On the histological anatomy of Marimermis maritima Rubzov and Platonova, 1974 (Nematoda : Enoplia : Marimermithida), parasite of a sea urchin

#Marimermis maritima Rubzov et Platonova, 1974 a été trouvé pour la première fois depuis sa description originale. Une femelle de plus de 8 cm de longueur, parasitant la cavité générale de #Strongylocentrotus polyacanthus (#Echinoderma : #Echinoidea), a été collectée dans la zone sublittorale supérieure de l'île Ushishir (Iles Kouriles, nord-est du Pacifique). Le spécimen ressemble à un nématode libre, ayant des soies céphaliques et cervicales bien développées. Contrairement à la diagnose originale, #M. maritima possède un canal alimentaire normal, comprenant pharynx muscularisé, intestin pluricellulaire, rectum et anus. Le système génital femelle est pair, replié, avec de nombreux petits oocytes. Dans la région vaginale, la cavité est remplie d'une gangue fibreuse et de différentes cellules, y compris des cellules musculaires. Il n'y a pas de muscles vulvaires spécialisés. Une diagnose amendée des #Marimermithida et une liste des genres sont données. En raison de l'arrangement des sensilles antérieures (6+10), de la position antérieure des ouvertures des débouchés des glandes pharyngiennes, de la lumière triradiée du cardia, le taxon étudié se rapporterait aux #Enoplia$. (Résumé d'auteur

Checklist of the subfamily Adoncholaiminae Gerlach and Riemann, 1974 (Nematoda: Oncholaimida: Oncholaimidae) of the world: genera, species, distribution, and reference list for taxonomists and ecologists

Adoncholaiminae is one of the seven subfamilies in the free-living aquatic nematode family Oncholaimidae. Nematodes in Adoncholaiminae are found from various water environment of the world. However, a checklist of all Adoncholaiminae species including full literature, especially information of experimental (not taxonomic) works, has not been updated for more than 40 years. A revised checklist of the subfamily Adoncholaiminae of the world is provided. It contains 31 valid and 13 invalid species names in four genera with synonyms, collection records, and full literature from 1860's to 2015 for each species. A literature survey of total 477 previous papers was conducted in this work, and 362 of them are newly added to checklist

Meiofauna in the Gollum Channels and the Whittard Canyon, Celtic Margin—How Local Environmental Conditions Shape Nematode Structure and Function

The Gollum Channels and Whittard Canyon (NE Atlantic) are two areas that receive high input of organic matter and phytodetritus from euphotic layers, but they are typified by different trophic and hydrodynamic conditions. Sediment biogeochemistry was analysed in conjunction with structure and diversity of the nematode community and differences were tested between study areas, water depths (700 m vs 1000 m), stations, and sediment layers. The Gollum Channels and Whittard Canyon harboured high meiofauna abundances (1054–1426 ind. 10 cm−2) and high nematode diversity (total of 181 genera). Next to enhanced meiofauna abundance and nematode biomass, there were signs of high levels of organic matter deposition leading to reduced sedimentary conditions, which in turn structured the nematode community. Striking in this respect was the presence of large numbers of ‘chemosynthetic’ Astomonema nematodes (Astomonema southwardorum, Order Monhysterida, Family Siphonolaimidae). This genus lacks a mouth, buccal cavity and pharynx and possesses a rudimentary gut containing internal, symbiotic prokaryotes which have been recognised as sulphur-oxidising bacteria. Dominance of Astomonema may indicate the presence of reduced environments in the study areas, which is partially confirmed by the local biogeochemical environment. The nematode communities were mostly affected by sediment layer differences and concomitant trophic conditions rather than other spatial gradients related to study area, water depth or station differences, pointing to small-scale heterogeneity as the main source of variation in nematode structure and function. Furthermore, the positive relation between nematode standing stocks, and quantity and quality of the organic matter was stronger when hydrodynamic disturbance was greater. Analogically, this study also suggests that structural diversity can be positively correlated with trophic conditions and that this relation is tighter when hydrodynamic disturbance is greater

Paracyatholaimus Micoletzky 1923

Paracyatholaimus Micoletzky, 1923 Wieser, 1954 a: 26, emended Diagnosis Cuticle punctated, lateral differentiation hardly developed. Six outer labial sensilla + four cephalic sensilla setose, in a single circle. Amphidial fovea multispiral. Cheilostoma armoured with twelve rugae; distinct dorsal tooth, often supplemented with smaller subventral teeth and occasionally other denticles in the stegostoma. Precloacal ventromedian supplements as setae­like organs half inserted into the body. Gubernaculum hardly dilated at the distal end and devoid of denticles or serrations. Tail conical or with more or less slender cylindrical distal portion. Type species Cyatholaimus dubiosus Bütschli, 1874. List of valid species 1 Paracyatholaimus arcticus Kreis, 1963. Kreis, 1963: 39 –40, fig. 20 A–C; Iceland. 2 Paracyatholaimus botosaneanui Andrássy, 1973. Andrássy, 1973: 259 –261, Abb. 9 A–C; Cuba. 3 Paracyatholaimus chilensis Gerlach, 1953. Gerlach, 1953 b: 19 –21, Abb. 9 a–e; Chile. 4 Paracyatholaimus diva sp. nov. Present paper. 5 Paracyatholaimus dubiosus (Bütschli, 1874). Bütschli, 1874: 48, fig. 31 a, b (= Cyatholaimus dubiosus); Kiel Bay. Micoletzky, 1922: 377 (to subgenus Paracyatholaimus). Meyl, 1954: 428 –429, Abb. 2 a–f; (Mediterranean). 6 Paracyatholaimus duplicatus Gerlach, 1964. Gerlach, 1964 b: 77 –78, Abb. 5 a–d; Maldive Islands. 7 Paracyatholaimus helicellus Wieser, 1954. Wieser, 1954 a: 27, fig. 107 a–c; Chile. 8 Paracyatholaimus intermedius (de Man, 1880). De Man, 1880: 16 –17 (= Cyatholaimus intermedius); De Man, 1884: 52 –54, fig. 25 – 25 f (= Cyatholaimus intermedius); Kattegat. Gerlach, 1953 a: 21 –22, Abb. 5; Baltic Sea. Gerlach, 1965: 127 –128, Abb. 9 a–c; Spitzbergen. Bussau, 1990: 170 –172, Abb. 3 A–C; North Sea, coastal dunes. 9 Paracyatholaimus lewisi Coomans, Vincx & Decraemer, 1985. Coomans et al., 1985: 268, fig. 2 A–F; Solomon Islands, freshwater pool on a coral island; no males described. 10 Paracyatholaimus occultus Gerlach, 1956. Gerlach, 1956: 91 –92, Abb. 29 a–c; Kiel Bay. 11 Paracyatholaimus paucipapillatus Gerlach, 1955. Gerlach, 1955: 265 –267, Abb. 7 a–e; El Salvador. 12 Paracyatholaimus pentodon Riemann, 1966. Riemann, 1966: 125 –127, Abb. 31 a–e; North Sea. Platt & Warwick, 1988: 282, fig. 128; East and West Scotland. 13 Paracyatholaimus pesavis Wieser & Hopper, 1967: 268 –269, pl. XVI, fig. 32 a–e; Florida. 14 Paracyatholaimus proximus (Bütschli, 1874). Bütschli, 1874: 49, fig. 30 a–b (= Cyatholaimus proximus); Kiel Bay. De Man, 1922: 239 –240, fig. 28 a, b (= Cyatholaimus proximus); North Sea. Micoletzky, 1924: 140 (to subgenus Paracyatholaimus). 15 Paracyatholaimus pugettensis Wieser & Hopper, 1967. Wieser, 1959: 37 –38, fig. 35 a–c (= Longicyatholaimus quadriseta Wieser, 1959, nec L. quadriseta Wieser 1954); Puget Sound, Washington, USA. Wieser & Hopper, 1967: 265. 16 Paracyatholaimus quadriseta (Wieser, 1954). Wieser, 1954 a: 13, fig. 98 a, b (= Longicyatholaimus quadriseta); Chile. Hopper, 1972: 69 (= Marilynia quadriseta). 17 Paracyatholaimus rotundus Gerlach, 1964. Gerlach, 1964 a: 25, Abb. 2 d–e; Red Sea. 18 Paracyatholaimus saradi Gerlach, 1967. Gerlach, 1967: 30 –31, Abb. 15 a–e; Red Sea. 19 Paracyatholaimus separatus Wieser, 1954. Wieser, 1954 b: 194 –196, Abb. 12 a–c; Mediterranean. 20 Paracyatholaimus spinulosus Jensen, 1985. Jensen, 1985: 253 –254, fig. 7 A–F; Gulf of Mexico. 21 Paracyatholaimus ternus Wieser, 1954. Wieser, 1954 a: 27 –28, fig. 108 a–e; Chile. 22 Paracyatholaimus truncatus (Cobb, 1914). Cobb, 1914: 60 –62, fig. 17 (= Cyatholaimus truncatus); Florida, fresh or brackish water. Micoletzky, 1922: 377 (to subgenus Paracyatholaimus). Finding of Riemann (1970) in a similar habitat at the Caribbean coast of Colombia may be doubtful because of the lesser male body length (1050 vs 1600 µ m), strong conical inner labial papillae, other pattern of four preanal supplementary organs (both posteriormost and penultimate organs are situated at the level of spicules while those of the type specimen are separated by much greater distances). 23 Paracyatholaimus vancouverensis Sharma & Vincx, 1982: 276 –278, fig. 15–23; British Columbia. 24 Paracyatholaimus vitraeus Gerlach, 1957. Gerlach, 1957: 140 –141, Abb. 21 l–o; Brazil. Remarks to species composition of the genus Paracyatholaimus Four species originally assigned to Paracyatholaimus, i.e. choanolaimoides Stekhoven, 1942, effilatus Stekhoven, 1946, major Kreis, 1928 and tyrrhenicus Brunetti, 1949, were later transferred to other genera by various authors (Gerlach & Riemann 1973) and are not considered here. Twenty­seven species of Paracyatholaimus are enumerated in the NeMys (Deprez et al. 2005) where P. parasaveljevi Allgén, 1935 is designated species inquirenda. Here four more other species are considered as species inquirendae because of insufficient type material lacking adult stages and/ or incomplete descriptions: Cyatholaimus chungsani Hoeppli et Chu, 1932; China. The species was shifted to Paracyatholaimus by Meyl (1954) and, missing in the NeMys list, is here considered as species inquirenda because of the very poor original description even lacking details actually indicating its affiliation with Paracyatholaimus. This is one of three species ascribed to Paracyatholaimus which were found in fresh­water habitats. Paracyatholaimus exilis (Cobb, 1898) Micoletzky, 1924 (= Cyatholaimus e. Cobb, 1898); Australia. The original description is based on only a female specimen and lacks illustrations. Paracyatholaimus oistospiculoides (Allgén, 1935) Wieser, 1954 (= Paracanthonchus o. Allgén, 1935); Norway Sea. The original description and drawings based on a single male specimen are too poor to determine the genus. Paracyatholaimus parasaveljevi Allgén, 1935; Norway Sea. Wieser (1954 a) qualified the species as species inquirenda. Paracyatholaimus tenuispiculum (Allgén, 1951) Wieser, 1954 (= Paracanthonchus t. Allgén, 1951); Hawaii. The original description and drawings are based on a single male specimen and lacks many details such as amphids and length of anterior setae. Illustrated guide for species of Paracyatholaimus (Figs 1 & 2, Table 1) The guide is a set of simplified images (Figs 1 & 2) constructed in some accordance with the approved practice of Platt (1984) and others (e.g., Platt & Warwick, 1998). Species of Paracyatholaimus differ from one another in rather fine morphological details concerning mainly length of anterior setae, number of turns in the multispiral amphidial fovea, supplementary organs and copulatory apparatus. The species can neither be disposed in a morphological continuum nor grouped in any evident morphological clusters. Therefore, it is not easy to develop a convenient polytomous or dichotomous key. I arrange the images of species in alphabetical order. An important component of the guide is Table 1, where the most important morphometric data are summarized. TABLE 1. Morphometry of valid Paracyatholaimus species (males). Species Characters L a c o.l.s., μ m am.w., m, amphid, c’ spic., m suppl. n. % c.b.d. number of turnsPublished as part of Tchesunov, Alexei V., 2008, Three new species of free­living nematodes from the South­East Atlantic Abyss (DIVA I Expedition) *, pp. 151-174 in Zootaxa 1866 on pages 153-157, DOI: 10.5281/zenodo.18377

Pomponema Cobb 1917

Pomponema Cobb, 1917 The genus was revised by Lorenzen (1972). An emended generic diagnosis of Pomponema is provided by Platt & Warwick (1988). According to NeMys (Deprez et al. 2005), twenty­nine Pomponema species have been described up until recently.Published as part of Tchesunov, Alexei V., 2008, Three new species of free­living nematodes from the South­East Atlantic Abyss (DIVA I Expedition) *, pp. 151-174 in Zootaxa 1866 on page 163, DOI: 10.5281/zenodo.18377

Desmodora

Desmodora de Man, 1889 Verschelde et al. (1998) proposed a taxonomic revision together with an emended generic diagnosis and a list of valid species of Desmodora. The list is supplemented in the NeMys database (Deprez et al. 2005).Published as part of Tchesunov, Alexei V., 2008, Three new species of free­living nematodes from the South­East Atlantic Abyss (DIVA I Expedition) *, pp. 151-174 in Zootaxa 1866 on page 169, DOI: 10.5281/zenodo.18377

A new tardigrade species of the genus Neostygarctus Grimaldi de Zio et al., 1982 (Tardigrada, Arthrotardigrada) from the Great Meteor Seamount, Northeast Atlantic

A new species of Neostygarctus Grimaldi de Zio et al., 1982 is described from the Great Meteor Seamount summit plateau in the Northeast Atlantic. Neostygarctus grossmeteori sp. nov. is characterized by the number and position of dorsomedian spines (five spines on the cephalic plate and each body plate and on the caudal plate, the spines decreasing in length backwards); the presence of eyes and of one or two pairs of ventral cervical spines; a transversal row of two to five short but strong spikes on the ventral side of the lateral body processes; only the internal claws of each leg provided with a normal accessory spine. The new species is related to N. acanthophorus Grimaldi de Zio et al., 1982 but differs by details of the dorsal body spines and the sculptures, the presence of ventral neck spines and ventral spikes on lateral body projections. Neostygarctus grossmeteori sp. nov. differs from two other known species of Neostygarctus, N. oceanopolis Kristensen et al., 2015 (Condor Seamont, NE Atlantic) and N. lovedeluxe Fujimoto & Miyazaki, 2013 (submarine cave NW Pacific), even more obviously by the number and position of dorsal body spines

A new tardigrade species of the genus Neostygarctus Grimaldi de Zio et al., 1982 (Tardigrada, Arthrotardigrada) from the Great Meteor Seamount, Northeast Atlantic

A new species of Neostygarctus Grimaldi de Zio et al., 1982 is described from the Great Meteor Seamount summit plateau in the Northeast Atlantic. Neostygarctus grossmeteori sp. nov. is characterized by the number and position of dorsomedian spines (five spines on the cephalic plate and each body plate and on the caudal plate, the spines decreasing in length backwards); the presence of eyes and of one or two pairs of ventral cervical spines; a transversal row of two to five short but strong spikes on the ventral side of the lateral body processes; only the internal claws of each leg provided with a normal accessory spine. The new species is related to N. acanthophorus Grimaldi de Zio et al., 1982 but differs by details of the dorsal body spines and the sculptures, the presence of ventral neck spines and ventral spikes on lateral body projections. Neostygarctus grossmeteori sp. nov. differs from two other known species of Neostygarctus, N. oceanopolis Kristensen et al., 2015 (Condor Seamont, NE Atlantic) and N. lovedeluxe Fujimoto & Miyazaki, 2013 (submarine cave NW Pacific), even more obviously by the number and position of dorsal body spines