Fujimoto et al. 2016) Arthrotardigrades without sclerotized dorsal segmental plates. The complete set of cephalic appendages usually consist of unpaired median cirrus, three pairs of cirri and two pairs of clavae, buccal clavae may be 16. A spermatheca according Grimaldi de Zio & D���Addabbo Gallo 1975. 17. Three very large droplet-shaped apophyses flank the buccal tube anterior to the pharyngeal bulb. indistinguishable or consist of fused secondary and tertiary clavae. Unmodified papillate sensory organs on leg IV. Adult legs terminate in either four digits with claws or four suction pads with or without claws. Peduncles present only in external digits, or as tarsal cuticular bars or absent. Single-pointed, crescent shaped claws may bear dorsal spurs and/or minute calcars. Rosette-like female gonopore and paired seminal receptacles. Selected literature for further information: Grimaldi de Zio et al. (1990a), J��rgensen & Kristensen (2001). An early key to the Halechiniscidae can be found in Renaud-Mornant (1984)., Published as part of Fontoura, Paulo, Bartels, Paul J., J��rgensen, Aslak, Kristensen, Reinhardt M��bjerg & Hansen, Jesper Guldberg, 2017, A dichotomous key to the genera of the Marine Heterotardigrades (Tardigrada), pp. 1-45 in Zootaxa 4294 (1) on pages 26-27, DOI: 10.11646/zootaxa.4294.1.1, http://zenodo.org/record/831540, {"references":["Thulin, G. (1928) Uber die Phylogenie und das System der Tardigraden. Hereditas Genetiskt Arkiv, 11, 207 - 266. https: // doi. org / 10.1111 / j. 1601 - 5223.1928. tb 02488. x","Fujimoto, S., Jorgensen, A. & Hansen, J. G. (2016) A molecular approach to arthrotardigrade phylogeny (Heterotardigrada, Tardigrada). Zoologica Scripta. [published online]","Jorgensen, A. & Kristensen, R. M. (2001) A new tanarctid arthrotardigrade with buoyant bodies. Zoologischer Anzeiger, 240, 425 - 439.","Renaud-Mornant, J. (1984) Halechiniscidae (Heterotardigrada) de la campagne Benthedi, canal du Mozambique. Bulletin du Museum National d'Histoire Naturelle (Paris), Series 4 e, 6 e (Section A, n ° 1), 67 - 88."]}

1.8 STYRACONYXIDAE Kristensen & Renaud-Mornant, 1983 (emended by Fujimoto et al. 2016) Considered as subfamily Styraconyxinae assigned to the family Halechiniscidae by Kristensen & Renaud-Mornant (1983). Elevated to family level by Fujimoto et al. (2016) as previously suggested by Jørgensen et al. (2010). Arthrotardigrada without sclerotized cuticular plates. Cephalic appendages usually consist of unpaired median cirrus, three pairs of cirri and two pairs of clavae. Buccal clavae may be indistinguishable or third pair of clavae may be present (Angursa Pollock, 1979). Unmodified papillate sensory organs on leg IV. Adult legs terminate in four digits, usually with multipointed claws, rarely single-pointed (Lepoarctus Kristensen & Renaud-Mornant, 1983; Pleocola Cantacuzène, 1951). Peduncles present in all digits, in external digits only with heart-shaped pads on internal digits or absent. Rosette-like female gonopore and paired seminal receptacles. Selected literature for further information: Jørgensen et al. (2014). See Kristensen & Renaud-Mornant (1983) and Kristensen & Higgins (1984a) for keys to this family. 1.8.1 Angursa Pollock, 1979 (emended by Bussau, 1992; Figs 8 I, 12C) Styraconyxidae with four digits. External digits supported by peduncles, internal digits with proximal pads. Claws with two divergent points (hooks), primary hook stronger than secondary hook. Claws retractable into membranous sheath. Dorsal cuticular plates absent. Complete set of cephalic cirri present, sometimes median cirrus may be reduced or absent. Configuration of primary clavae and lateral cirri variable, arising from distinct lateral extension or directly from head. Secondary clavae occasionally present, occurring as indistinct dome-shaped areas. Sometimes tertiary clavae with appearance similar to those of secondary clavae present, situated ventrally to the secondary clavae. Spines present on legs I, II, III or only on legs I. Usually clavoid papillae, mostly with spine, on legs IV. Body smooth and slender. Type species: Angursa bicuspis Pollock, 1979 Selected literature for further information: See Renaud-Mornant (1981b); Bussau (1992) and Villora-Moreno (1998) for keys to this genus. 1.8.2 Bathyechiniscus Steiner, 1926 (emended by Pollock 1983; Fig. 8 B, no drawing of claws) Cylindrical Styraconyxidae with four fully developed toes, each bearing claws with three or more vertically arrayed exposed points, on medial digits at least. Well-developed cephalic cirri present, including median cirrus. Single pair of clavae immediately adjacent to lateral cirri with one or both of these structures arising from a distinct lateral extension of the head, i.e., from a pedestalate base. Spines present on legs I–III and papilla or papilla/spine combination on legs IV. Lateral folds of cuticle or alae absent. Type species: Bathyechiniscus tetronyx Steiner, 1926 Remark: Bathyechiniscus was described by Steiner (1926) as having claws with four points. However, his description was based on only one specimen, and his drawings are rough sketches. Steiner’s Fig. 3 shows four small points, but in his Fig. 5 the fourth point could be interpreted as the posteriormost tip of a crescent-shaped claw (Pollock 1983). The type material for Bathyechiniscus no longer exists, no paper after Steiner ever mentions studying it and no other records of Bathyechiniscus have ever been made. As we cannot determine whether Bathyechiniscus actually has four points or only three, we have not included a drawing for Bathyechiniscus in our illustration of feet (Figs 10–14). 1.8.3 Lepoarctus Kristensen & Renaud-Mornant, 1983 (translated from French; Figs 8 D, 12F) Styraconyxidae with enlarged bell-shaped epicuticle around the body excluding the cephalic region. Complete set of cephalic appendages with cylindrical scapus. Primary clavae retractable into a membranous epicuticular sheath. Secondary clavae indistinct. Cirrus E located in a funnel-shaped epicuticular structure. Spines on legs I; reduced on legs II and vestigial on legs III. Papillae on legs IV with pointed tip. Buccal tube long, stylets and stylet supports very thin, placoids thin. Simple claws retractable into membranous sheath. Type species: Lepoarctus coniferus (Renaud-Mornant, 1975) Selected literature for further information: Kristensen & Renaud-Mornant (1983) transfer Pleocola coniferus Renaud-Mornant, 1975 to Lepoarctus coniferus (Renaud-Mornant, 1975a). 1.8.4 Paratanarctus D’Addabbo Gallo, Grimaldi de Zio, Morone De Lucia & Troccoli, 1992 (Figs 3 C, 9A, 11I) Styraconyxidae with a complete set of cephalic sense organs. Cephalic cirri short and thin; primary clavae tubular. Sense organs of the fourth leg coxal. Cirrus E articulated with an elementary accordion-plated portion. Lance-shaped tarsus with pretarsus. Basal pads on all digits. All claws with external dorsal calcars. Peduncles not present. Type species: Paratanarctus kristenseni D’Addabbo Gallo, Grimaldi de Zio, Morone De Lucia & Troccoli, 1992 Selected literature for further information: D’Addabbo Gallo et al. (1992). 1.8.5 Pleocola Cantacuzène, 1951 (translated from French, following Renaud-Mornant 1979a; Figs 8 C, 12E) Styraconyxidae with strongly convex conical head; Cirri A and clavae implanted in a posterior plan relative to median cirrus. Simple claws. Remark: The original description does not exactly give a diagnosis of the genus: A subsequent incomplete diagnosis has been given by Renaud-Mornant (1979a). Based on the reexamination of Pleocola specimens by Kristensen & Renaud-Mornant (1983) a body smooth and slender; the presence of a complete set of cephalic sense organs; primary clavae short and ovoid; secondary clavae indistinct; spines on legs I, II, III; papillae on legs IV, and cirrus E present are some missing characters characterizing the genus. Type species: Pleocola limnoriae Cantacuzène, 1951. Commensal on the isopod Limnoria lignorum (Rathke, 1799). Selected literature for further information: Kristensen & Renaud-Mornant, 1983. 1.8.6 Raiarctus Renaud-Mornant, 1981 (emended by Jørgensen et al. 2014; Figs 8 G, 12G) Styraconyxidae with the dorso-lateral epicuticular coat supported by long thin pillars 5–6 µm regularly arranged in close parallel lines. With 3-pointed claws42, with or without heart shaped pads on the internal digits. With or without peduncles on every tarsus. Minor primary clava with a cone or tube-like shape; the short, secondary clava either reduced or minor. Body dorso-ventrally flattened. With lateral tube-like openings to the seminal receptacles. Halechiniscid male gonopore (oval papilla with a crescent-shaped opening). Type species: Raiarctus colurus Renaud-Mornant, 1981 Selected literature for further information: see Renaud-Mornant (1981a), D’Addabbo Gallo et al. (1986) and Jørgensen et al. (2014). 1.8.7 Rhomboarctus Renaud-Mornant, 1984 (emended by Hansen et al. 2003a; Figs 8 H, 12D) Styraconyxidae with convex frontal edge; indistinct or lenticular secondary clavae; dorsal cuticle punctated; cuticular fins supported by medium sized pillars, extending on both sides of the body between primary clavae and the fourth pair of legs. More or less evident caudal appendage with cuticular fan with pillars. Peduncles present only on the external digits, proximal pads on the internal ones; all the claws with very thin or vestigial secondary hooks. Type species: Rhomboarctus thomassini Renaud-Mornant, 1984 Remark: Claw bases can appear like a third point. 1.8.8 Styraconyx Thulin, 1942 (emended by Kristensen & Higgins 1984a; Figs 8 A, 12A) Styraconyxidae with four digits. External digits always supported by peduncles; internal digits with proximal pads, peduncles present or absent. Claws with three exposed points (hooks43), may be retracted within claw sheath. Dorsal cuticular plates absent although grid-like pattern of 18–23 folds sometimes present on epicuticle. Complete 42. In the terminology of this key “three points” = primary, secondary and accessory points. 43. In the terminology of this key “three points or hooks” = a primary point and 2 secondary points or an accessory point, primary point and secondary point. set of cephalic cirri always present; configuration of primary clavae and lateral cirri variable, arising from distinct lateral extension or directly from head; secondary clavae occurring as indistinct flat sacs or dome-shaped papillae. Stylet supports, stylets and placoids present. Spines present on legs I–III, clavoid papillae, each with spine, on leg IV. Paired seminal receptacles with ducts opening posterior to the female gonopore present between legs III and IV. Type species: Styraconyx haploceros Thulin, 1942 Selected literature for further information: See Kristensen & Higgins (1984a) and D’Addabbo Gallo et al. (1989) for keys to this genus. See also Chang & Rho (1998) and Bartels et al. (2015) for more recently described species. 1.8.9 Tetrakentron Cuénot, 1892 (emended by van der Land 1975; Figs 8 F, 12H) Styraconyxidae with the body dorsoventrally flattened. Cephalic appendages (including cirrus medianus) very short; only the cephalic papillae are relatively large. Eyes lacking. Mouth opening on buccal cone and anus subterminal. Legs short, with short tibia and digits. Claws compound (with primary and secondary hooks) and with peduncles; those of internal digits with large accessory spine44 on secondary hook; no spurs. Marine, littoral ectoparasitic on burrowing holothurians. Type species: Tetrakentron synaptae Cuénot, 1892 Selected literature for further information: Kristensen (1980). 1.8.10 Tholoarctus Kristensen & Renaud-Mornant, 1983 (emended by Jørgensen et al. 2014; Figs 8 E, 12B) Styraconyxidae with barrell-shaped outer epicuticle surrounding the trunk, the body itself is thin and elongated. Complete set of cephalic appendages. Cone-shaped primary clavae and secondary clavae enlarged surrounding both the internal and external cephalic cirri. Cirri A and E partially surrounded by funnel-shaped epicuticular folds. Leg sense organs always present on the first and fourth pair of legs, though much smaller sense organs may be present on the second and third legs. Flagellum on the sense organ of the first leg always very long. Sense organ on the fourth leg partially enclosed in funnel-shaped epicuticular folds. Females have claws with a main hook, a basal accessory hook and a terminal accessory spur45. Males and larvae migth have simple claws in the external digits. Long buccal tube with two lateral projections at ca. the mid-point. Long and thin stylet supports articulate with the furcae. Placoids consist of a non-calcified cuticular lining, but three small calcified apodemes occur in the anterior part of the pharyngeal bulb. Mouth cone terminal and protruding. Globular coelomocytes seem to be attached to the midgut. Sexual dimorphism in body size and claws. Type species: Tholoarctus natans Kristensen & Renaud-Mornant, 1983

1.1 ARCHECHINISCIDAE Binda, 1978 (following Kristensen & Higgins 1984b) Considered as subfamily Archechiniscinae assigned to the family Halechiniscidae by Grimaldi de Zio & D���Addabbo Gallo (1987). The family Archechiniscidae was reinstated by J��rgensen et al. (2010). Arthrotardigrades with two internal clawed toes having a hook-like dorsal point. Toes with a short basal pad inserted into a tarsal extension. External strong sessile claws with a powerful internal accessory point15. Median cirrus absent or vestigial, cuticle finely pointed, anterior clava and thin dorsal metameric plates also present. 1.1.1 Archechiniscus Schulz, 1953 (following Chang & Rho 1998a) (Figs 4 A, 12I) Archechiniscidae with two external claws directly inserted on the tarsus, and internal claws supported by fingers; median cephalic cirrus very small or absent. Papillate primary clavae and lenticular secondary clavae. Tubular seminal receptacles present. Type species Archechiniscus marci Schulz, 1953 Selected literature for further information: Miller et al. (2012) provides a key to all currently known species of this genus., Published as part of Fontoura, Paulo, Bartels, Paul J., J��rgensen, Aslak, Kristensen, Reinhardt M��bjerg & Hansen, Jesper Guldberg, 2017, A dichotomous key to the genera of the Marine Heterotardigrades (Tardigrada), pp. 1-45 in Zootaxa 4294 (1) on page 25, DOI: 10.11646/zootaxa.4294.1.1, http://zenodo.org/record/831540, {"references":["Binda, M. G. (1978) Risistemazione di alcuni tardigradi con l'istituzione di un nuovo genere di Oreellidae e della nuova famiglia Archechiniscidae. Animalia, 5, 307 - 314.","Kristensen, R. M. & Higgins, R. P. (1984 b) A new family of Arthrotardigrada (Tardigrada: Heterotardigrada) from the Atlantic Coast of Florida, U. S. A. Transactions of the American Microscopical Society, 103 (3), 295 - 311. https: // doi. org / 10.2307 / 3226191","Jorgensen, A., Faurby, S., Hansen, J. G., Mobjerg, N. & Kristensen, R. M. (2010) Molecular phylogeny of Arthrotardigrada. Molecular Phylogenetics and Evolution, 54, 1006 - 1015.","Schulz, E. (1953) Ein neue Tardigraden-Gattung von der pacifischen Kuste. Zoologischer Anzeiger, 151, 306 - 310.","Chang, C. Y. & Rho, H. S. (1998 a) Three new tardigrade species associated with barnacles from the Thai coast of Andaman Sea. The Korean Journal of Biological Sciences, 2, 323 - 331.","Miller, W. R., Clark, T. & Miller, C. (2012) Tardigrades of North America: Archechiniscus biscaynei, nov. sp. (Arthrotardigrada, Archechiniscidae), a marine tardigrade from Biscayne National Park, Florida. Southeastern Naturalist, 11 (2), 279 - 286. https: // doi. org / 10.1656 / 058.011.0209"]}

The three known sympatric Biomphalaria species that occur in Lake Albert; B. choanomphala, B. stanleyi and B. sudanica, were studied using both molecular (COI, 16S and ITS) and shell morphometric data. An unidentified sample of 18 Biomphalaria specimens from Lake Albert were divided in three morphotypes according to aperture height and coiling rate and subsequently identified through molecular inferences and morphometry. The 18 specimens were identified as follows; six specimens were identified as B. sudanica, seven species as B. stanleyi, four as B. cf. choanomphala and a single specimen as B. pfeifferi. The latter was inferred with strong molecular support only, since it had similar shell morphology to typical B. stanleyi snails, thus it might be an ecophenotypic form of B. pfeifferi adapted to a lacustrine environment. Biomphalaria stanleyi exists in forms that resemble B. choanomphala, and B. choanomphala has further overlap in morphology with B. smithi. However, the results showed some disagreement between molecular and morphometric identification, hence making it difficult to rely on shell morphology alone in identification. Overall the morphometric analysis divided Biomphalaria in two possible ecophenotypes i.e. a lacustrine type with rapidly increasing whorls and relatively high apertures and a non-lacustrine type (including snails inhabiting lake edges) with slowly increasing whorls and low apertures.Key words: Biomphalaria, Uganda, Lake Albert, DNA, morphometry.

The freshwater snails belonging to the genus Melanoides Olivier, 1804 are widespread across tropical regions of the world and endemic species have evolved in the African Lakes Malawi, Mweru and Tanganyika. The endemic Melanoides species of Lake Malawi have been investigated several times during the last century, due to their large conchological variation, but no unambiguous answer regarding the number of species has been given. The phylogenetic relationship between morphs or genetic clones of Melanoides in Lake Malawi was inferred by phylogenetic analyses of DNA sequence data from the mitochondrial genes 16S and COI. Additional sequences from GenBank were included to investigate the relationship to other morphs from different parts of the world. For the first time, a putative secondary structure was developed for a partial region of 16S in this genus to identify the variability of the secondary structure in stems and loops. The molecular analyses indicated that several genetic clones exist in Lake Malawi and that M. tuberculata is a paraphyletic taxon. It is not clear from the results whether invasions or dispersals account for the complex situation in Lake Malawi. The basal position of M. admirabilis, endemic to Lake Tanganyika, in the inferred phylogeny indicates that Africa might be the origin of the genus. The results further indicate that three major clades of Melanoides,consisting of several genetic clones, are present in Lake Malawi; one clade consisting of invasive M. tuberculata, another of native M. tuberculata and a third consisting of the M. polymorpha-complex. It appears as if the unique development of morphs within the Melanoides genus in Lake Malawi has evolved primarily by divergence of genetic clones instead of species differentiation.Keywords: Melanoides, Lake Malawi, 16S, COI, phylogenetic relationships

The so-called ‘tun’ state is best known from limno-terrestrial tardigrades and rotifers that rely on this compact\ud body shape for anhydrobiotic survival. Little is known of tun formation in marine species and the evolutionary\ud origin of the state is presently unknown. Here, we investigate desiccation tolerance and tun formation in the\ud marine tidal echiniscoidean tardigrade, Echiniscoides sigismundi (M. Schultze, 1865). Groups of approximately\ud 20 E. sigismundi sampled from Lynæs (Denmark) were dehydrated on filter paper from seawater as well as\ud ultrapurified water and kept for 48 h at 5 °C, after which they were rehydrated in seawater. The activity and\ud behaviour of the tardigrades was examined under a light microscope, whereas scanning electron microscopy was\ud used for high-resolution three-dimensional imaging. When dehydrated from seawater, E. sigismundi enters a tun,\ud however, when exposed to ultrapurified water, the tardigrade swells and becomes incapable of movement, and\ud thus incapable of tun formation. Nonetheless, E. sigismundi tolerates being dehydrated from ultrapurified water,\ud revealing an exceptional and unparalleled resilience towards losing structural integrity. Our results confirm\ud previous investigations, which suggest that tun formation relies on a functional musculature. They further\ud suggest that tun formation may have evolved as a response to elevated external pressure rather than desiccation\ud per se.

GENUS: ISOECHINISCOIDES GEN. NOV. Diagnosis: The same diagnosis as for the subfamily.

Hansen, Jesper Guldberg, Kristensen, Reinhardt Møbjerg, Jørgensen, Aslak, Accogli, Gianluca, D, Rossanna, Addabbo, Gallo, Maria (2016): Postembryonic development, paedomorphosis, secondary sexual dimorphism and population structure of a new Florarctus species (Tardigrada, Heterotardigrada). Zoological Journal of the Linnean Society 178 (4): 871-877, DOI: 10.1111/zoj.12436, URL: http://dx.doi.org/10.1111/zoj.12436

Møbjerg, Nadja, Kristensen, Reinhardt M., Jørgensen, Aslak (2016): Data from new taxa infer Isoechiniscoides gen. nov. and increase the phylogenetic and evolutionary understanding of echiniscoidid tardigrades (Echiniscoidea: Tardigrada). Zoological Journal of the Linnean Society 178 (4): 804-818, DOI: 10.1111/zoj.12500, URL: http://dx.doi.org/10.1111/zoj.12500

SUBFAMILY: ISOECHINISCOIDINAE SUBFAM. NOV. Diagnosis: Predominantly interstitial Echiniscoididae with isonych claws (identical numbers and type of claws on all legs). Epicuticle with pillars. More than four claws (usually six) on each leg in adults. First instar (larvae) with four claws. Sexual dimorphism present. Secondary clavae (cephalic papillae) larger and more dome-shaped in males than in females. Cirri E and cirri A (lateral cirri) very long. Anal system is trilobed with two short lateral lobes and a relatively large terminal lobe. Sensory setae on all four leg pairs. Setae of the first leg pair are very small papillar structures with a tiny spine. Type genus: Isoechiniscoides gen. nov. Type species: Isoechiniscoides sifae gen. nov., sp. nov. Subfamily discussion: At this early stage in the phylogenetic investigation of Echiniscoididae, the morphological characterization of the major clades that are currently inferred by molecular data (see below) is lacking. Here we establish the new subfamily, Isoechiniscoidinae, as its members are clearly distinguishable from the other taxa in Echiniscoididae. The major distinguishing Isoechiniscoidinae characteristics as compared to other echiniscoidids are: isonych claws, epicuticular pillars, longer cirri A and E, and a trilobed anal system. Furthermore, Isoechiniscoidinae was inferred as distinct by the molecular analyses (see below).