Subventral Teeth Research Articles

MINISIGMA VIETNAMICUM gen. nov., sp. n. И HOFMAENNERIA LONGISETOSA sp. n. (NEMATODA, CHROMADOREA) С КОРАЛЛОВЫХ РИФОВ ВО ВЬЕТНАМЕ

One genus and two new for science nematoda species, found in coral reefs of coast area of Vietnam are described. Minisigma gen. nov. characterized by the finely annulated cuticle with lateral files in the form of two parallel sclerotized ridges. At both edges of lateral files there are cuticular pores. Pharyngostoma armed with large dorsal tooth and two small subventral teeth. The fovea of amphids in the form double-turn spirals. There are ocellius. Pharynx bulb elongate-oval, poorly expressed. In front of cloaca four S-shaped sclerotized supplements. Minisigma vietnamicum gen. nov., sp. n. is described and illustrated Hofmaenneria longisetosa sp. n. in body size is close to H. keoladensis Khan, Husain, Sultana, 2005 and H. niddensis Gerlach, Meyl, 1957. It differs from first species by relatively shorter pharynx, relatively shorter tail, longer outer labial setae. It differs from second species by thinner body, relatively shorter tail, longer outer labial setae and shorter spicules.

A NEW FREE-LIVING NEMATODE GENUS TETRATOBRILUS GEN. NOV. (TRIPLONCHIDA: TOBRILIDAE) FROM WEST BENGAL, INDIA

A new free-living nematode Tetratobrilus dentatus gen. nov. sp. nov. under family Tobrilidae Filipjev, 1918 of the order Triplonchida Cobb, 1919 is described from a drowned paddy field soil (mud) in West Bengal, India. It is characterized by heavily sclerotized walls of anterior portion of the buccal cavity, a small dorsal tooth and two sub-ventral stomatal pockets longitudinally, one following another. The first pocket is fused with the posterior portion of the stoma, similar to the genus Epitobrilus, but differs in the presence of two adjacent teeth (vs. one) in the first pocket. The second pocket contains only one tooth. It also possesses smaller anterior setae (less than 40% of head diameter) and a subterminal setae. Males bear six characteristic pitcher-shaped supplements. Comprehensive details regarding the morphological structures, accompanied by figures and morphometric measurements, are presented in this report. An updated key to the genus and other genera of family Tobrilidae is also provided. Key Words: Stomatal pockets, sub-ventral teeth, Tobrilidae, new genus, new species

Two new species of Hypodontolaiminae (Nematoda, Chromadorida, Chromadoridae) from the Yellow Sea with a phylogenetic analysis in the subfamily.

Two new species of Hypodontolaiminae, Dichromadoramediasp. nov. and Neochromadoraparabilineatasp. nov., were isolated and described from the Yellow Sea, China. Dichromadoramediasp. nov. is characterized by four long cephalic setae, the amphidial fovea transverse oval in the male and slit-shaped in the female, the pharynx with a single posterior bulb, spicules curved and distally bifurcated, gubernaculum jointed, four (1+3) precloacal supplements papilliform, and the tail conical elongated with a short spinneret. Neochromadoraparabilineatasp. nov. is characterized by the buccal cavity with one large hollow dorsal tooth and two small subventral teeth, the pharynx with an obvious posterior bulb, spicules L-shaped and widened medially, gubernaculum boat-shaped, seven cup-shaped and equidistant precloacal supplements, and a long and gradually tapering tail. The phylogenetic analysis of maximum likelihood and Bayesian inference based on rDNA sequences confirmed the taxonomic positions of Neochromadoraparabilineatasp. nov. and Dichromadoramediasp. nov. within Hypodontolaiminae. Tree topology in Hypodontolaiminae shows the genera Neochromadora, Dichromadora, Ptycholaimellus, and Spilophorella as polyphyletic groups, and the genus Chromadorita as a paraphyletic group.

Description of Tobriloides sinensis sp. n. (Nematoda: Triplonchida: Tobrilidae) from Shanxi province, north China

Summary Tobriloides sinensis sp. n. is described from Shanxi province, China. It is characterised by relatively long body (1620-1935 m), two subventral teeth posterior to dorsal tooth, a short pharynx (b = 4.2-5.0), cardia three times longer than wide (91-98 μm long and 30-37 μm wide), female reproductive system amphidelphic, the vulva situated slightly posterior to mid-body (V = 59.0-69.9), and the tail relatively short (c = 8.4-9.7 and c′ = 4.6-5.7). The phylogenetic relationships of the new species were analysed using data from the near full length small subunit (SSU) and D2-D3 segments of large subunit (LSU) of rRNA genes. The status of T. sinensis sp. n. is discussed based on both morphological and molecular characteristics.

Description of Bolbolaimus major sp. nov. (Nematoda), from the Yellow Sea, China and phylogenetic analysis in Microlaimidae.

Bolbolaimus major sp. nov. is described from Rizhao coast along the Yellow Sea. The new species is characterized by relatively large body size, cuticle strongly annulated, six outer labial sensilla setiform, four cephalic setae long, buccal cavity wide with one large dorsal tooth and two small subventral teeth, amphidial fovea unispiral shaped oval in males and circular in females, spicules curved with swollen proximal end, gubernaculum with anterior-hooked dorso-caudal apophysis, and tail conical with short spinneret. A phylogenetic analysis of maximum-likelihood and Bayesin inference based on rDNA sequences confirms the taxonomic position of Bolbolaimus major sp. nov. within the family Microlaimidae. Tree topology in Microlaimidae shows genus Microlaimus as polyphyletic group and genera in Microlaimidae are closely related.

One new species of Oxyonchus ( ) (Enoplida: Nematoda) from the Yellow Sea of China

During the diversity assessment of marine nematodes in the China seas, a new species of Oxyonchus (Filipjev, 1927) De Coninck & Schuurmans Stekhoven 1933 was discovered from the Yellow Sea of China. O. boucheri sp. nov. is characterized by cuticle smooth; mouth opening surrounded by three lips separated by deep clefts; cephalic region with developed cephalic capsule; mandibles arch-shaped, rods linked with anteriorly transverse bar, two subventral teeth extend to the mandibles' anterior ends; thick outer and inner labial setae; six files of 2–4 cervical setae; conico-cylindrical tail without terminal seta; curved spicules with tapered distal ends; gubernaculum with dorso-caudal apophysis; a ventral tubular and 6–8 pairs subventral spinous precloacal supplements. The new species differs from other 17 congeners mainly in its conical inner and thick outer labial setae (vs. slender labial setae), files of 2–4 cervical setae present (vs. cervical setae absent), slender spicules with tapered distal ends (vs. spicules with capitulum), both ventral tubular and subventral spinous precloacal supplements (vs. only tubular supplement in males). Updated dichotomous key to the genus Oxyonchus were provided.

Molecular Phylogeny of the Genus Paracanthonchus (Nematoda: Chromadorida) with Description of P. yeongjongensis sp. nov. from Korea

During an investigation of the intertidal zone at Yeongjongdo Island, Incheon, Korea, a new species belonging to the genus Paracanthonchus was found and is reported. Paracanthonchus Mikoletzky, 1924 is the largest genus within the family Cyatholaimidae, and the species identification of this genus has been difficult mainly due to overlapping characteristics and a lack of genus/species-defining apomorphic characters. The new species is characterized by the buccal cavity, armed with one large dorsal tooth and two subventral teeth, the presence of lateral differentiation, seventy-six tubular precloacal supplements, and proximally paired gubernaculum. Alongside the description, we are updating the review of the genus by providing an up-to-date list of valid species, as well as a comprehensive tabular key to the genus with measurements of species-discerning characteristics. We also provide partial sequences of mtCOI, 18S and 28S rRNA to verify the new species belongs to the genus Paracanthonchus and to discuss the phylogeny of the family Cyatholaimidae as well as the genus Paracanthonchus. Our phylogeny agrees with previous findings that, while Cyatholaimidae forms a monophyletic clade, many genera within, including Paracanthonchus, are paraphyletic. For now, it appears that subfamilies are not well-represented by molecular means, and much more molecular data along with species defining morphological traits will have to be accumulated to meaningfully organize this family and the genus within.

Molecular and phenotypic characterization of two cryptic species of the predatory genus Mononchoides Rahm, 1928 (Rhabditida: Diplogastridae) and their congeneric affinities.

Based on morphometric, morphological and molecular characterization using partial small subunit 18S ribosomal DNA (rDNA) and the D2/D3 domain of large subunit 28S rDNA, we described a new species Mononchoides kanzakii collected from manure, and the known species Mononchoides composticola Steel, Moens, Scholaert, Boshoff, Houthoofd and Bert, 2011, isolated from the dung beetle Oniticellus cinctus (Fabricius, 1775). Phylogenetic trees based on the evolutionary model (GTR + I + G) were inferred by Bayesian inference algorithms. Mononchoides kanzakii sp. n. is characterized by 28-32 longitudinal ridges, discontinuous at level of stoma; amphidial apertures inconspicuous; metastegostom armed with thorn-shaped dorsal tooth; a flattened, claw-like right subventral tooth, and left subventral denticulate ridge with 12-14 fine denticles delimited by a group of five denticles in females vs. triangular, flattened right subventral tooth, 5-8 prominent denticles at left subventral sector in males; cloacal lips with a distinct rim; and gubernaculum with cuticularized, proximal and distal extensions of equal length, each constituting half of the length of the wider part of gubernaculum.

A new genus and species of the family Microlaimidae (Nematoda: Chromadorea) from intertidal sand of the Jeju Island, South Korea

As a part of the study of marine nematofauna of a sandy intertidal zone of Jeju Island (South Korea), a number of species have been proven as new for science. Here a new species representing a new genus of the family Microlaimidae (Chromadorea), Jejulaimus sinyangensis gen. n., sp. n. is described. The new monotypic genus is characterized by head set off abruptly from the body; anterior sensilla pattern 6+10, where six outer labial setiform sensilla together with four longer cephalic setiform sensilla are integrated in a common crown; pharyngostoma armed with a dorsal tooth and surrounded by convex muscular pharyngeal tissue, forming an anterior pharyngeal bulb which is distinctly set off from the rest of the pharynx; terminal pharyngeal bulb oval; ventral pore and ampulla of the excretory-secretory gland situated just posterior to the nerve ring; an only anterior testis present. The new genus bears some resemblance to the genera Bolbolaimus, Pseudomicrolaimus and Spirobolbolaimus in having an anterior pharyngeal bulb and in the position of the ventral pore of the excretory/secretory gland, but differs from them by anterior sensilla pattern 6+10, absence of subventral teeth in buccal cavity, and monorchic condition of male reproductive system.

A new species of a rare genus, Truxonchus quangi sp. n. (Mononchida, Anatonchidae) from bat xat nature reserve in Lao Cai Province, Vietnam

Truxonchus quangi sp. n. is described and illustrated from Vietnam. Females of the new species are characterized by large body size (L = 4.8-5.8 mm); barrel shaped buccal cavity of large size (105-113 x 66-73 µm) with one dorsal tooth and two subventral teeth posteriorly directed, of equal shape, size and apex position; dorsal tooth apex located 36-39% of buccal cavity length from its base; reproductive system didelphic-amphidelphic, vagina long, 39-45% of corresponding body width, with distinct par refringens vaginae, sclerotized pieces rounded in optical section; tail long, filiform, ventrally arcuate, with three small caudal glands in tandem and prominent subventral spinneret. The new species is close to T. dolichurus but differs by the larger buccal cavity, more anterior position of the dorsal tooth apex, more anterior vulval position and presence of advulval pores.

Pristionchus trametes n. sp. (Diplogastridae) isolated from the mushroom Trametes orientalis in Kyoto, Japan.

A new species of Pristionchus was isolated from fruiting bodies of the wood-decaying fungus Trametes orientalis collected from Kyoto, Japan. Attempts to culture it using bacteria, yeast, and freeze-killed wax moth larvae as food or substrate failed. The eurystomatous form of the species was not found in the collected material, and the species is typologically characterized by: its ‘small’ stoma with thin, membrane-like cheilostomatal plates, a small triangular right subventral tooth, thorn-like dorsal tooth, and small left subventral denticles; a short, blunt male tail spike; and a short, conical female tail. Although the posterior probability support was not high (66%), phylogenetic analysis of both small and large ribosomal RNA gene subunits suggests that the species is closely related to P. elegans and P. bucculentus. The new species can be distinguished from those two by its diagnostic characters comprising the stomatal morphology and male and female tail characters.

A new species of PomponemaCobb, 1917(Nematoda: Cyatholaimidae) from Northeast of Brazil, with reference to the taxonomic status of the genera ParapomponemaOtt, 1972 and PropomponemaOtt, 1972.

A new species of free-living marine nematode is described from Itapuã beach, northeast of Brazil. Pomponema veronicae sp. n. differs from other species of Pomponema by having buccal cavity with large pointed dorsal tooth, two subventral teeth and pairs of denticles, gubernaculum with two L-shaped lateral plates and having a membrane at its distal end that connects to L-shaped plate, and presence of a ventral orifice at distal end of L-shaped plates. It also differs from other species in the size of spicules and gubernaculum. The new species is considered most closely related to Parapomponema species because of the L-shaped lateral plates of gubernaculum, but the taxonomic status of Parapomponema was reviewed and Parapomponema and Propomponema are now synonymized with Pomponema. Pomponema cyatholaimoides is considered as a species inquirendum and Pomponema carinatum is accepted as Pomponema loticum. An updated identification key to species of Pomponema is included.

A new species of Pomponema Cobb, 1917 (Nematoda: Cyatholaimidae) from Northeast of Brazil, with reference to the taxonomic status of the genera Parapomponema Ott, 1972 and Propomponema Ott, 1972

A new species of free-living marine nematode is described from Itapuã beach, northeast of Brazil. Pomponema veronicae sp. n. differs from other species of Pomponema by having buccal cavity with large pointed dorsal tooth, two subventral teeth and pairs of denticles, gubernaculum with two L-shaped lateral plates and having a membrane at its distal end that connects to L-shaped plate, and presence of a ventral orifice at distal end of L-shaped plates. It also differs from other species in the size of spicules and gubernaculum. The new species is considered most closely related to Parapomponema species because of the L-shaped lateral plates of gubernaculum, but the taxonomic status of Parapomponema was reviewed and Parapomponema and Propomponema are now synonymized with Pomponema. Pomponema cyatholaimoides is considered as a species inquirendum and Pomponema carinatum is accepted as Pomponema loticum. An updated identification key to species of Pomponema is included.

Two new species of Xyalidae (Monhysterida, Nematoda) from the East China Sea.

Two new free-living nematode species of the family Xyalidae Chitwood, 1951 found in the East China Sea are described. Daptonema donghaiensis sp. nov. is characterized by epidermal chords of transparent cells present in most parts of the body; amphideal fovea approximately two times head diameter from anterior body end; L-shaped spicules with cephalate proximal end; tubular gubernaculums; and conico-cylindrical tail with long cylindrical portion. Cobbia heterospicula sp. nov. is characterized by slender body, buccal cavity with one dorsal tooth and two small subventral teeth; amphideal fovea far from the anterior body end; spicules that are paired but unequal in size, with right spicule longer and left spicule shorter; gubernaculums with dorsal apophyses; and conico-cylindrical tail with long filiform portion. An identification key to valid species of the genus Cobbia is given.

Cobbia bengalensis sp. nov. (Xyalidae: Monhysterida) from an eroding island of Sundarban, India.

A new species, Cobbia bengalensis sp. nov., of free-living marine nematodes is described from an island of Sundarban, Indian coast and compared with other eight valid species of the genus. Cobbia bengalensis sp. nov. is characterized and differentiated from the others by a unique combination of sexually dimorphic tail, arrangement of anterior sensilla, amphid position, presence of four subcephalic sensilla at the level of amphid, buccal cavity with one dorsal and two subventral teeth, elongated cardia and the shape of gubernaculum. Some previously recorded taxa thought to be the species of Cobbia has also been discussed. Wrongly recorded data for nematofaunal inventory from Indian water has also been criticized.

A re-description of Longicyatholaimus maldivarum Gerlach, 1964 (Nematoda, Cyatholamidae) with an emended identification key of the genus

Longicyatholaimus maldivarum was a species erected by Gerlach in 1964 from specimens found in the Maldivian archipelago. Due to the finding of additional representatives of this species, L. maldivarum is re-described with the addition of new morphological details mainly about males, because the information about female in the original description are very scarce. The newly found specimens showed a total body length higher than in the type specimens (1936–2063 µm vs. 1330 µm long) as well as the ratio of the total body length divided by maximum body diameter (22–28 vs. 27). The multispiral amphideal fovea showed 5 turns vs. 4 turns and Gerlach did not notice the presence of sub-ventral teeth that were clearly observed in the present specimens. The copulatory apparatus that perfectly matched the Gerlach description showed a central lamella mainly visible under confocal microscopy. A slightly lower ratio of the spicule length divided by anal body diameter (1 vs. 1.4) and longer gubernaculum (25–32 vs. 25 µm long) were noticed as well. Pre-cloacal supplements appeared very interesting for the presence of stout and conical setae protruding from cup-shaped structures. Supplements were more than in type species (8–9 vs. 7). Also the tail revealed some differences with a lower ratio of its total length divided by anal body diameter 6 vs. 7–8. The current list of 15 valid species of the genus was reduced to 10 species. In detail, we considered Longicyatholaimus heterurus and Longicyatholaimus sp. 3 species inquirendae for the absence of male specimens in the original description. We also excluded L. filicaudatus and L. tenuicaudatus because they were considered species inquirendae by Wieser & Hopper (1967) and L. zosterae because it was transferred by Lorenzen (1972) to the genus Paralongicyatholaimus. The new morphological details observed for Longicyatholaimus maldivarum and the modified number of valid species of the genus required also a revision of the identification key.

Three-dimensional reconstruction of the pharyngeal gland cells in the predatory nematode Pristionchus pacificus.

Pristionchus pacificus is a model system in evolutionary biology and for comparison to Caenorhabditis elegans. As a necromenic nematode often found in association with scarab beetles, P. pacificus exhibits omnivorous feeding that is characterized by a mouth-form dimorphism, an example of phenotypic plasticity. Eurystomatous animals have a dorsal and a sub-ventral tooth enabling predatory feeding on other nematodes whereas stenostomatous animals have only a dorsal tooth and are microbivorous. Both mouth forms of P. pacificus, like all members of the Diplogastridae family, lack the grinder in the terminal bulb of the pharynx resulting in a fundamentally different organization of several pharynx-associated structures. Here, we describe the three-dimensional reconstruction of the pharyngeal gland cells in P. pacificus based on serial transmission electron microscopical analysis of 2527 sections of 50 nm thickness. In comparison to C. elegans, P. pacificus lacks two gland cells (g2) usually associated with grinder function, whereas the three gland cells of g1 (g1D, g1VL, and g1VR) are very prominent. The largest expansion is seen for g1D, which has an anterior process that opens into the buccal cavity through a canal in the dorsal tooth. We provide the morphological description and fine structural analysis of the P. pacificus gland cells, the behavior of the pharynx and preliminary insight into exocytosis of gland cell vesicles in P. pacificus.

First record of spiral fovea amphidialis in Acantholaimus (Chromadoridae:Nematoda), with a description of a new species from shallow sediments of the South Atlantic and an emended diagnosis of the genus.

A new species of the genus Acantholaimus is described from the South Atlantic, in the Potiguar Basin off the continental shelf of northeast Brazil. Acantholaimus marliae sp. n. is characterized by the long body; numerous somatic setae arranged in four sublateral longitudinal rows; buccal cavity with five solid teeth (four subventral and one dorsal), with the largest tooth dorsally located and the most protuberant between the subventral teeth shaped similarly to a "bottle opener"; and spiral fovea amphidialis. Acantholaimus marliae sp. n. is the only species described for the genus that has a spiral fovea amphidialis. This is the fifth species of Acantholaimus described from shallow water. An emended diagnosis of the genus is provided.

Tripylella australis sp. nov. and Tripyla setifera Bütschli 1873 (Nematoda: Triplonchida: Tripylidae) from Australia.

This paper describes a new species of Tripylella and gives a new record of Tripyla (family Tripylidae) in Australia, and provides a key to species in the genus Tripylella. Tripylella australis sp. nov. is characterized by having females with a long body (1804-1832 μm), a=41-42, b= 4.4-4.5, c=10.3-11.3, c'=5.4-6.4 and V=51-54%, outer labial setae 13-14 μm long and cephalic setae 3.7-4.5 μm long in one whorl, dorsal tooth posterior to two subventral teeth, tail tapering uniformly, and four single caudal setae on the dorsal part of the tail. Males are similar to females, and have a long body (1870-2014 μm), a=50-55, b= 4.7-4.9, c=11.3-11.4, c'=5.8-6.0 and T=53-56%, horn-shaped spicules, 36-38 μm long, a straight gubernaculum 14-16 μm in length, tail tapering almost uniformly, and four caudal setae on the dorsal part of the tail. A key for identification of Tripylella species is presented. Tripyla setifera Bütschli 1873 is recorded for the first time in Australia, and is re-described.

Cyathoshiva amaleshi gen. n. sp. n. (Nematoda: Cyatholaimidae) from the coast of India.

A new genus, Cyathoshiva, of free-living marine nematodes from the subfamily Cyatholaiminae (family Cyatholaimidae, order Chromadorida), is described from the Indian coast. The new genus differs from other known Cyatholaiminae genera in having a unique combination of morphological characters: buccal cavity with well-developed dorsal tooth and two subventral teeth, proximally unpaired gubernaculum and non-cup shaped supplements. The type species Cyathoshiva amaleshi gen. n. sp. n. is characterized by having multispiral amphids with 4.5 turns, punctated cuticle with a weak lateral differentiation, a conical tail, three supplements possessing both tubular and setoid parts, and a gubernaculum with a serrated and dentate distal end.