Two new species of the genus Deontolaimus de Man, 1880 (Nematoda: Leptolaimidae) from mangrove ecosystems of Vietnam.

Two new species of the free-living marine nematode genus Deontolaimus (Leptolaimidae) are described from mangrove forests of the Can Gio Biosphere Reserve and Tien Yen, Quang Ninh, Vietnam. D. mangrovi sp. nov. is distinguished from D. papillatus de Man, 1880 and D. cangioensis sp. nov. by tail shape: conical and then elongated, without pointed tip. Deontolaimus cangioensis sp. nov. resembles D. papillatus in body shape, especially in the pointed tail terminus. D. cangioensis differs from D. papillatus in having a complicated gubernaculum with dorsally curved apophyses.

Revision of Cervonema Wieser, 1954 and Laimella Cobb, 1920 (Nematoda: Comesomatidae) with descriptions of two species from East Sea, Korea.

One new and one known species of the family Comesomatidae Filiepjev, 1918 were collected from marine sediments in the East Sea, Korea. Cervonema donghaensis sp. nov. is related to C. proximamphidum Tchesunov, 2000 and C. chilensis Chen & Vincx, 2000 but differs from them by the presence of the gubernaculum and by having outer labial setae and cephalic setae of unequal length. It differs from C. proximamphidum by having a rather shorter tail and the shape of the posterior widening of the pharynx, which has distinct muscular striation. Cervonema donghaensis sp. nov. differs from C. chilensis in body length, higher de Man's ratio c, and having a shorter cylindrical portion of the tail. Cervonema deltensis Hope & Zhang 1995 is considered as a junior synonym of C. tenuicauda (Schuurmans Stekhoven, 1950) Wieser, 1954. Specimens of Laimella filipjevi Jensen, 1979 from East Sea, Korea largely agree with the original description of Jensen (1979) of nematodes from the Western Baltic Sea, except for slight differences in length of cephalic setae and spicules. It also coincides well with the redescription of L. filipjevi by Tchesunov (2000) based on specimens from the White Sea. Pictorial keys for the identification of valid species in the genera Cervonema Wieser, 1954 and Laimella Cobb, 1920 are given.

Ethmolaimus riparius sp. n. and Paramononchus major sp. n. (Nematoda) from Lake Baikal, Russia.

Two new nematode species found in Lake Baikal (Russia) are described and illustrated. Ethmolaimus riparius sp. n. is morphologically close to E. pilosus Shoshin, 1998 and E. lanatus Shoshin, 1998. The new species differs from E. pilosus by the longer and thinner body (L = 1228-1501 µm, a = 26-34 vs L = 720-1070 µm, a = 19-23), larger stoma (26-32 µm long vs 19-24 µm long), longer spicules and gubernaculum (45-50 µm long and 21-25 µm long vs accordingly 32-37 µm long and 8 µm long). E. riparius sp. n. differs from E. lanatus by the longer body (L = 1228-1501 µm vs L = 680-1180), shorter cephalic setae (its length is equal 1.1-1.4 labial region diameter vs 1.6-2.1 labial region diameter) and longer spicules and gubernaculum (45-50 µm long and 21-25 µm long vs accordingly 25-30 µm long and 7-8 µm long). Paramononchus major sp. n is close to P. orientalis Gagarin & Naumova, 2012, but differs from it by the longer body (L = 5926-7820 µm vs L = 3081-3778 µm), longer spicules (410-475 µm long vs 208-238 µm long) and larger number of precloacal supplements (52-61 vs 21-24). Keys for the identification of valid species of the genera Ethmolaimus and Paramononchus are given.

Free living marine nematodes of the genus Parodontophora (Axonolaimidae) from the East China Sea, with descriptions of five new species and a pictorial key.

Five new species of free living marine nematodes belonging to genus Parodontophora are described from intertidal areas of Fujian Province, East China Sea. P. aequiramus sp. nov. is identified by the amphid with the same length of dorsal branch and ventral branch, opisthocephalic setae arranged as (2D-1V)2, precloacal supplements and armilliths present; Parodontophora irregularis sp. nov. is characterized by arranged irregularly opisthocephalic setae, excretory pore near cephalic setae at the anterior part of buccal cavity and precloacal supplements present; Parodontophora huoshanensis sp. nov. can be distinguished by the amphid 0.77-0.83 times the length of the buccal cavity, opisthocephalic setae arranged as (2D-1V)2 and precloacal supplements present; Parodontophora microseta sp. nov. is characterized by the amphid 1.71-2.1 times the length of the buccal cavity, opisthocephalic setae arranged as (1D-1V)2, precloacal supplements present and anterior gonad to the right and posterior gonad to the left of the intestine; Parodontophora paramicroseta sp. nov. is characterized by the amphid 1.35-1.5 times the length of the buccal cavity, opisthocephalic setae arranged as (1D-1V)2, precloacal supplements present and anterior gonad to the left and posterior gonad to the right of the intestine. A pictorial key to the valid species of Parodontophora Timm, 1963 is given.

Two known and one new species of Draconematidae and Epsilonematida (Nematoda, Desmodorida) from the White Sea, North Russia.

Morphological descriptions of three "walking nematode" species found for the first time in the White Sea are presented. Draconema ophicephalum (Claparède, 1863) (Draconematidae) and Epsilonema steineri Chitwood, 1935 (Epsilonematidae), both known from insufficient material and females only, are re-described and problems of their taxonomic identification as well as species compositions of respective genera are discussed. The new species Prochaetosoma marisalbi sp. n. (Draconematidae) differs from other Prochaetosoma species except P. longicapitatum (Allgén, 1935) in that the pharyngeal bulb lumen is not cuticularised, from P. longicapitatum by shape of body and rostrum, greater number of cephalic adhesive tubes, and from P. maertensi Decraemer, 1989 by having a relatively longer tail, fewer anterior adhesive tubes and longer spicules, besides lacking cuticular thickening in the pharyngeal bulb. Draconema hoonsooi, D. youngeouni, P.rochaetosoma beomseomense, P. brevicaudatum, P. byungilli, P. cracense, P. saheungi, P. sujungi, P. supseomense erected by Rho & Min (2011) are considered as invalid species while Prochaetosoma arcticum, P. lugubre and Epsilonema cygnoides are assumed as species inquirenda. From a phylogenetic tree based on the 18S rRNA gene, all three White Sea species adjoin to unidentified species of their respective genera.

One new genus and three new species of deep-sea nematodes (Nematoda: Microlaimidae) from the Southwest Pacific Ocean and Ross Sea.

New deep-sea nematodes of the family Microlaimidae are described from the Southwest Pacific Ocean and Ross Sea. Microlaimus korari n. sp. is characterised by annulated cuticle with longitudinal bars, round amphideal aperture slightly smaller than the cryptospiral amphideal fovea, spacious and heavily cuticularised buccal cavity with large dorsal tooth and right subventral tooth situated anteriorly relative to left subventral tooth, slender spicules 4.4 cloacal body diameters long, and gubernaculum 1.2 cloacal body diameters long with laterally curved distal end and swollen proximal end. Bolbolaimus tongaensis n. sp. is characterised by annulated cuticle with longitudinal bars, oval amphideal aperture and cryptocircular amphideal fovea situated between cephalic setae and only partially surrounded by cuticle annulations, and short spicules cuticularised along dorsal edge and at proximal end and with swollen portion near proximal end. Maragnopsia n. gen. is characterised by a minute, non-cuticularised mouth cavity without teeth, an elongated posterior pharyngeal bulb more than twice as long as it is wide, a single outstretched testis, and a conico-cylindrical tail 13-16 anal body diameters long. A list of all 83 valid Microlaimus species is provided. The present study provides the first microlaimid species records from deep-sea habitats (> 200 m depth) in the Southwest Pacific and Ross Sea. The presence of M. korari n. sp. on both the continental slope of New Zealand and Ross Sea abyssal plain suggests that this species has a wide geographical and depth distribution. However, molecular analyses will be required to confirm the identity of these two geographically disparate populations.

Loricophrya bosporica n. sp. (Ciliophora, Suctorea) epibiont of Desmoscolex minutus (Nematoda, Desmoscolecida) from oxic/anoxic boundary of the Black Sea Istanbul Strait's outlet area.

A suctorian ciliate Loricophrya bosporica sp. nov. is described from the body surface of nematodes of genus Desmoscolex collected in oxic/anoxic boundary of the Bosporus outlet area of the Black Sea. The new species differs from relative species L. sivertseni by development of its body, which takes no more than half, or a third of the lorica length, absence of crown-like projections at the lorica edge as for adhesive disk. From L. tuba new species differs by considerably shorter stylotheca and prevalence to nematode host instead of echinoderms.

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.

Swedish Plectida (Nematoda). Part 10. The genus Deontolaimus de Man, 1880.

The genus Deontolaimus de Man, 1880 is revised and the genus Camacolaimus de Man, 1889 is considered a junior synonym of Deontolaimus based on re-examination of type material of Camacolaimus tardus de Man, 1889 and C. barbatus Warwick, 1970. Two known and three new species of Deontolaimus are described from bottom sediments collected in marine habitats of Sweden: Deontolaimus uniformis (Cobb, 1920) comb. n., D. longicauda (de Man, 1922) comb. n., Deontolaimus catalinae sp. n., D. paraguillei sp. n. and Deontolaimus timmi sp. n. Deontolaimus catalinae sp. n. is characterized by body length of 1.3-1.7 mm; anterior-most somatic sensilla located short distance posterior to amphid; cephalic sensilla equal to 0.2 labial region diameter in length; amphidial fovea ventrally-unispiral with one turn, located in front of cephalic sensilla bases; excretory pore located short distance posterior to onchiostyle base; onchiostyle with bluntly rounded tip and subcylindrical body; male with alveolar supplements extending from anterior end to middle of body, tubular supplements absent; spicules 36-40 µm long; and didelphic female reproductive system. Deontolaimus paraguillei sp. n. is characterized by body length of 1.4-1.8 mm; anterior-most somatic sensilla located at level with onchiostyle; cephalic sensilla equal to 0.2-0.3 labial region diameter in length; amphidial fovea ventrally-unispiral with one turn, located at level with cephalic sensilla bases; excretory pore located just posterior to nerve ring level; onchiostyle with bluntly rounded tip and subcylindrical body; male with alveolar supplements extending from anterior end to about three body diameters in front of cloaca, tubular supplements absent; spicules 42-46 µm long; and didelphic female reproductive system. Deontolaimus timmi sp. n. is characterized by body length of 0.7-0.9 mm; anterior-most somatic sensilla located at level with onchiostyle; cephalic sensilla equal to 0.2-0.3 labial region diameter in length; amphidial fovea ventrally-unispiral with one turn, located just in front of cephalic sensilla bases; excretory pore located just posterior to nerve ring level; onchiostyle with triangular tip with bluntly rounded apex and strongly sclerotized dorsal edge, and subcylindrical body; male with alveolar supplements extending from anterior end to anterior part of intestine, tubular supplements absent; spicules 28 µm long; and didelphic female reproductive system. The following nomenclatorial changes are proposed: genera Acontiolaimus Filipjev, 1918, Camacolaimoides De Coninck & Schuurmans Stekhoven, 1933, Camacolaimus de Man, 1889, Digitonchus Cobb, 1920 and Ypsilon Cobb, 1920 are synonimized with the genus Deontolaimus de Man, 1880; Camacolaimus reykjanesi De Coninck, 1943 and Camacolaimus glauxicola Allgén, 1951a are considered junior synonyms of Deontolaimus papillatus de Man, 1880; Camacolaimus barbatus apud Pastor de Ward, 1984 is described as the separate species Deontolaimus catalinae sp. n.; Camacolaimus tardus apud Lorenzen, 1969 is considered to be the separate species Deontolaimus lorenzeni nom. n.; Camacolaimus tardus apud Timm, 1963 is described as the separate species Deontolaimus timmi sp. n.; Camacolaimus barbatus Warwick, 1970 is considered a junior synonym of Deontolaimus tardus (de Man, 1889) comb. n.; Camacolaimus parvus Timm, 1961 is transferred to the genus Deontolaimus as D. parvus (Timm, 1961) comb. n.; Digitonchus cylindricaudatus Chitwood, 1951 is transferred to the genus Deontolaimus as D. cylindricaudatus (Chitwood, 1951) comb. n.; Ypsilon exile Cobb, 1920 is transferred to the genus Deontolaimus as D. exilis (Cobb, 1920) comb. n.; Camacolaimus guillei de Bovee, 1977 is transferred to the genus Deontolaimus as D. guillei (de Bovee, 1977) comb. n.; Camacolaimus longicauda de Man, 1922 is transferred to the genus Deontolaimus as D. longicauda (de Man, 1922) comb. n.; Camacolaimus monhystera Gerlach, 1967 is transferred to the genus Deontolaimus as D. monhystera (Gerlach, 1967) comb. n.; Camacolaimus pontollittoralis Uzunov, 1977 is transferred to the genus Deontolaimus as D. pontollittoralis (Uzunov, 1977) comb. n.; Camacolaimus praedator de Man, 1922 is transferred to the genus Deontolaimus as D. praedator (de Man, 1922) comb. n.; Camacolaimus prytherchi Chitwood, 1935 is transferred to the genus Deontolaimus as D. prytherchi (Chitwood, 1935) comb. n.; Camacolaimus tardus de Man, 1889 is transferred to the genus Deontolaimus as D. tardus (de Man, 1889) comb. n.; Camacolaimus trituberculatus Blome, 1982 is transferred to the genus Deontolaimus as D. trituberculatus (Blome, 1982) comb. n.; and Digitonchus uniformis Cobb, 1920 is transferred to the genus Deontolaimus as D. uniformis (Cobb, 1920) comb. n. A taxonomic review and identification key for species of the genus Deontolaimus are also given.

New isolate of Mononchoides composticola Steel, Moens, Scholaert, Boshoff, Houthoofd & Bert, 2011 (Nematoda: Neodiplogasteridae) from Iran.

Mononchoides composticola was isolated during a survey on free living nematodes from vermicompost in Iran. This population of M. composticola is characterised by a dorsal claw-like tooth; 7-9 µm long and 3-5 µm wide, 14-15 finely visible longitudinal ridges on the cuticle, in which each ridge comprises two lines, long spicules (39-45 µm long), a short gubernaculum (15-17 µm or less than half of the spicule length), two pairs of precloacal papillae, five pairs of postcloacal papillae, papillae (v3) comprising three small papillae, and a long filiform tail (418-654 µm in females, 382-455 µm in males). Molecular analysis of M. composticola based on sequence of the 18S rDNA placed it close to M. composticola (GU943511; GU943512; from Belgium) and M. striatus (AY593924; from The Netherlands) in a well supported clade (1.00 posterior probability). Measurements, illustrations, LM and SEM pictures, and the phylogenetic position of M. composticola are given.

One new genus and five new nematode species (Monhysterida, Xyalidae) from Tonga and Kermadec Trenches, Southwest Pacific.

Little is known about the diversity and systematics of nematodes in hadal trenches (>6000 m depth). The analysis of core samples recently obtained from Tonga (10810 m) and Kermadec Trenches (8081 m) reveals the presence of a diverse nematode community in these extreme environments, and provides the deepest record for the phylum. Here, one new genus and five new species of the family Xyalidae are described. Lamyronema n. gen. is characterised by a large, tripartite buccal cavity and can be distinguished from other genera with similar buccal cavities mainly by the pharyngeal tissue almost completely surrounding the buccal cavity and by the presence of sub-cephalic setae positioned anteriorly to the amphideal fovea. Lamyronema horizonensis n. gen. n. sp. is characterised by the presence of 16-22 sub-cephalic setae, pronounced sexual dimorphism in the size of the amphideal fovea, and short, straight spicules. Daptonema amphorum n. sp. is characterised by short somatic setae, narrow head region, amphideal fovea relatively far from anterior body extremity, thin gubernaculum without apophyses, and cuticularised prevulvar uterine sac with two conspicuous rims. Manganonema kitasatoi n. sp., M. rowdeni n. sp., and M. majusculum n. sp. share traits that set them apart from other species of the genus, i.e., large body size (1100-2080 µm), presence of one pair of short setae posterior to the amphideal fovea, and male reproductive system with two testes. The latter trait necessitates amendments to the genus diagnosis.

Rhynchonema dighaensis sp. nov. (Monhysterida: Xyalidae): a marine nematode from the Indian coast with an illustrated guide and modified key for species of Rhynchonema Cobb, 1920.

A small bodied, free-living marine nematode, Rhynchonema dighaensis sp. nov., is described from the intertidal sand of the east coast of India. It is characterized by having a small buccal cavity, longer left spicule and symmetrical dorsal gubernaculum apophysis. Other species of the genus are discussed with their type locality. A modified key has been prepared for species of Rhynchonema with an illustrated guide. Species of Rhynchonema primarily differ from each other by the shape and size of the spicules, shape of the gubernaculum and dorsal apophysis, size of the buccal cavity and position of the amphid. 

Swedish Plectida (Nematoda). Part 8. The genus Onchium Cobb, 1920.

Four known and one new species of Onchium are described from bottom sediments collected in Skagerrak off the west coast of Sweden. The following known species are redescribed: Onchium ocellatum Cobb, 1920, O. metocellatum Wieser, 1956, O. parocellatum (Allgén, 1940) and O. robustum Gerlach, 1965. Onchium longispiculum sp. n. is characterised by the 1.34-1.77 mm long body, anterior body end without cephalic capsule, anteriormost somatic sensilla located posterior to onchiostyle base, ocelli absent, excretory pore located at basis of lips, onchiostyle uniformly cylindrical, alveolar supplements indistinct, tubular supplements absent, spicules arcuate and 44-65 µm long. The new species has a unique set of characters (absence of developed ocelli and very long somewhat asymmetrical spicules) separating it from all other known species of the genus Onchium. The following nomenclatorial changes are proposed: O. conicaudatum (Allgén, 1935) is considered a junior synonym of O. metocellatum; O. conicaudatum apud Wieser, 1951 is considered a synonym of O. minutum Kito, 1981. The diagnosis of the genus Onchium is emended and a tabular compendium and dichotomous identification key to species of the genus Onchium are provided.

Two new species and a new record of Comesomatidae (Nematoda, Araeolaimida) from Southern Hikurangi Margin, New Zealand.

We describe two new species and provide one new species record of the family Comesomatidae from a submarine canyon habitat on the Southern Hikurangi margin, New Zealand. Vasostoma hexodontium n. sp. is characterized by having an amphideal fovea with three turns, buccal cavity with six teeth and gubernaculum with long and straight caudal apophyses. Sabatieria dispunctata n. sp. is characterized by the absence of cuticle punctations, large amphideal fovea with 4.5 turns, pharynx with posterior bulb, absence of pre-cloacal supplements, strongly arcuate and cuticularized spicules, simple gubernaculum with short caudal apophyses, and vulva opening directed posteriorly. Laimella subterminata Chen & Vincx, 2000, which was originally described from the Beagle Channel and the Magellan Strait (Chile), is recorded from the Southwest Pacific for the first time. 

Paracomesoma minor sp. n. and Microlaimus validus sp. n. (Nematoda) from the coast of Vietnam.

Two nematode species isolated from sediments of the littoral zone of South China Sea on the coast of Vietnam are described and illustrated. Paracomesoma minor sp. n. is closely related to P. elegans Gagarin & Thanh, 2009 and P. lissum Gagarin & Thanh, 2009. It differs from the former species in the shorter body, longer and more slender tail, longer cephalic setae and shorter spicules, and from the latter species in the shorter body, longer cephalic setae, presence of cervical setae and smaller number of precloacal supplements in males. Microlaimus validus sp. n. is morphologically closest to M. citrus Gerlach, 1959 and M. nanus Blome, 1982 and differs from both species in the longer body, relatively shorter pharynx and relatively shorter and thicker tail. 

Swedish Plectida (Nematoda). Part 7. Setostephanolaimus tchesunovi sp. n. from the west coast of Sweden.

A new species of Setostephanolaimus, S. tchesunovi sp. n., is described from bottom sediments collected in the Skagerrak and Gullmarn Fjord off the west coast of Sweden. It is characterised by 1.0-1.3 mm long body, outer labial setae 6.5-8.5 µm long, cephalic setae 9-11 µm long, subcephalic setae 4-6 µm long, transversely-oval amphid, female with monodelphic opisthodelphic reproductive system, male with 6-9 tubular and without alveolar supplements, spicules arcuate and 54-64 µm long, gubernaculum with dorsal apophysis. A tabular compendium and dichotomous identification key to species of the genus Setostephanolaimus are provided. 

Swedish Plectida (Nematoda). Part 6. Neocamacolaimus parasiticus gen. n., sp. n.

A new genus Neocamacolaimus gen. n., with one new species N. parasiticus gen. n., sp. n. is described from the benthic polychaete Sphaerosyllis cf. hystrix collected in the Skagerrak off the west coast of Sweden. Neocamacolaimus gen. n. is placed in the family Camacolaimidae and is particularly characterised by having annulated cuticle with lateral alae; setiform cephalic sensilla located at level with amphids; amphidial fovea ventrally spiral; buccal cavity without armament; pharynx muscular; nerve ring located at base of pharynx; male reproductive system diorchic with outstretched testes; spicules weakly arcuate with straight manubrium; gubernaculum absent; alveolar supplements located in the pharyngeal region; tubular supplements absent; tail conoid; caudal glands and spinneret present. Juveniles of this genus are particularly characterised by their parasitic lifestyle and the following unique morphological features: lips form a dorso-ventrally elongated perioral disc with internal sclerotizations: one midventral and two dorsosublateral (right and left); cephalic sensilla setiform, subventral sensilla are noticeably longer than the subdorsal ones; intestine extends posterior to rectum and anal opening, forming a post-anal pouch.

Description of Trichodorus iranicus sp. n. (Diphtherophorina, Trichodoridae) from Iran.

Trichodorus iranicus sp. n. is described and illustrated based on morphological and molecular characters and morphometric data. It belongs to the T. lusitanicus morphospecies group based on the shape of the spicules and vaginal sclerotised pieces. Males have a body length of 844-942 µm, onchiostyle length of 59 µm, three cervical papillae (CP), curved spicules, 28-30 µm in length, with narrow mid-part, sometimes provided with a few bristles, and slightly developed manubrium. Females of the new species are 727-870 µm long with secretory-excretory pore located opposite anterior end of pharyngeal bulb, vagina length 46-57% of corresponding body width, with triangular to triangular-rounded sclerotised pieces 3.5 µm long, 1-2 µm apart from each other, and vulva a transverse slit. In its morphology, the new species resembles T. andalusicus, T. asturanus, T. azorensis, T. beirensis, T. lusitanicus, T. velatus and T. viruliferus and the morphological and morphometric differences separating T. iranicus from these known species are discussed. The D2-D3 region of 28S rDNA for the new species was amplified and the 679 bp newly-obtained sequence was used in a Bayesian inference (BI) analysis which confirmed the close relationship of the new species with T. lusitanicus morphospecies group members and placed it as a sister taxon to T. andalusicus in a well-supported clade that also includes T. asturanus.

Study of mononchids from Iran, with description of Mylonchulus kermaniensis sp. n. (Nematoda: Mononchida).

During a survey of soil nematodes in Iran, three species of predatory nematodes, including a new species of the genus Mylonchulus Cobb, 1916 were recovered. Mylonchulus kermaniensis sp. n. is characterised by its body length (1.2-1.4 mm), six rows of rasp-like denticles, the sixth line consisting of four denticles, female tail slightly sigmoid, sharply bent ventrad with digitate posterior portion slightly but clearly bent dorsad, (37-49 µm long, c=27.9-38.9, c'=1.2-1.7) with a terminal opening of spinneret. Two advulval papillae present, one is pre-vulval and the other one is located posterior to vulva. Furthermore, two other mononchid species namely M. cf. hawaiiensis (Cassidy, 1931) Goodey, 1951 and Mononchus truncatus Bastian, 1865 were also recovered from soil in the province of Kerman, Iran, the former representing a new geographical record for Iran. Measurements and illustration are provided for these three species. Molecular study of 18S rDNA region of M. cf. hawaiiensis demonstrated that the Iranian population compared with the nearest populations identified as M. hawaiiensis from Japan, shows 5 to 8 nucleotide differences. In addition, phylogeny of Mylonchulus is discussed and a checklist of the species of Mononchida from Iran is provided.

Mudwigglus gen. n. (Nematoda: Diplopeltidae) from the continental slope of New Zealand, with description of three new species and notes on their distribution.

Three new free-living nematode species belonging to the genus Mudwigglus gen. n. are described from the continental slope of New Zealand. The new genus is characterised by four short cephalic setae, fovea amphidialis in the shape of an elongated loop, narrow mouth opening, small, lightly cuticularised buccal cavity, pharynx with oval-shaped basal bulb, and secretory-excretory pore (if present) at level of pharyngeal bulb or slightly anterior. Mudwigglus gen. et sp. n. differs from other genera of the family Diplopeltidae in the combination of the following traits: presence of reflexed ovaries, male reproductive system with both testes directed anteriorly and reflexed posterior testis, and presence of tubular pre-cloacal supplements and pre-cloacal seta. Mudwigglus patumuka gen. et sp. n. is characterised by gubernaculum with dorso-caudal apophyses, vagina directed posteriorly, and short conical tail with three terminal setae. M. macramphidum gen. et sp. n. is characterised by long fovea amphidialis, cylindrical buccal cavity, gubernaculum without apophyses, vagina at right angle to body surface, and conico-cylindrical tail without terminal setae. M. plebeius gen. et sp. n. is characterised by cylindrical buccal cavity with cuticularised ring, gubernaculum with dorso-caudal apophyses, females with vagina directed posteriorly, and conico-cylindrical tail with two terminal setae. Diplopeluta nellyae Vinex and Gourbault, 1992 is transferred to Mudwigglus gen. n. based on observations of paratypes from New Caledonia, and of specimens from the New Zealand continental slope, which both show the presence of two testes facing anteriorly. M. macramphidum gen. et sp. n. was restricted to a single site on Chatham Rise crest (350 m water depth), whereas M. patumuka gen. et sp. was recorded from six sites on western Chatham Rise (350-2800 m). M. plebeius gen. et sp. n. was recorded from 13 sites on Chatham Rise and two sites on Challenger Plateau (264-2300 m). Mudwigglus nellyae comb. n. was restricted to two Challenger Plateau sites. All Mudwigglus gen. n. species appear to be restricted to subsurface sediments.