Labial Setae Research Articles

Two new species of Microlaimidae (Nematoda: Microlaimida) from the Continental Shelf off Northeastern Brazil (Atlantic Ocean) with emended diagnosis and dichotomous key

New species of the genera Spirobolbolaimus and Ixonema (Nematoda: Microlaimidae) have been found in sediment samples collected in the South Atlantic, along the Continental Shelf break off Northeastern Brazil. Different to other Spirobolbolaimus species, S. pernambucanus sp. nov. possesses six outer labial setae and four cephalic setae with approximately the same length. Ixonema gracieleae sp. nov. differs from other species of Ixonema in having somatic setae on peduncles. This is the first time that new species of these taxa have been described for the Brazilian coast. An amendment of the diagnosis and a dichotomous key are proposed for both genera.

Two new species of Nematoda: Gairleanema pulchra sp. nov. (Tripyloididae) and Axonolaimus dimorphous sp. nov. (Axonolaimidae) from the Yellow Sea, China

Two new species of Nematoda, Gairleanema pulchra sp. nov. and Axonolaimus dimorphous sp. nov. are described from Rizhao coast, the Yelllow Sea. Gairleanema pulchra sp. nov. is characterized by six inner labial setae with bulbous swelling, six long outer labial setae and four short cephalic setae in one circle, amphidial fovea oval-shaped, spicules L-shaped with proximal end slightly cephalated, gubernaculum boat shaped with proximal end hooked anteriorly, seven oval-shaped precloacal supplements and tail conico-cylindrical. With the species description here two species are considered valid now in genus Gairleanema. Axonolaimus dimorphous sp. nov. is characterized by four long cephalic setae, amphidial fovea elongated loop in males and loop-shaped in females, spicules arcuated, gubernaculum with dorsal apophysis slightly directed to caudal position and tail conico-cylindrical with caudal setae. With the species description here 34 species are considered valid now in genus Axonolaimus.

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.

Corononema vulgare sp. n. and Hofmaenneria coralis sp. n. (Nematoda, Monhysterida) from coral reefs off the coast of Vietnam.

Two new nematode species of the order Monhysterida, found in coral reefs on the coast of Vietnam, are described and illustrated. Corononema vulgare sp. n. morphology is similar to C. thai Nicholas & Stewart, 1995 but differs from it by the shorter outer labial setae, shorter tail in males, and a different shape of the guiding lateral bodies in the spicular apparatus of males. Hofmaenneria coralis sp. n. morphology is close to H. niddensis Gerlach & Meyl, 1957 and H. optata Alekseev, 1983. The new species differs from the first species by having thinner body, a shorter and less slender tail, and shorter spicules. The new species differs from H. optata in having a longer body, shorter pharynx, shorter tail, and longer outer labial setae.

Three New Species of Free-Living Marine Nematodes of the Order Enoplida Filipjev, 1929 (Nematoda) from the Yellow Sea, China

Three new nematode species belonging to the order Enoplida were discovered in the muddy and sandy sediment along the Shandong peninsula coast of the Yellow Sea during a biodiversity investigation of marine nematodes in the Yellow Sea. They are named Belbolla octobulba sp. nov., Ironella gracilis sp. nov. and Oxystomina longiseta sp. nov. Belbolla octobulba sp. nov. is characterized by having eight pharyngeal bulbs; spicules arcuate, broad and even; gubernaculum with a pair of dorso-caudal apophyses, about a third of the length of spicule; and two winged precloacal supplements. Ironella gracilis sp. nov. differs from known species by body slender, buccal cavity divided into conical vestibulum and cylindrical posterior portion, three sclerotized teeth located in the vestibulum; both circles of outer labial setae and cephalic setae 10 µm apart; elongated spicules weakly arcuate with central strip and cephalate proximal end; gubernaculum conical without apophysis; and a tubular precloacal supplement with a long seta at its anterior end. Oxystomina longiseta sp. nov. can be distinguished from other known species by the relatively long outer labial setae and cephalic setae; arcuate spicules expanded proximally with a median rib; gubernaculum small and oblong; and two unequal precloacal supplementary setae, anterior one short, posterior one very long. Updated keys to eighteen species of Belbolla and keys to four species of Ironella are given.

Two New Nematode Species, Desmolaimus magnus sp. nov. (Monhysterida, Linhomoeidae) and Metadesmolaimus robustus sp. nov. (Monhysterida, Xyalidae), from the Yellow Sea, China with Phylogenetic Analyses within Linhomoeidae and Xyalidae

Two new species are described from the Rizhao coast along the Yellow Sea. Desmolaimus magnus sp. nov. is characterized by its relatively large body size, faintly striated cuticle, four long cephalic setae, a wide buccal cavity with cuticularized transverse rings, an amphidial fovea at the junction of the buccal cavity and pharynx, a pharynx without a bulb, curved spicules, a gubernaculum with a dorso–caudal apophysis, and an elongated conical tail. Metadesmolaimus robustus sp. nov. is characterized by its relatively large body size, coarsely striated cuticle, spacious buccal cavity with cuticularized rings, six inner labial sensilla setiform, six outer labial setae, and four long cephalic setae. The pharynx is notably muscularized, and the spicules are straight and jointed with a slightly swollen proximal end and a hooked distal end. The gubernaculum is brownish and comma–shaped, and the tail is conico–cylindrical with terminal setae. Phylogenetic analyses using maximum–likelihood and Bayesin inference, based on small subunit and D2–D3 fragment of large subunit rDNA sequences, place Desmolaimus magnus sp. nov. within the framework of the family Linhomoeidae and Metadesmolaimus robustus sp. nov. within Xyalidae. Topology trees at the family level show genera Desmolaimus and Metadesmolaimus as paraphyletic groups, the genus Terschellingia as a monophylectic group, the genus Theristus as a monophylectic group based on SSU sequence, the genus Daptonema as a monophylectic group based on LSU sequence.

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.

<i>Daptonema brzeskii</i> sp. n. and <i>D. rivale</i> sp. n. (Nematoda, Monhysterida, Xyalidae) from Mekong River Mouth, Vietnam

Two new nematode species of the genus Daptonema, D. brzeskii sp. n. and D. rivale sp. n., are described and illustrated based on the material collected from Mekong River Delta, Vietnam. Daptonema brzeskii sp. n. is close to D. lutosum Gagarin, 2021, D. dihystera Gagarin, Nguyen Vu Thanh, 2005 and D. hyalocella Aryuthaka, Kito, 2012 in the presence of postvulval uterus sac, and it is close to D. paraoxyuroides Nguyen Dinh Tu, Gagarin, Nguyen Vu Thanh, Nguyen Thi Xuan Phuong, Nguyen Thanh Hien, 2014 in the shape of spicular apparatus. From the former species it differs in the thinner body, slenderer tail, narrower labial region, shorter outer labial setae and spicules, larger pharyngostoma, and vulva located farther from the anterior body end. It differs from D. dihystera in the shorter body, narrowed labial region, shorter outer labial setae and spicules, and larger pharyngostoma. Daptonema brzeskii sp. n. differs from D. hyalocella in the thinner body, amphidial fovea located closer to the anterior body end, shorter outer labial setae, longer spicules, presence of gubernaculum, larger pharyngostoma, and vulva located farther from the anterior body end. From D. paraoxyuroides, D. brzeskii sp. n. differs in the presence of postvulval sac, longer body, slenderer tail, shorter outer labial setae and gubernaculum. Daptonema rivale sp. n. is similar to D. setihyalocella Aryuthaka, Kito, 2012 in shape of spicular apparatus and to D. brzeskii sp. n. in the shape of pharyngostoma. Daptonema rivale sp. n. differs from D. setihyalocella in the shorter and comparatively thinner body, shorter outer labial setae, spicules, and gubernaculum, bigger pharyngostoma, and vulva located farther from the anterior body end. Daptonema rivale sp. n. differs from D. brzeskii sp. n. in the longer body and outer labial setae, less slender tail, and vulva located farther from anterior body end.

<i>Amphimonhystrella tropica</i> sp. n. and <i>Oncholaimus mekongis</i> sp. n. (Nematoda) from the Mouth of the Mekong River, Vietnam

Illustrated descriptions of two new nematode species, Amphimonhystrella tropica sp. n. and Oncholaimus mekongis sp. n., found in the mouth of the Mekong River (Vietnam) are given. А. tropica is close to A. major Gagarin, Nguyen Dinh Tu, 2021 and A. paramonovi Phan Ke Long, Nguyen Dinh Tu, Gagarin by body size. It differs from first species in pharyngostoma shape, thiker body, longer tail and spicules, and absence of posterior uterus sac. It differs from second species in thicker body, longer spicules and another gubernaculum structure. Daptonema paramonovi Phan Ke Long, Nguyen Dinh Tu, Gagarin, 2020 is transferred to the genus Amphimonhystrella Timm, 1961: A. paramonovi (Phan Ke Long, Nguyen Dinh Tu, Gagarin, 2020) comb. nov. Dichotomy and pictorial keys for the identification of males of valid species of the genus Amphimonhystrella are given. Oncholaimus mekongis sp. n. is close to O. balli (Kreis, 1934) and O. menzeli Schneider, 1973 by body size and spicules length. It differs from both species in the presence of big spiny seta before to cloaca, position of ventral papillae at tail of males, thicker body, shorter outer labial setae and longer and slender males tail.

Two new species of genus Tripyloides (Nematoda, Enoplida, Tripyloididae) from the Chinese sea area

Abstract Two new free-living marine nematode species of genus Tripyloides were discovered in intertidal sediments along Rudong coast of the Yellow Sea and on Qi′ao Island of the South China Sea, respectively. They are described here as Tripyloides conicus sp. nov. and Tripyloides boucheri sp. nov. T. conicus sp. nov. is characterized by outer labial setae two-segments, amphideal fovea circular, buccal cavity with four chambers and with a distinct tooth at the bottom, spicules slender and straight, gubernaculum kidney-like with two lateral denticles at distal end, tail sexual dimorphism (elongated conical in males, conico-cylindrical in females). T. boucheri sp. nov. is characterized by body size small, outer labial setae stout, two-segments, amphidial fovea small, circular, narrow conical buccal cavity without distinct tooth, male with papilliform precloacal supplements, spicules slender, gubernaculum with two lateral denticles at distal end, tail conico-cylindrical and not swollen terminally. An updated dichotomous key for fifteen species of the genus is also given.

Two new nematode species of the genus Eutobrilus (Nematoda, Triplonchida) from Lake Baikal (Russia)

This paper describes and illustrates two new nematode species of the genus Eutobrilus found in Lake Baikal. Eutobrilus tsalolikhini sp. nov. is most similar to E. mirandus and E. obesus in body size and spicules length. It differs from E. mirandus in its thicker body, longer outer labial setae, larger stoma, and more supplements. It differs from E. obesus in a shorter tail, farther location of vulva from the anterior body end, longer outer labial setae, and more supplements. Eutobrilus olkhonensis sp. nov. is most similar to E. fortis and E. godlewskii in body size and supplements location but differs from both species in a thicker body, longer tail in males, shorter spicules, and fewer supplements.

Two new species, Parabathylaimus gracilis sp. nov. and Belbolla sinica sp. nov. (Nematoda: Enoplida), from Yangma Island of the Yellow Sea, China

Two new species Parabathylaimus gracilis sp. nov. and Belbolla sinica sp. nov. are described from Yangma Island, Yellow Sea. Parabathylaimus gracilis sp. nov. is characterized by six outer labial setae three-jointed, inner labial setae and cephalic setae unjointed, amphidial fovea unispiral with circular aperture and positioned at middle of buccal cavity, spicules paired and slightly curved, gubernaculum kidney-like and distal end heavily cuticularized with a pointed projection, tail conical without long subterminal setae. Belbolla sinica sp. nov. is characterized by short body length, posterior pharynx region with seven bulbs, spicules straight with proximal and distal end tapered and middle part thickened, gubernaculum short without apophysis, two small wing-shaped precloacal supplements well developed, tail conico-cylindrical with cylindrical portion short.

Geomonhystera longisoma sp. nov. и Mongolotheristus tsalolichini sp. nov. (Nematoda, Monhysterida) из устья реки Меконг, Вьетнам

The paper provides illustrated descriptions of two new nematode species of the order Monhysterida Filipjev, 1929 found in the Mekong River Delta in Vietnam. Geomonhystera longisoma sp. nov. is morphologically similar to G. longispiculata Prado-Vera, Ferris, Subbotin, 2018 and G. chiautzingoensis Prado-Vera, Ferris, Subbotin, 2018. However, the new member of the genus has а thicker body, longer outer labial setae, and shorter spicules. Mongolotheristus tsalolichini sp. nov. is similar to M. altaicus Tsalolichin, 1985, but it has amphidial foveas located closer to the anterior body end, shorter dorsal apophysis of the gubernaculum, and papillae-shaped precloacal supplements (absent in M. altaicus). The paper discusses the possibility of maintaining a separate status of the genus Mongolotheristus Tsalolichin, 1985, previously reduced to a synonym of the genus Daptonema Cobb, 1920.

Three new species of Mesacanthion Filipjev, 1927 (Nematoda: Thoracostomopsidae) from Argentine coasts

Three new species of Mesacanthion Filipjev, 1927 were found along Patagonian coasts (Argentina). Mesacanthion bifidum sp. nov. is characterized by short labial and cephalic setae, onchia of equal size, spicule arcuate, and gubernaculum with caudal apophysis, ending in two teeth. The species is related to M. virile (Ditlevsen, 1930) De Coninck & Schuurmans Stekhoven, 1933. However, the spicules and gubernaculum of both species are different in shape. Mesacanthion longigubernaculum sp. nov. is characterized by its long and slender body, striated cuticle, relatively long cephalic and cervical setae, onchia of different sizes, amphidial fovea lentil-shaped, spicule arcuate, gubernaculum surrounding the spicule, and tail conical-cylindrical with terminal setae. Mesacanthion sanantoniensis sp. nov. is characterized by its long and stout body, striated cuticle, long cephalic setae, onchia of different sizes, amphidial fovea pouch-shaped, spicule arcuate, gubernaculum with dorsal apophysis, and tail conical without terminal setae. Following the key of Jeong et al. (2019), the last two species are related to M. pali Wieser, 1959 and M. longissimesetosum Wieser, 1953, so we provide a key to differentiate the four species.

Eutobrilus godlewskii sp. nov. and Tobrilus gigas sp. nov. (Nematoda: Triplonchida) from Lake Baikal, Russia

Eutobrilus godlewskiisp. nov. and Tobrilus gigassp. nov. are described and illustrated based on the material collected from Lake Baikal, Siberia, Russia. The species Eutobrilus godlewskiisp. nov. morphologically is close to E. fortis (Tsalolikhin, 1972) and E. prodigiosusShoshin, 1988. From the former species it differs in the narrower labial region, longer outer labial setae, longer spicules and the absence of crystalloids. It differs from E. prodigiosus in the comparatively longer pharynx, another structure of stoma, longer spicules, another arrangement of precloacal supplements and the absence of crystalloids. Another new species, Tobrilus gigassp. nov. is the largest among valid species of the genus Tobrilus. Morphologically it is close to T. undophylusShoshin, 1988 and T. kamtschaticusGagarin, 2004. From the former species it differs by having a narrowed male body, longer outer labial setae and spicules. From T. kamtschaticus it differs in wider labial region, longer outer labial setae and spicules. This article presents two tables showing the morphological characteristics of males among valid species of the genus Eutobrilus and Tobrilus from Lake Baikal.

Morphological and molecular characteristics of Bastiania sinensis sp. n., Tripyla aquatica Brzeski & Winiszewska-Ślipińska, 1993 and T. setifera Bütschli, 1873 (Nematoda: Triplonchida) from Shanxi Province, North China

Summary This paper describes a new species of Bastiania, presents a new record and redescribes a known species of Tripyla. These nematodes are all in the order Triplonchida and were collected from Shanxi Province, North China. Bastiania sinensis sp. n. is characterised by having the female with a relatively slender body 1049-1295 μm long, dorsally arcuate after heat relaxation, with outer labial setae and cephalic setae in a single circle, an oval amphid, 7-8 laterodorsal cervical setae scattered in the pharyngeal region, orthometamenes and pseudocoelomocytes present, tail conoid with a mucron 1-2 μm long, two pairs of caudal setae present, a = 58.1-75.5, b = 4.0-4.6, c = 12.7-19.7, c′ = 4.1-7.8 and V = 61.1-67.7. Males were not found. Tripyla aquatica is recorded for the first time from China, and is redescribed. Tripyla setifera has been reported from China but without a detailed description – now provided. In addition, phylogenetic relationships among the species were analysed using data from the near full length small subunit (SSU) and D2-D3 segments of large subunit (LSU) of rRNA genes. Bastiania sinensis sp. n. is monophyletic with the Bastiania sequences available in GenBank, but is on an independent branch supporting its status as a separate species; T. aquatica and T. setifera are monophyletically clustered with known Tripyla species and grouped together with sequences from their respective species.

Two new nematode species of the genus Paratrilobus Micoletzky, 1922 (Nematoda, Triplonchida) from the water area of Lake Baikal (Russia)

This paper describes and illustrates two new nematode species of the genus Paratrilobus Micoletzky, 1922. The species Paratrilobus tankhoyensis sp. nov. was found at the estuary of the Pereyomnaya River (water area of Lake Baikal, near the Tankhoy railway station). Paratrilobus tankhoyensis sp. nov. is most similar to P. expugnator (Tsalolichin, 1976) in the body size, but differs in the comparatively thin body, shorter and thicker tail, shorter stoma and spicules. Another new species, Paratrilobus aquaticus sp. nov., was found in Posolsk Bank (natural underwater elevation of the bottom between the southern and central basins of Lake Baikal). The species is similar to P. granulosus Gagarin & Naumova, 2011 and P. ultimus (Tsalolichin, 1977) in the structure of the precloacal supplements. It differs from the former in the absence of crystalloids, a comparatively longer pharynx, longer stoma and outer labial setae as well as the absence of subterminal seta. It differs from the latter in a longer pharynx, stoma and longer outer labial setae as well as a longer and more slender tail. We also discuss diagnostic features of the males of the genus Paratrilobus.

Description of Two New Species of Free-Living Nematodes (Nematoda) from Vietnam

An illustrated description of two free-living nematode species—Leptolaimoides brevicaudatus sp. n. and Paramonhystera affinis sp. n.—from the water bodies of Vietnam is presented. L. brevicaudatus is similar to L. thermastris (Lorenzen, 1966); L. gangioensis Hoang Lai-Phu et al., 2009; and L. asiaticus Gagarin, Nguyen Vu Thanh, 2005 in regards to body size, but differs from these species by a shorter and less slender body, longer spicules, and the absence of precloacal supplements in males. Paramonhystera affinis sp. n. is morphologically similar to P. parabutschlii (Timm, 1961) and P. levicula (Lorenzen, 1972), but it has shorter and sparse somatic setae, six outer labial setae (versus four outer labial setae in both compared species), and shorter spicules.

Wieseria bicepes sp. nov. (Nematoda: Oxystominidae) from the South China Sea.

One unrecorded species of free-living marine nematodes from the South China Sea is described as Wieseria bicepes sp. nov. The present species is characterized by three circles of anterior sensilla nearly equal in length; four cephalic setae just behind the outer labial setae; oblong amphideal fovea with double contours and a handle-like protrusion at the base; tail tip bifurcate; spicules slightly curved with proximally cephalated and distally tapered; gubernaculum absent. The species is easily distinguished from the congeneric species by tail with a bifurcate tip and cephalic setae closely adjacent to labial setae.

New Genus and Two New Species of Free-Living Nematodes (Nematoda, Monhysterida) from Artificial Reservoirs in Vietnam

Descriptions and illustrations are presented for a new genus and two new species of free-living nematodes found in sediments of four artificial reservoirs for shrimp aquaculture. Paradaptonema gen. n. is morphologically close to Daptonema Cobb, 1920, but it has three glands around cardia that are absent in Daptonema, as well as a peculiar structure of the reproductive apparatus in males. Paradaptonema securum gen. n., sp. n. is characterized by a finely annulated cuticle, relatively long external labial setae, the presence of a postvulvar cell, and a peculiar shape of spicules and gubernacula. Thalassomonhystera longisoma sp. n. is morphologically close to Th. minor Gagarin, Nguyen Thi Thu, 2008 and Th. elegans Gagarin, Nguyen Vu Thanh, 2013, but differs from them in the length and slenderness of the body, as well as in the size of the external labial bristles and spicules.