Deep-sea nematodes ( Comesomatidae ) from the Southwest Pacific Ocean : five new species and three new species records

The present study describes five new free-living nematode species and provides three new species records of the family Comesomatidae (genera Cervonema Wieser, 1954, Dorylaimopsis Ditlevsen, 1918, Hopperia Vitiello, 1969, and Kenyanema Muthumbi et al., 1997) from the continental margin of New Zealand, Southwest Pacific. Dichotomous identification keys are provided for all known species of Dorylaimopsis and Hopperia. Cervonema shiae Chen & Vincx, 2000 is recorded for the first time outside the type locality (Beagle Channel, Chile). C. kaikouraensis sp. nov. is characterised by amphideal fovea with 5.5 turns situated at 1.7 head diameter from anterior end, jointed outer labial setae, equal in length to cephalic setae, sperm dimorphism, and 5-6 small pre-cloacal supplements. C. multispira sp. nov. is characterised by amphideal fovea with 8.0-8.5 turns situated at 2.6-4.0 head diameter from anterior end, cephalic setae 2-3 μm long, slightly shorter than outer labial setae, presence of six uninucleated cells in males (potentially pseudocoelomocytes or supplementary excretory cells), 5 small pre-cloacal supplements, and strongly cuticularised, arcuate spicules with capitulum. C. proberti sp. nov. is characterised by amphideal fovea with 5 turns and located at < 1 head diameter from anterior end, cephalic setae 1.6-2.0 times longer than outer labial setae, and 8 small pre-cloacal supplements. Dorylaimopsis nodderi sp. nov. is characterised by cuticle with lateral differentiation consisting of three longitudinal rows of larger dots in the pharyngeal and caudal regions, two rows of larger dots in middle region of body, and spicules with rounded ventral projection at one third of spicule length from distal end, giving appearance of a joint. Hopperia ancora sp. nov. is characterised by short conical cephalic setae, spicules with hook-like projection at distal end, gubernaculum with bent apophyses, and 11-13 pre-cloacal supplements. H. beaglense Chen & Vincx, 1998 is recorded from Kaikoura Canyon, the first record of this species outside the type locality (Beagle Channel, Chile). Kenyanema monorchis Muthumbi et al., 1997 is also recorded for the first time outside the type locality (Indian Ocean).


Introduction
Nematode species of the family Comesomatidae Filipjev, 1918 are common on continental margins worldwide (Soetaert & Heip 1995;Vanhove et al. 1999;Muthumbi et al. 2011).Little is known, however, about the diversity and distribution of deep-sea (>200 m water depth) Comesomatidae in the Southwest Pacific (Miljutin et al. 2010).Two new species of this family were recently described from the continental slope of New Zealand (Leduc et al. 2012a).The present study describes five new species and provides three new species record belonging to the genera Cervonema Wieser, 1954, Dorylaimopsis Ditlevsen, 1918, Hopperia Vitiello, 1969, and Kenyanema Muthumbi et al., 1997 from the same region.

Sampling and laboratory methods
The present study focussed on three major bathymetric features of the New Zealand Exclusive Economic Zone (EEZ): Challenger Plateau, Chatham Rise and Kaikoura Canyon.Challenger Plateau encompasses water depths ranging from c. 400 to 3000 m in an area of generally low biological productivity to the northwest of the South Island, New Zealand (Murphy et al. 2001).Chatham Rise is a submarine ridge that extends eastwards from the South Island of New Zealand, over water depths ranging from c. 250 to 3000 m.The rise lies beneath the Subtropical Front (STF), a region associated with heightened primary productivity (Bradford-Grieve et al. 1997;Murphy et al. 2001).Kaikoura Canyon lies to the east of the South Island (~42˚S), and has been described as one of the most productive deep-sea benthic habitats known (De Leo et al. 2010).
Details of the study sites are given in Leduc et al. (2012a, b).Samples were collected along a transect at 178º30′E across Chatham Rise (nine sites, 350-3100 m water depth) in austral spring (September-October) 2001 during National Institute of Water and Atmospheric Research (NIWA) cruise TAN0116.Twenty-three additional sites between 240 and 1300 m water depths on Chatham Rise and Challenger Plateau were sampled in austral autumn-early winter (March-April and May-June) 2007 (NIWA cruises TAN0705 and TAN0707,respectively).Five sites (405-1420 m water depth) were sampled along the Kaikoura Canyon axis in May 2010 during NIWA cruise TAN1006.
Sediment samples were collected using an Ocean Instruments MC-800A multicorer (core internal diameter = 9.5 cm).Each sample consisted of one subcore of internal diameter 26 mm taken to a depth of 5 cm.Samples were fixed in 10% formalin and stained with Rose Bengal.Samples were subsequently rinsed on a 1 mm sieve to remove large particles and on a 45 μm sieve to retain nematodes.Nematodes were extracted from the remaining sediments by Ludox flotation and transferred to pure glycerol (Somerfield & Warwick 1996).Species descriptions were made from glycerol mounts using differential interference contrast microscopy and drawings were made with the aid of a camera lucida.All measurements are in μm, and all curved structures are measured along the arc.Type specimens are held in the NIWA Invertebrate Collection (NIC), Wellington.Anterior sense organs are defined as follows: papillae (<1 μm long), setiform papillae (1-2 μm), and setae (>2 μm) (Leduc & Wharton 2008).

Type species
Cervonema allometricum Wieser, 1954 Remarks Interspecific variation in the morphological characters of Cervonema species is relatively limited, and species within this genus should be identified using as many characters as possible (e.g., Barnes et al. 2012).The following characters, however, are particularly useful in species identification: relative length of outer labial setae and cephalic setae, shape and position of amphids, shape and size of spicules, presence/ absence and shape of gubernaculum, and tail length.Other traits, which have not always been included in earlier species descriptions, include presence/absence of jointed outer labial setae and presence /absence of sperm dimorphism.Pre-cloacal supplements are often difficult to observe using light microscopy and should not be used in isolation for defining species.

Description
Males Body cylindrical, tapering towards both extremities but more pronounced in tail region.Cuticle faintly striated, no lateral differentiation.Somatic setae short and sparse.Head not set-off by constriction.Inner labial papillae indistinct, six outer labial setae, and four slightly longer cephalic setae, the latter two in separate circles close to each other.Amphideal fovea spiral, at 6.0-6.5 turns, 1.8-2.3head diameters from anterior.Small buccal cavity, cup-shaped.Pharynx widening posteriorly into a weakly marked elongated bulb.Cardia short.Nerve ring near middle of pharynx length.Secretory-excretory pore near two thirds of pharynx length from anterior.Cellular body of ventral gland small-at level of cardia.Intestine wall consisting mostly of cells containing colourless granules, interspersed with clusters of clear globular inclusions.

Females
Similar to males, but with slightly larger maximum body diameter, amphideal fovea smaller, 5.0-5.5 turns.Reproductive system didelphic, opposed, ovaries outstretched, with anterior branch to left of intestine and posterior branch to right of intestine.Both types of sperm observed in uterus.Spermathecae not observed.Vulva at median or slightly post median.Granular vaginal glands present, pars proximalis vaginae surrounded by constrictor muscle.

Discussion
My specimens closely resemble the description of Chen & Vincx (2000) based on specimens from the Beagle Channel (255-257 m water depth), although specimens from Chatham Rise and Challenger plateau have slightly shorter cephalic setae (0.3-0.4 vs. 0.5 cbd) and longer tail (5.5-6.4 vs. 4.8 abd).The specimens are also characterised by sperm dimorphism (anterior testis with large oval sperm cells without nuclei, posterior testis with smaller nucleated sperm cells); Chen & Vincx (2000), however, did not provide details of the sperm in their description.This is the first record of this species outside the type locality.

Females
Similar to males, but with slightly larger maximum body diameter, amphideal fovea smaller, 4.5 turns.Reproductive system didelphic, opposed, with anterior branch to left of intestine and posterior branch to right of intestine.Terminal (i.e., distal) portion of anterior ovary bent in one paratype specimen (Fig. 4A), but not other paratype specimen; germinal portion of posterior ovary bent in both paratypes.Both types of sperm observed in uterus and spermathecae.Vulva at body median.Granular vaginal glands present, pars proximalis vaginae surrounded by constrictor muscle.

Diagnosis and relationships
Cervonema kaikouraensis sp.nov. is characterised by body length 1636 μm, amphid with 5.5 turns situated 1.7 head diameter from anterior end, jointed outer labial setae, equal in length to cephalic setae, anterior testis with large elongated sperm cells without nuclei, posterior testis with smaller nucleated sperm cells, 5 small pre-cloacal supplements, straight spicules 32 μm in length, and tail 5.5 abd.
C. kaikouraensis sp.nov.can be differentiated from all other species of the genus, except C. allometricum Wieser, 1954 andC. pseudodeltensis Barnes et al., 2012 by the presence of jointed outer labial setae.The presence of jointed outer labial setae in C. allometricum was not described in the original description of Wieser (1954) but was later noted by Lorenzen (1981).C. kaikouraensis sp.nov.can be distinguished from C. allometricum and C. pseudodeltensis by the absence of gubernaculum and gubernacular apophyses (gubernaculum with conspicuous posterior apophyses present in C. allometricum and C. pseudodeltensis).
The presence of jointed outer labial setae may have been overlooked in previous descriptions and may not be a reliable trait to use for differentiating between all species of Cervonema.C. kaikouraensis sp.nov.can further be differentiated from most other species of the genus (except C. deltensis Hope &Zhang, 1995 andC. papillatum Jensen, 1988 by the presence of sperm dimorphism.C. kaikouraensis sp.nov.differs from C. deltensis in body length (1636 vs. 1201-1237), length of cephalic setae (6 vs. 3-5 μm), amphideal fovea turns (5.5 vs. 3-5), position of amphid (1.7 vs. 1.4 hd from anterior), and absence of gubernaculum (plate-like gubernaculum in C. deltensis).C. kaikouraensis sp.nov.differs from C. papillatum in body length (1636 vs. 1140-1230), and by the absence of a weakly cuticularised cap surrounding the spicules proximally.The presence or absence of sperm dimorphism was not noted in the descriptions of C. brevicauda Gourbault, 1980 andC. jenseni Gourbault, 1980, but these species differ most notably from C. kaikouraensis sp.nov. in the presence of a gubernaculum (absent in C. kaikouraensis sp.nov.).C. brevicauda also has a shorter body length (800-1090 vs. 1636), shorter cephalic setae (3 vs. 6 μm), and shorter spicules (0.6 vs. 0.9 abd) than C. kaikouraensis sp.nov.C. jenseni can also be differentiated from C. kakouraensis sp.nov.by the greater number of amphid turns (7 vs. 5.5) and absence of supplements (5 in C. kaikouraensis sp. nov.).

Remarks
The presence of bent ovaries, as observed in C. kaikouraensis sp.nov., is unusual for the family Comesomatidae.The ovaries, however, are bent only in the terminal portion.Because the ovaries in both female specimens are quite large and occupy most of the available space in the pseudocoel (Fig. 3D), this trait is considered to be a secondary feature resulting from lack of space, rather than true reflexed ovaries.

Etymology
The species name is derived from the Latin multus (= much) and spiralis (= coil), and refers to the shape of the amphid.

Males
Body cylindrical, tapering towards both extremities, orange-brown colouration throughout.Cuticle faintly striated, no lateral differentiation.Somatic setae short and sparse.Head set-off by a depression at level of cephalic setae.Inner labial papillae indistinct, six outer labial setae, and four slightly shorter cephalic setae, the latter two in separate circles.Amphideal fovea spiral, 8.0-8.5 turns, situated 2.6-4.0 head diameters from anterior.Small buccal cavity, cup-shaped.Pharynx with small posterior bulb.Cardia short.Nerve ring near 60% of pharynx length from anterior.Secretory-excretory pore slightly posterior to nerve ring.Cellular body of ventral gland small, posterior to cardia.Six large uninucleated pseudocoelomocytes, 23 μm wide, 35-40 μm long, in anterior half of body, with 2 and 4 cells on either side of intestine in holotype, 3 cells on either side of intestine in paratype, each with single extension (or possibly duct) directed anteriorly (Fig. 6A).Intestine wall consisting mostly of cells containing small granules, interspersed with clusters of clear globular inclusions Reproductive system diorchic, opposed, outstretched.Anterior testis to left of intestine, posterior testis to right of intestine.Sperm cells small (up to 5×4 μm), globular, with lenticular nuclei situated peripherally.Spicules paired, equal, arcuate, 0.9-1.1 abd long, strongly cuticularised along entire length, with capitulum.Four pairs of small ejaculatory glands situated anteriorly to spicules (Fig. 5C).Small rectal gland present.Gubernaculum not observed.Five small, tubular pre-cloacal supplements, one precloacal seta.Tail conico-cylindrical, with several short caudal setae and three short terminal setae.Three caudal glands and spinneret present.

Females
Similar to males, but with smaller amphideal fovea, 7.5 turns.Large nucleated cells in anterior part of body not observed.Reproductive system didelphic, opposed, outstretched, with anterior branch to left of intestine and posterior branch to right of intestine.Spermatheca present, containing sperm.Vulva slightly post median.Granular vaginal glands present, pars proximalis vaginae surrounded by constrictor muscle.

Discussion
To my knowledge, this is the first time that the presence of large uninucleated cells is noted in the pseudocoelom of Cervonema specimens.Similar cells, usually situated laterally, and sometimes subventrally, have been described in Sabatieria celtica Southern, 1914(Riemann 1977), S. pulchra (Schneider, 1906) (Jensen 1979), S. breviseta Stekhoven, 1935, andS. punctata (Kreis, 1924) 8A).Head set-off by constriction at level of amphids.Inner labial papillae indistinct, six outer labial setae, and four longer cephalic setae, the latter two almost at same level.Cephalic setae 1.6-2.0times longer than outer labial setae.Amphideal fovea spiral, 5 turns, 0.5-1.0 head diameter from anterior.Small buccal cavity, cupshaped.Pharynx with rounded or oval terminal bulb.Nucleus of dorsal pharyngeal gland conspicuous.Cardia short.Nerve ring near middle of pharynx length.Secretory-excretory pore slightly posterior to nerve ring.Cellular body of ventral gland slightly posterior to cardia.Intestine wall consisting mostly of cells containing colourless granules, interspersed with clusters of clear globular inclusions (Fig. 8B).
Reproductive system diorchic, opposed, outstretched.Anterior testis to left of intestine, posterior testis to right of intestine.Oval-shaped sperm cells with lenticular nuclei situated peripherally (Fig. 7D).Two pairs of ejaculatory glands present.Spicules paired, equal, slightly arcuate, 0.7-0.9abd long, proximal end slightly cephalated, gradually tapering towards distal end.Gubernaculum not observed.Rectal gland surrounds spicules.Eight small, tubular pre-cloacal supplements, often difficult to distinguish, one precloacal seta.Tail conico-cylindrical, with several short caudal setae and three short terminal setae.Three caudal glands and spinneret present.

Females
Similar to males, but with slightly larger maximum body diameter, amphideal fovea smaller, 4-5 turns, slightly longer tail.Reproductive system didelphic, opposed, outstretched, with anterior branch to left of intestine and posterior branch to right of intestine.Vulva slightly pre median.Granular vaginal glands present, pars proximalis vaginae surrounded by constrictor muscle.

Diagnosis and relationships
Cervonema proberti sp.nov. is characterised by body length 1043-1144 μm, amphideal fovea with 5 turns and < 1 head diameter from anterior end, cephalic setae 1.6-2.0times longer than outer labial setae, sperm cells with lenticular nuclei, 8 small pre-cloacal supplements, and tail 4.5-5.9abd.Cervonema proberti sp.nov.can be distinguished from most other species of the genus by the amphid < 1 head diameter from anterior, compared to > 1 head diameter from anterior in most species (except C. hermani Chen & Vincx, 2000, C. chilensis Chen & Vincx, 2000, and C. proximamphidum Tchesunov, 2000)  chilensis, and C. proximamphidum).C. proberti sp.nov. is also characterised by a shorter tail than C. hermani (4.5-4.8 vs. 5.7-9.3 abd).C. proberti sp.nov.resembles Cervonema sp.B described by Barnes et al. (2012) based on one female specimen from the Korean west coast.My female specimens share several traits, including amphid close to anterior end, well-developed pharyngeal bulb with conspicuous pharyngeal gland nucleus, and cephalic setae longer than the outer labial setae.My specimens, however, have shorter body length (1183-1397 vs. 1727 μm), and greater ratio of cephalic setae length to outer labial setae length (1.6-2.0 vs. 1.3).Male specimens are required before the identity of the Korean species can be determined with certainty.Not noted in original description but described by Lorenzen (1981). 2 Micrograph in original description suggests presence of jointed outer labial setae, but they were not noted in the text (Hope & Zhang 1995, fig. 19).

Discussion
A total of 17 Cervonema species (including the three new species described herein) have been described so far.Differentiating between Cervonema species can be difficult due to relatively subtle differences in morphology.A summary of key morphological features of all known Cervonema species is provided to help identification (Table 3).
Buccal cavity usually strongly cuticularised; anterior portion shallow, sometimes with small pointed projections at border with vestibulum; posterior portion dilated, cylindrical or conical, usually with strongly cuticularised walls and three thornlike projections (teeth) at the border between the two portions.Spicules sometimes differentiated proximally, medially or distally.Gubernacular apophyses usually directed caudally, occasionally dorsocaudally.

Remarks
The genus Dorylaimopsis is similar in many respects to the genus Hopperia, but can be distinguished from the latter by the presence of longitudinal rows of dots as opposed to larger, irregularly-distributed dots in the lateral fields (sometimes arranged in transverse rows) in Hopperia.There are two exceptions: (

Males
Body cylindrical, tapering slightly towards both extremities.Cuticle punctate from level of amphid to near tail tip, with lateral differentiation consisting of three longitudinal rows of larger dots in pharyngeal and caudal regions, two rows of larger dots elsewhere.Cuticle in lateral field consisting of 1 μm thick basal layer, 4 μm thick median layer with forked columns (side view), and 2 μm thick cortical layer (Fig. 11A).Cuticle thinner in caudal region.Eight longitudinal rows of short, sparse somatic setae.Head set-off by constriction immediately posterior to cephalic setae.Six inner labial papillae, six outer labial papillae, and four cephalic setae.Anterior portion of buccal cavity cup-shaped.Posterior portion of buccal cavity cylindrical, cuticularised, narrow, 13-16 μm deep, with three cuticularised projections (teeth) at border to anterior portion.Amphideal fovea spiral, 2.5-3.0 turns, located immediately posterior to cephalic setae.Pharynx gradually swelling, not forming true bulb.Marginal tubes beginning from base of stoma.Cardia short.Nerve ring near middle of pharynx, situated anteriorly to secretory-excretory pore.Cellular body of ventral gland at level of cardia.Intestine wall with numerous small granules, interspersed with numerous regularly-spaced clear areas without granules, circular or irregular in shape (Fig. 9E).
Reproductive system diorchic, opposed, outstretched.Anterior testis to left of intestine, posterior testis to right of intestine.Spicules paired, equal, 1.8-2.9abd long, with rounded ventral projection at one third of spicule length from distal end, giving appearance of a joint.Spicules straight proximally, strongly bent at level of joint.Gubernaculum surrounding spicules, with wide triangular base and pair of long, straight caudal apophyses.Rectal gland surrounds gubernaculum.Twelve to sixteen tubular pre-cloacal supplements.Tail conico-cylindrical, with several short caudal setae and three short terminal setae.Three caudal glands.

Females
Similar to males, but with slightly smaller amphideal fovea, 2.5-2.75 turns.Reproductive system didelphic, opposed, outstretched, with anterior branch to left of intestine and posterior branch either to right or left of intestine.Vulva slightly pre median.Granular vaginal glands present, pars proximalis vaginae surrounded by constrictor muscle.

Diagnosis and relationships
Dorylaimopsis nodderi sp.nov. is characterised by cuticle with lateral differentiation consisting of three longitudinal rows of larger dots in pharyngeal and caudal regions, two rows of larger dots in middle region of body, cephalic setae 4-7 μm long, amphideal fovea with 2.5-3.0 turns, and spicules 98-112 μm long with rounded ventral projection at one third of spicule length from distal end, giving appearance of a joint.Dorylaimopsis nodderi sp.nov.differs from most other species of the genus (except D. punctata Ditlevsen, 1918 andD. magellanense Chen &Vincx, 1998) in the presence of spicules with ventral projections.D. nodderi sp.nov.can be distinguished from D. punctata by its smaller body length (1080-1656 vs. > 1900 μm), presence of three rows of enlarged dots in pharyngeal and caudal regions of both males and females (two rows in D. punctata), and fewer pre-cloacal supplements (12-16 vs. 18-22).D. nodderi sp.nov.can be distinguished from D. magellanense by its smaller body length (1199-1602 vs. 1708-2261 μm), and the smaller number of rows of enlarged dots in the lateral fields: three rows in pharyngeal and caudal regions (four or five in D. magellanense) and two rows in middle region of body (three or four in D. magellanense).Dichotomous key to all known species of Dorylaimopsis (modified from Jensen (1979) and Zhang (1992))  Dorylaimopsinae.Cuticle with lateral differentiation of irregularly-spaced larger dots, sometimes arranged in transverse rows; posterior portion of buccal cavity cylindrical, with three thorn-like teeth at border to anterior portion (except in H. hexadentata Hope & Zhang, 1995 which has six teeth); ovaries usually outstretched, reflexed ovaries sometimes present; spicules arcuate; gubernaculum with caudal or dorso-caudal apophyses.

Males
Body cylindrical, tapering slightly towards anterior extremity.Cuticle punctated from level of amphid to near tail tip, with lateral differentiation consisting of larger, irregularly-spaced dots.Eight longitudinal rows of short, sparse somatic setae.Head set-off by depression at level of cephalic setae.Six inner labial papillae, six outer labial papillae, and four conical cephalic setae in three distinct circles.Amphideal  Reproductive system diorchic, opposed, outstretched.Anterior testis to left of intestine and posterior testis to right of intestine in all specimens except one specimen with opposite arrangement.Sperm cells globular with outer radial lines.Spicules paired, equal, arcuate, 1.5-1.7 abd long, with swollen proximal end and central internal cuticularised projection (lamella) extending one fourth of spicule length from proximal end.Spicules with velum and conspicuous hook-like projection at distal end (Fig. 14C).Gubernaculum appearing to completely surround spicules, with bent dorso-caudal apophyses.Rectal gland surround distal end of spicules and gubernaculum.Eleven to thirteen tubular pre-cloacal supplements, one pre-cloacal seta.Tail long, conico-cylindrical, gradually tapering, with several short caudal setae and no terminal setae.Three caudal glands.Females Similar to males, but with slightly longer tail.Reproductive system didelphic, opposed, outstretched, with anterior and posterior branches either to left or right of intestine, but always on opposite sides.Vulva slightly pre median.Granular vaginal glands present, pars proximalis vaginae surrounded by constrictor muscle (Fig. 14D).
Hopperia ancora sp.nov.most closely resembles H. massiliensis Vitiello, 1969 andH. indiana Muthumbi et al., 1997 in body size, values of a, b, and c, size and shape of the cephalic setae, amphideal fovea, and tail, but can be distinguished from them (and all other species of the genus) by the presence of a conspicuous hook-like projection at distal end of spicules.Chen & Vincx, 1998 Figs 15-17,

Description
Males Body cylindrical, tapering slightly towards anterior extremity.Cuticle punctate from level of amphid to near tail tip, with lateral differentiation consisting of larger, irregularly-spaced dots.Somatic setae short and sparse, in four dorso-and ventro-lateral longitudinal rows.Six inner labial papillae, six outer labial papillae, and four cephalic setae in three distinct circles.Anterior portion of buccal cavity cupshaped.Posterior portion of buccal cavity cylindrical, strongly cuticularised, 24-26 μm deep, extending into three strongly cuticularised teeth at border to anterior portion.Teeth everted in some specimens.Cuticularisation of posterior portion of buccal cavity extends posterior to junction of marginal tubes with pharyngeal lumen (Fig. 15B).Amphideal fovea spiral, 3.0-3.5 turns, located immediately posterior to cephalic setae.Pharynx with oval posterior bulb.Cardia short.Nerve ring near middle of pharynx, situated anteriorly to secretory-excretory pore.Cellular body of ventral gland large (up to 37 x 20 μm), situated just posteriorly to cardia.Intestine wall with numerous small, clear granules, and small clusters of round, clear inclusions, sometimes with smaller orange-brown granules (Fig. 17B).

Females
Similar to males, but slightly greater maximum body diameter and smaller amphids, 3.0 turns.Reproductive system didelphic, opposed, outstretched, with anterior branch to left of intestine and (range: 29-36 vs. 30-41; mean: 34.2 vs. 39.1) and c values (range: 14-19 vs. 19-22; mean: 15.8 vs. 20.6),have 7-8 supplements instead of 6-7, and lack the supplement-like structure situated halfway down the ventral side of the tail (Fig. 15F).This is the first record of this species outside the type locality.
Within the Dorylaimopsinae, cuticularisation of the posterior buccal cavity does not usually extend into the pharyngeal lumen (i.e., cuticularisation stops before marginal tubes begin) (fig.2E in Jensen 1979).My specimens are unusual in that the cuticularisation of the buccal cavity extends into the anteriormost portion of the pharyngeal lumen (see Fig. 15B).It is unclear whether this is also a feature of the type specimens, however, because Chen & Vincx (1998) did not describe the marginal tubes.Dorylaimopsinae.Head region much narrower than the rest of the body; cuticle punctate and sometimes transverse striae are visible; inner and outer labial sensillae indistinct; four cephalic setae; tubular stoma without teeth; male reproductive system monorchic with outstretched anterior testis; females amphidelphic with outstretched ovaries; spicules arcuate; gubernaculum with caudal apophyses.

Description
Males Body cylindrical, tapering towards anterior extremity.Cuticle with transverse rows of dots, lateral differentiation consisting of larger, irregularly-spaced dots.Eight rows of short, sparse somatic setae.Head set-off by constriction immediately posterior to cephalic setae.Inner and outer labial sensillae indistinct, four cephalic setae.Amphideal fovea spiral, 2.5 turns, located at level of cephalic setae.Buccal cavity tubular, 4 μm deep, 1 μm wide, surrounded by pharyngeal muscles.Marginal tubes beginning from base of stoma.Pharynx gradually swelling, not forming true bulb, cardia short.Nerve ring near middle of pharynx, situated anteriorly to secretory-excretory pore.Cellular body of ventral gland near level of cardia.Intestine wall with numerous small, colourless granules, and clusters of clear circular inclusions, mostly in posterior portion of intestine (Fig. 18E).
Reproductive system monorchic with outstretched anterior testis to left of intestine.Mature sperm cells large, oval-shaped, up to 30 μm long and 13 μm wide.Spicules paired, equal, arcuate, 1.6-1.8abd long, with swollen proximal end and central internal cuticularisated projection (lamella) extending from proximal end over one fifth of spicule length.Gubernaculum with pair of straight caudal apophyses.Rectal gland surrounds posterior portion of spicules and gubernaculum.Two to three small tubular precloacal supplements, one pre-cloacal seta.Tail conico-cylindrical with swollen tip, several short caudal setae and three short terminal setae.Three caudal glands and spinneret.

Females
Similar to males, but with slightly greater maximum body diameter, amphideal fovea slightly smaller, 2.0-2.25 turns.Reproductive system didelphic, opposed, outstretched, with sperm distributed over uteri and with branches either to the right or left of intestine, but always on opposite sides.Vulva slightly post median.

Discussion
My specimens closely resemble the description of Kenyanema monorchis Muthumbi et al., 1997 based on specimens from the Indian Ocean (500-1112 m water depth).My specimens, however, have a smaller  No pre-cloacal supplements were observed in the original description of this species, but may have been overlooked.This is the first record for this genus outside the type locality.

Discussion
A recent study suggests that at least 775 nematode morphospecies (species that can be differentiated from others based on their morphology but which have not been formally described) are present on the continental margins of New Zealand (water depth 250-3100 m; Leduc et al. 2012b).Such high level of diversity is probably related to the wide range of environments encompassed by the country's Exclusive Economic Zone (e.g., Nodder et al. 2012).However, only 12 nematode species (or 1.5% of total) have been recorded/described from New Zealand's deep-sea habitats so far (Wieser 1956, Leduc et al. 2012a, present study).More work is clearly needed to obtain a better appreciation of New Zealand's deep-sea nematode fauna and its relationship to the fauna of other regions.
New records of C. shiae Chen & Vincx, 2000, H. beaglense Chen & Vincx, 1998, and K. monorchis Muthumbi et al., 1997   European Journal of Taxonomy 24: 1-42 (2012) wide distribution extending across ocean basins.Miljutin et al. (2010) noted that, out of 638 formally described deep-sea nematode species, 46 (including three Comesomatidae species) are likely to have a cosmopolitan distribution.The true proportion of deep-sea cosmopolitan species remains unknown due to paucity of data.Recent molecular evidence provides support for the existence of cosmopolitan nematode species in the deep sea (Bik et al. 2010), although the vast majority of families (including the Comesomatidae) remains to be investigated.
Abbreviations a = body length/maximum body diameter abd = anal body diameter b = body length/pharynx length c = body length/tail length cbd = corresponding body diameter hd = head diameter L = body length n = number of specimens %V = vulva distance from anterior end of body × 100/total body length

Fig. 2 .
Fig. 2. Cervonema shiae Chen & Vincx, 2000 and Cervonema kaikouraensis sp.nov.light micrographs.A. Large sperm cells without nuclei in anterior testis of C. shiae.B. Small nucleated sperm in posterior testis of C. shiae.C. Large sperm cells without nuclei in anterior testis of C. kaikouraensis sp.nov.D. Small nucleated sperm in posterior testis of C. kaikouraensis sp.nov.Arrows point to the lenticular nuclei situated on the periphery of the small sperm cells in the posterior testes of both species.Scale bar = 10 μm.

Table 3 .
Male morphological characters of all known Cervonema species.leduc d., Deep-sea nematodes from the Southwest Pacific Ocean

Table 4 Etymology
This species is named after Dr. Scott D. Nodder.

Table 6
on the continental margin of New Zealand suggest that these species have a