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21Russian Journal of Nematology, 2011, 19 (1), 1 - 20
Six new species of the genus Onyx Cobb, 1891 (Nematoda: Desmodoridae) from coastal areas in
Vietnam
12 3 1
Nguyen Dinh Tu , Nic Smol , Ann Vanreusel and Nguyen Vu Thanh
'Department of Nematology, Institute of Ecology and Biological Resources, Vietnam Academy of Science and Technology (VAST). 18 Hoang Quoc Viet Str., Hanoi, Vietnam
e-mail: tu.nguyendinh@iebr.ac.vn 2Department of Biology, Nematology Section, Ghent University, B-9000 Gent, Belgium department of Biology, Marine Biology research group, Ghent University, B-9000 Gent, Belgium
Accepted for publication 20 October 2010
Summary. Six new species of the genus Onyx are described from different coastal zones in Vietnam based on samples collected between 2004 and 2010. Onyx cangionensis sp. n. is characterised by the fact that males have 14-16 equal-sized and equal-distantly arranged sigmoidal precloacal tubular shaped supplements. Onyx blomei sp. n. is characterised by sexual dimorphism in the shape of the amphidial fovea. The male has an atypical amphid with posterior part spiral shaped with 2.5 turns and anterior part hook shaped, whereas the amphidial fovea in the female is simply multispiral with 2.25 turns. Onyx orientalis sp. n. is characterised by its very long cephalic setae and the presence of 18 light-refractive, slightly S-shaped, precloacal tubular supplements in the males. Onyx cobbi sp. n. is also characterised by its sexual dimorphism in the shape of the amphidial fovea: an elongated loop in the male and a multispiral in the female. There are 15 slightly S-shaped, precloacal supplements. The anterior supplement is half the size of the others. Onyx paradimorphus sp. n. is characterised by a multispiral amphidial fovea, spicules regularly bent, strongly cuticularised, 15 S-shaped supplements and 5 papillae with setae within the spicules region. Onyx mangrovi sp. n. is characterised by 17-23 supplements with a complex structure: anterior part is sigmoidal-shaped, posterior part is hook-shaped and by its very short tail with dorsally curved tip. Key words: Desmodoridae, mangrove, marine nematodes, Onyx, shallow water, Vietnam.
The genus Onyx was first established and described as Onyx perfectus in 1891, the description being rather narrative in style. Before 1994, six species were described as: O. ferox (Ditlevsen, 1921); O. sagittarius Gerlach, 1950; O. septempapillatus Wieser, 1954; O. rugatus Wieser, 1959, O. perfectus Cobb, 1891 and O. dimorphus, Gerlach, 1963. Blome & Riemann (1994) described three new species from sandy beaches of northern New South Wales, Australia: O. macramphis, O. adenophorus and O. cannoni and the authors reviewed the genus Onyx annotating the differential characters of all species described so far. The precaudal position of the caudal glands in O. adenophorus is unique within the Chromadorea; however, it only has a diagnostic value at the species level. During several investigations carried out in different coastal zones of Vietnam, specimens of six
unknown Onyx species were collected, the descriptions of which are provided here.
MATERIAL AND METHODS
From November 2004 to April 2006, twenty stations were chosen for nematode sampling in the subtidal area in the Can Gio mangrove forest near Ho Chi Minh City, Vietnam. In March 2010 nematode samples were taken at the Tra Co beach of the Quang Ninh province, Vietnam. Sediment samples were collected to a depth of 10 cm with perspex cores (diam. = 3.5 cm). The samples were preserved in 4% neutralised formaldehyde heated to 60-70°C. The nematodes were extracted by Ludox solution. Under a stereomicroscope 200 nematodes (or all if lower numbers occurred) were picked out randomly. The transfer of the nematodes into pure glycerol was done following the method of De Grisse (1969). The nematodes were mounted into a small drop of
Fig. 1. Onyx cangioensis sp. n. A, C, D: holotype, A: head region; C: pharynx region; D: tail region and spicular apparatus; E: total view; B, F: allotype, B: head region; F: vulva region. Scale bars: A, B, D = 10 ^m, C = 20 ^m, E = 50 ^m. F = 40 ^m.
Fig. 2. Onyx cangioensis sp. n. A, C, D: holotype, A: head region; C: hollow dorsal tooth; D: spicular apparatus; B, E: allotype, B: head region; E: vulval region. Scale bars: 10 ^m. Arrows - advulvar setae.
Table 1. Measurements of Onyx cangioensis n. sp. (all measurement in ^m, except ratios).
Characteristic Holotype Paratypes Allotype Paratypes
¿2 ¿3 ¿4 ¿5 ¿6 91 92 93 94
Body length 685 693 736 679 713 759 808 547 711 810
a 21.8 21.5 21.9 20.9 22.5 22.9 24.9 16.0 20.2 22.1
b 5.9 5.6 6.1 5.1 5.4 6.3 6.7 4.3 6.0 6.0
c 10.1 9.6 8.5 9.9 10.2 10.9 11.7 8.7 9.5 11.6
c' 2.5 2.5 3.0 2.4 2.5 2.5 3.3 3.3 3.8 3.9
Head dia. 14.0 14.0 15.0 15.0 13.5 14.0 16.0 16.0 15.0 16.0
Outer labial setae 3.0 3.0 3.5 3.0 3.5 3.0 3.0 3.0 3.0 3.0
Cephalic setae 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0
Pharynx length 117 124 121 134 132 121 120 127 119 134
Max. body dia. 31.0 32.0 34.0 32.0 32.0 33.0 32.5 34.0 35.0 37.0
Dorsal tooth length 34.0 36.0 32.0 34.0 31.5 32.5 34.0 34.0 32.0 33.0
Amphideal fovea
width 8.5 8.0 8.0 8.0 8.0 8.0 7.0 7.0 8.0 8.0
c.b.d. 15.8 16.2 15.3 15.7 16.1 15.0 14.3 15.1 14.9 15.8
Vulva from anterior - - - - - - 400 387 361 398
V% - - - - - - 49.5 70.9 50.8 49.1
Spicule length 48.5 49.0 47.0 47.0 46.0 45.0 - - - -
Gubernaculum length 22.0 21.0 21.0 22.0 20.0 22.0 - - - -
S' 1.8 1.7 1.7 1.6 1.7 1.6 - - - -
Number of supplements 14 14 16 15 14 16 - - - -
Supplement length 12.0 12.5 13.5 12.0 13.0 13.0 - - - -
Anal width 27.3 28.3 28.5 28.7 27.5 27.9 21 18.9 19.8 18.2
Tail length 68.0 72.0 87.0 68.5 70.0 67.0 69.0 63.0 75.0 70.0
glycerol on a glass slide and sealed with a beeswax ring. Measurements and drawings were made with a microscope Olympus CH30RF200.
DESCRIPTION
Onyx cangioensis sp. n.
(Table 1; Fig. 1, 2)
Measurements. See Table 1.
Males. Cuticle reddish brown, finely striated. Head anteriorly rounded and not striated. Inner labial papillae not seen. Six outer labial papillae. Four short cephalic setae. Somatic setae (6 ^m long) regularly distributed in the entire body. Amphidial fovea located forward on the head, single loop, about 50% of corresponding body diameter. Buccal cavity large, deep 10 ^m, cup shaped, with strong hollow dorsal tooth (34 ^m length). Pharynx short, 117 ^m, anterior part of pharynx only weakly enlarged, posterior end enlarged to an oval bulb
with a slight constriction in the middle. Secretory-excretory system not seen. Reproductive system monorchic with anterior, outstretched testis (distal end 50 ^m from end of pharynx) subventrally right of intestine. Spermatozoa rounded and weakly light-refractive, small (2 ^m), vas deferens weakly and uniformly developed. Spicule regularly bent, 48.5 ^m long (1.8 times anal body diameter), rounded head, strongly cuticularised. The gubernaculum 22 ^m long, embracing the distal part of the spicule laterally. There are 14 strong (12 ^m long), sigmoidal precloacal tubular supplements, more or less of equal-size and equi-distantly arranged on the ventral side of the body. Tail short, 68 ^m (2.5 x anal body diameter), conical tip unstriated, dorsally with conspicuous, short setae (4 ^m). Caudal gland not seen.
Females. Similar to male in general appearance. Outer labial papillae, four cephalic setae. Amphidial fovea single loop, 7 ^m wide, similar to male.
Hollow dorsal tooth 34 ^m long. Vulva at mid-body. Reproductive system didelphic, amphidelphic with reflexed ovaries, with both branches on right side of the intestine. Two pairs of long, strong, subventral advulvar setae, 7 ^m long. Tail short, 68 ^m (3.3 times anal body diameter). Caudal glands not seen.
Differential diagnosis. Onyx cangioensis sp. n. is characterised by males with 14-16 equal-sized and equal-distantly arranged sigmoidal precloacal tubular supplements. This new species is similar to O. sagittarius Gerlach, 1950 in general body shape, type of amphidial fovea, arrangement of cephalic and somatic setae, but differs by having longer spicules (45 - 49 ^m in Onyx cangioensis sp. n. vs 35 ^m in O. sagittarius Gerlach, 1950), and showing a difference in number of precloacal supplements (14-16 in Onyx cangioensis sp. n. vs 22-24 in O. sagittarius Gerlach, 1950).
Type material. Holotype, adult male, slide UGMD 104152. Allotype, adult female, slide UGMD 104153, deposited at the Museum of Zoology University Ghent, Belgium. Paratypes. three females and five males (5$, 3$, slides UGMD 104152 - 56), deposited at the Museum of Zoology University Ghent, Belgium.
Type locality. Can Gio mangrove forest Ho Chi Minh City, Vietnam, subtidal at 0.5 m depth, sediment = silt, sample station CG16 (10029'196'' N and 106054'994'' E).
Etymology: The species name refers to Can Gio mangrove forest where it was found.
Onyx blomei sp. n. (Table 2; Fig. 3, 4)
Measurements. See Table 2.
Males. Cuticle brown-yellowish, finely striated. Head anterior rounded and not striated. Inner labial papillae not seen. Outer labial papillae. Four cephalic setae 6 ^m long. Four cervical setae (5 ^m long), just behind the amphidial fovea. Somatic setae (5 ^m) in the pharynx region shorter than at the rest of the body (12 ^m). Amphidial fovea 10 ^m high and 6.5 ^m wide and an atypical shape: posterior part spiral shaped with 2.5 turns (6 ^m) and anterior part hook shaped (6 ^m high x 4 ^m wide). Buccal cavity large, deep 10 ^m, cup shaped vestibulum, with strong hollow dorsal tooth (29 ^m long). Anteriorly the pharynx widened into a bulb, followed by a cylindrical part, posterior end enlarged to an elongated bulb of 50 ^m long and 24 ^m wide. Secretory-excretory system not seen. Reproductive system monorchic with anterior, outstretched testis (distal end 60 ^m from end of pharynx) subventrally right of intestine.
Spermatozoa rounded and weakly light-refractive, small (2 ^m), vas deferens weakly and uniformly developed. Spicule regularly bent, weakly cuticularised, 35 ^m long (1.5 times anal body diameter), rounded head. The gubernaculum 14 ^m long, embracing the distal part of the spicules laterally. There are eight, weakly light-refractive, precloacal supplements, (12 ^m long), slightly S-shaped, tubular, more or less equal size and equidistantly arranged on the ventral side of the body. Tail short, 83 ^m (3.7 x anal body diameter), conical tip unstriated. Four rows of each four somatic setae (6 ^m long) in tail region. Two additional long (13 ^m) setae on the dorsal side close to the tail tip. Caudal glands not seen.
Females. Similar to male in general appearance. Outer labial papillae, four cephalic setae. Amphidial fovea spiral with 2.25 turns, 5 ^m wide. Hollow dorsal tooth 26 ^m long. Vulva at mid-body. One egg present in uterus (52 * 32 ^m). Ovaries opposed, reflexed, left of the intestine. Tail short, 62 ^m long (3.3 times anal body diameter). Caudal glands not seen.
Differential diagnosis. Onyx blomei sp. n. is characterised by the sexual dimorphism in the shape of the amphidial fovea and the atypical shape of it in the male: spiral shaped with 2.5 turns posterior and hook shaped anterior; amphidial fovea in female multispiral with 2.25 turns. There are 7-8 weakly light-refractive, precloacal supplements and four rows of somatic setae in the tail region. The new species Onyx blomei is similar to O. dimorphus Gerlach, 1963 by its sexual dimorphism in the amphidial fovea, its general body shape, and its arrangement of cephalic and somatic setae, but differs by having shorter spicules (34.6 ^m in Onyx blomei sp. n. vs 45 ^m in O. dimorphus Gerlach, 1963) and showing a difference in number of precloacal supplements (7 - 8 in Onyx blomei sp. n. vs O. dimorphus Gerlach, 1963 having 10 strongly developed preanal supplements).
Type material. Holotype, adult male, slide UGMD 104154. Allotype, adult female, slide UGMD 104158, deposited at the Museum of Zoology University Ghent, Belgium. Paratypes. 2$, slides UGMD 104157 - 58, deposited at the Museum of Zoology University Ghent, Belgium.
Type locality. Can Gio mangrove forest Ho Chi Minh City, subtidal at 0.5m depth, sediment = silt, sample station CG16 (10o29'196'' N and 106o54'994'' E).
Another locality. Tra Co (21o28'.390'' N and 108o01'.231'' E), Quang Ninh province, Vietnam.
Etymology: The species name is given in honour of Dr Blome in recognition of his contribution to the nematode taxonomy and review of the genus Onyx.
Fig.3. Onyx blomei sp. n. A, C-E: holotype, A: head region; C: pharynx region; D: tail region and spicular apparatus; E: total view; B, F: allotype, B: head region; F: vulvar region. Scale bars: A, B, D: 10 ^m; C: 20 ^m, E, F: 50 ^m.
Fig. 4. Onyx blomei sp. n. A, C, D, F: holotype, A: head region; C: posterior of pharynx; D: hollow dorsal tooth; F: spicular apparatus. B, E: allotype, B: head region; E: vulval region. Paratype male. G: spicular apparatus. Scale bars: 10 ^m.
Table 2. Measurements of Onyx blomei sp. n. (all measurements in ^m, except ratios).
Characteristic Holotype ¿1 Paratypes Allotype 91
¿2 ¿3
Body length 756 697 722 620
a 27.3 25.5 25.2 15.4
b 5.3 5.9 5.4 5.3
c 9.2 9.6 9.0 10.0
c' 3.7 3.5 3.7 3.3
Head dia. 11.0 11.0 10.5 11.5
Outer labial setae 3.0 3.0 3.5 3.0
Cephalic setae 6.0 6.0 6.5 5.0
Pharynx length 143 117 132 117
Max dia. 28.0 27.0 29.0 40.0
Dorsal tooth length 29.0 27.0 26.0 26.0
Amphideal fovea
width 6.5 6.0 6.0 5.5
length 10.0 11.0 9.5 6.0
dia. 16.0 16.0 16.0 15.0
Vulva from anterior - - - 302.0
V% - - - 49.0
Spicule length 35.0 34.0 35.0 -
S' 1.5 1.7 1.6
Gubernaculum length 14.0 16.0 15.0 -
Number of supplements 8 7 8 -
Supplement length 12.0 12.5 13.5 -
Anal dia. 22.5 21.0 22.0 19.0
Tail length 83.0 73.0 80.0 62.0
Tail setae 12.5 12.0 13.0 12.5
Onyx orientalis sp. n. (Table 3; Fig. 5, 6)
Measurements. See Table 3.
Males. Cuticle brown-yellowish and finely striated. Head rounded and not striated. Inner labial papillae not seen. Six outer labial setae 3 ^.m long. Four cephalic setae very long, 16 ^.m long. Cervical setae 7 ^m long, situated at 10 ^m from amphidial fovea. Amphidial fovea a single donut-shaped loop, 7 ^m (45% corresponding body diameter). Buccal cavity with a small, cup-shaped vestibulum, 7 ^m deep, and with a strong hollow dorsal tooth (25 ^m length). Secretory-excretory system not seen. Pharynx 155 ^m length, anterior part of pharynx only weakly enlarged, posterior end enlarged to a double bulb with a slight constriction in the middle, lumen well sclerotised. Reproductive system monorchic with anterior, outstretched testis (distal end 55 ^m from end of pharynx) positioned subventrally and right of intestine. Spermatozoa rounded and weakly light-refractive, small, vas deferens weakly and uniformly developed. Spicules regularly bent, cephalate, strongly cuticularised, 38 ^m long (1.8 times anal body diameter). Gubernaculum 14 ^m long. Eighteen strongly light-refractive, slightly S-shaped, precloacal supplements 12 ^m long, tubular, more or less equal-sized and equi-distantly arranged on the ventral side of the body. Ten supplements in precloacal, staggered (in
two rows) position. Tail short, conical, 59 ^m long (2.8 x anal body diameter), conical, tip unstriated. Two groups of three 10 ^m long setae positioned in two lateral-ventral lines close to tail tip. Caudal glands not seen.
Females. Similar to male in general appearance. Outer labial papillae 3 ^m long, four cephalic setae 17 ^m long. Amphidial fovea single loop, 7 ^m wide (43% corresponding diameter). Hollow dorsal tooth 26.8 ^m long. Vulva at 635 ^m from anterior end (V = 61%). Ovaries opposed, reflexed. Two pairs of short, slender, subventral advulvar setae, 4 ^m long. Tail short with 56 ^m and conical (3 x anal body diameter). Caudal glands not seen. Differential diagnosis. Onyx orientalis sp. n. is characterised by its very long cephalic setae and 1718 light-refractive, slightly S-shaped, precloacal tubular supplements more or less equal-sized in the males, of which the 10 posterior supplements are staggered, and the two groups of three long subterminal setae on the tail.
Remark. Onyx orientalis sp. n. is close to O. adenophorus Blome & Riemann, 1994 by its double posterior pharyngeal bulb and the similar number of supplements and their staggered position, by the similar body shape, the shape of the amphidial fovea, the long cephalic setae and the somatic setae but differs by having longer cephalic setae (15-17 ^m
Table 3. Measurements of Onyx orientalis n. sp. (all measurement in ^m, except ratios).
Characteristic Holotype Paratypes Allotype 91 Paratypes
¿2 ¿3 ¿4 ¿5 92 93 94
Body length 978 1002 987 1003 974 1049 1094 1003 986
a 43.9 41.2 45.7 39.0 40.1 40.0 36.1 34.7 38.4
b 6.3 6.1 6.5 6.1 6.1 7.6 7.8 7.3 6.9
c 16.6 16.5 16.0 17.1 16.1 18.6 18.7 18.2 16.4
c' 2.8 2.7 2.7 2.8 2.5 3.0 3.0 2.7 2.8
Head dia. 14.0 13.0 12.5 15.0 15.0 13.0 14.0 14.0 13.0
Outer labial setae 3.0 3.0 3.0 3.0 3.5 3.0 3.0 3.0 3.0
Cephalic setae 16.0 17.0 16.0 17.0 15.0 17.0 17.0 17.0 17.0
Pharynx length 155 165 153 163 160 138 140 137 143
Max dia. 22.0 24.0 21.5 26.0 24.0 26.0 30.0 29.0 25.5
Dorsal tooth length 25.0 26.5 24.0 25.0 26.0 27.0 26.5 25.0 26.0
Amphideal fovea
width 7.0 6.5 7.0 6.0 7.0 7.0 7.0 6.0 7.0
c.b.d 15.5 16.5 16.0 17.0 15.0 16.0 17.0 15.0 17.0
Vulva from anterior - - - - - 636 621 643 620
V% - - - - - 61.0 57.0 64.0 63.0
Spicule length 38.0 39.5 40.0 30.0 38.5 - - - -
S' 1.8 1.8 1.7 1.8 1.6 - - - -
Gubernaculum length 14.0 15.0 15.0 15.0 15.0 - - - -
Number of supplements 18 18 17 18 17 - - - -
Supplement length 9.0 9.0 8.5 8.0 9.5 - - - -
Anal dia. 21.4 22.5 23.1 20.6 24.5 - - - -
Tail length 59.0 61.0 62.0 59.0 61.0 56.0 59.0 55.0 60.0
Tail setae 10.0 10.5 10.0 11.0 9.0 10.0 10.0 11.0 9.0
vs 10 ^m in O. adenophorus Blome & Riemann, 1994), and by the presence of two groups of long setae near the tail tip. Moreover, all supplements in Onyx orientalis sp. n. are equal in size.
Type material. Holotype, adult male, slide UGMD 104159. Allotype, adult female, slide UGMD 104159, deposited at the Museum of Zoology University Ghent, Belgium. Paratypes. 4$, 3$, slides UGMD 104159 - 62, deposited at the Museum of Zoology University Ghent, Belgium.
Another locality. Tra Co (21o28'.390'' N and 108°01'.231" E), Quang Ninh province, Vietnam.
Type locality. Can Gio mangrove forest Ho Chi Minh City, subtidal at 0.5m depth, sediment = silt, sample station CG13 (10°33'532" N and 106°53788" E).
Etymology: The species name refers to oriental mangrove forest and mudflat where it was found.
Onyx cobbi sp. n. (Table 4; Fig. 7, 8)
Measurements. See Table 4.
Males. Body wall transparent and finely striated. Head anteriorly rounded and not striated. Internal labial papillae not seen. Six outer labial setae (12 ^m long). Four cephalic setae very long: 21 ^m. Numerous and very long cervical setae (22 ^m). Amphidial fovea an elongated loop, 10 ^m high and 9 ^m wide (40% corresponding body diameter). Buccal cavity with vestibulum 12 ^m deep, cup shaped, with strong hollow dorsal tooth 39 ^m long. Secretory-excretory system not
seen. Pharynx 187 ^m in length, anterior part of pharynx only weakly enlarged, posterior end enlarged to an elongated double bulb with slight constriction in the middle, lumen well sclerotised. Reproductive system monorchic with anterior, outstretched testis subventrally right of intestine. Spermatozoa rounded to elongated and large (12.0 x 6.4 ^m), vas deferens weakly and more or less uniformly developed. Spicules regularly bent, strongly cuticularised, 46 ^m long (1.3 times anal body diameter), proximally rounded. Gubernaculum 26 ^m long. Fifteen strongly light-refractive, slightly S-shaped, precloacal supplements, (12 ^m long), tubular, equi-distantly arranged on the ventral side of the body; the anterior one about half the length of the others. Tail short, conical, 119 ^m (3.3 * anal body diameter), conical, tip unstriated. There are five setae positioned in two lateral-ventral fields on the tail, shorter than somatic setae (11 ^m). Caudal glands not seen.
Females. Similar to male in general appearance. However, there is the sexual dimorphism in the shape of amphidial fovea and shorter outer labial papillae (9 ^m long) and cephalic setae (19 ^m long). Amphidial fovea multispiral (2.25 turns), 8 ^m wide (30% corresponding diameter). Hollow dorsal tooth 41 ^m long. Vulva at mid-body. Ovaries opposed, reflexed. Tail 107 ^m long and conical (3.5 * anal body diameter). Two pairs of short, slender, subventral advulvar setae, 5 ^m long. Setae in tail 10 ^m long. Caudal glands not seen.
Characteristic Holotype ¿1 Paratypes Allotype 91 92
¿2 ¿3
Body length 1334 1544 1421 1214 1321
a 31.2 39.2 39.0 20.9 22.0
b 7.1 7.8 7.1 6.1 6.7
c 11.2 11.9 12.9 11.3 11.1
c' 3.3 3.7 3.0 3.5 3.8
Head dia. 27.0 28.0 25.0 27.0 25.5
Outer labial setae 12.0 12.0 12.5 9.0 10.5
Cephalic setae 21.0 22.0 21.0 19.0 18.5
Pharynx length 187 198 200 200 198
Max dia. 43.0 39.0 36.0 58.0 60.0
Dorsal tooth length 39.0 43.0 42.0 41.0 42.0
Amphideal fovea
width 9.5 8.0 8.0 8.0 9.0
high 10.0 10.5 11.0 8.0 10.0
dia. 24.5 24.0 22.0 26.0 25.0
Vulva from anterior - - - 560 610
V% - - - 46.0 46.0
Spicule length 46.0 42.0 45.0 - -
S' 1.3 1.2 1.2 - -
Gubernaculum length 26.0 26.0 28.0 - -
Supplements 15 16 15 - -
Anal dia. 36.0 35.0 36.0 30.0 31.0
Tail length 119 129 110 107 119
Tail setae 11.0 10.0 12.0 10.0 11.0
Table 4. Measurements of Onyx cobbi n. sp. (all measurements in ^m, except ratios).
Fig. 5. Onyx orientalis sp. n. A, D, E: holotype, A: head region; D: tail region and spicular apparatus; E: pharynx region; B, F: allotype, B: head region; F: vulva region; C: paratype male, ventral view with two rows of supplements. Scale bars: A-D: 10 ^m, E, F: 50 ^m.
Fig. 6. Onyx orientalis sp. n. A, E: holotype, A: head region; E: spicular apparatus. B, F, G: allotype, B: head region; F: posterior of pharynx; G: vulva region; C, D: paratype male, C: head region; D: supplements. Scale bars: A-G: 10 ^m.
Fig. 7. Onyx cobbi sp. n. A, C, D, F: holotype, A: head region; C: anterior part of supplement region; D: spicular apparatus; F: Total view; B, E: allotype, B: head region; E: total view. Scale bars: A - D: 10 цт. E: 100 цт; F: 50 цт.
Fig. 8. Onyx cobbi sp. n. A, D, E: holotype, A: Head region; D: Spicular apparatus; E: Hollow tooth; B, C, F: allotype, B: head region; C: posterior of pharynx; F: anterior of supplement region. Scale bars: A-F: 10 ^m.
Differential diagnosis. Onyx cobbi sp. n. is characterised by its sexual dimorphism in the shape of the amphidial fovea: an elongated loop in the male and a mutispiral in the female and the presence of 15-16 slightly S-shaped, precloacal supplements. Anterior supplement is half the length of the others. Onyx cobbi sp. n. is similar to O. perfectus Riemann, 1966 by its very long cephalic and somatic setae and by the number of supplements but differs by the sexual dimorphism in the amphidial fovea, absent in O. perfectus Riemann, 1966.
Type material. Holotype, adult male, slide UGMD 104163. Allotype, adult female, slide UGMD 104163, deposited at the Museum of Zoology University Ghent, Belgium. Paratypes. 2¿, 19, slides UGMD 104163 - 65, deposited at the Museum of Zoology University Ghent, Belgium.
Type locality. Can Gio mangrove forest Ho Chi
Minh City, subtidal at 0.5m depth, sediment = silt, sample station CG 13 (10o33'532'' N and 106°53'788" E) and CG16(10o29'196'' N and 106o54'994'' E).
Another locality. Tra Co (21o28'.390"N and 108o01'.231'' E), Quang Ninh province, Vietnam.
Etymology: The species name is given in honour of Dr Nathan Cobb, a famous nematologist.
Onyxparadimorphus sp. n.
(Table 5; Fig. 9, 10)
Measurements. See Table 5.
Males. The cuticle is reddish brown and finely striated. Head anterior rounded and not striated. Internal labial papillae not seen. Six outer labial setae (7 ^m long). Four cephalic setae very long (18 ^.m). Four cervical setae 18 ^m long, posterior to amphidial fovea. Amphidial fovea 19 ^m high and
16 ^m wide (50% corresponding body diameter), irregularly wound sausage-shaped spiral with three turns. Buccal cavity large, 13 ^m deep, anterior part cup shaped, with strong hollow dorsal tooth (43 ^m long). Secretory-excretory system not seen. Pharynx 178 ^m long, anterior part of pharynx only weakly enlarged, posterior end enlarged to a double bulb with a slight constriction in the middle. Reproductive system monorchic with anterior, outstretched testis subventrally right of intestine (distal end 120 ^m from end of pharynx). Spermatozoa small, rounded to elongated, vas deferens sclerotised and uniformly developed. Spicules regularly bent, strongly cuticularised, 43.5 ^m long (1.5 * anal body diameter), head drop-shaped. Gubernaculum 22 ^m long, 'candle'-shaped, embracing distal part of spicules laterally. Fifteen strongly light-refractive, slightly S-shaped, precloacal supplements 12 ^m long, tubular, more or less equal-sized and equi-distantly arranged on the ventral side of the body. The additional five papillae with setae within the spicules region; distance from cloaca to the first supplement 38 ^m. Tail 128 ^m (4.3 * anal body diameter) long, conical, tip unstriated. Setae in the tail region shorter than somatic setae (7 ^m). Caudal glands not seen.
Females. Not encountered in the samples.
Differential diagnosis. Onyx paradimorphus sp. n. is characterised by its multispiral amphidial fovea, spicules that are regularly bent, 15 strongly cuticularised, S-shaped supplements and 5 papillae with setae within the spicules region. Onyx paradimorphus sp. n. is similar to O. dimorphus Gerlach, 1963 by the long cephalic and somatic setae, and large elongated multispiral amphidial fovea. However, it differs by the number of turns of the amphidial fovea (O. paradimorphus sp. n. has 3 turns vs 2.25 in O. dimorphus Gerlach, 1963) and the number of supplements (15 vs 10 in O. dimorphus Gerlach, 1963). Additionally, O. paradimorphus sp. n. has 5 preanal papillae with setae in the anal region.
Type material. Holotype, adult male, slide UGMD 104193, deposited at the Museum of Zoology University Ghent, Belgium.
Type locality. Can Gio mangrove forest Ho Chi Minh City, Vietnam, subtidal at 0.5m depth, sediment = silt, sample station CG16 (10o29'196'' N and 106 o54'994'' E).
Etymology: The specific name refers to the similarity of amphidial fovea in new species with that of Onyx dimorphus Gerlach, 1963.
Table 5. Measurements of Onyx paradimorphus n. sp. (all measurements in ^m, except ratios).
Characteristic Holotype (S1) S2
Body length 1003 1196
a 25.3 30.1
b 5.6 -
c 7.9 10.1
c' 4.3 4.2
Head dia. 29.0 28.0
Outer labial setae 8.0 -
Cephalic setae 18.0 -
Pharynx length 178 -
Max dia. 40.8 40.0
Dorsal tooth length 44.0 -
Amphideal fovea - -
width 16.5 16.0
length 19.0 -
dia. 33.0 32.0
Spicule length 43.5 41.0
S' 1.5 1.5
Gubernaculum length 22.0 22.0
Number of supplements 15 15
Anal dia. 29.5 28.0
Tail length 128 119
Fig. 9. Onyxparadimorphus sp. n. A, B, C, D: holotype, A: Head region; B: Spicular apparatus; C: Pharynx region; D: Total view. Scale bars: A - B: 10 ^m. C: 20 ^m; D: 100 ^m.
Fig. 10. Onyx paradimorphus sp. n. A, D, C, E: Male 1, A: Amphidial fovea; B: Cephalic setae; C: Spicular apparatus; E: Total view; D: Male 2, Spicular apparatus. Scale bars: A-D: 10 ^m. E: 100 ^m. Arrows - supplements.
Table 6. Measurements of Onyx mangrovi n. sp. (all measurements in pm, except ratios).
Characteristic Holotype Paratypes Allotype 91 Paratypes
¿2 ¿3 ¿4 ¿5 ¿6 92 93 94 95 96
Body length 565 591 523 568 591 546 520 552 543 581 590 562
a 12.9 14.3 12.9 13.1 13.3 12.9 8.9 13.1 9.0 10.3 11.4 9.8
b 4.0 3.8 4.0 4.0 3.9 3.8 3.5 3.9 3.7 3.7 3.7 3.9
c 16.2 17.8 17.4 19.2 16.6 15.7 16.3 17.7 17.8 16.6 19.9 17.8
c' 1.3 1.3 1.2 1.1 1.4 1.3 1.0 1.3 0.9 1.1 1.0 0.9
Head dia. 15.1 16.6 17.2 15.3 14.8 13.6 16.0 - - - - -
Oesophgus length 141 154 132 143 151 143 150 141 147 159 161 144
Max dia. 44.0 41.0 41.0 43.0 45.0 42.5 59.0 42.0 60.5 56.0 52.0 57.0
Dorsal tooth length 34.0 31.0 30.0 34.0 36.0 33.0 45.0 32.0 40.0 35.5 33.0 34.0
Amphideal fovea
width 6.0 7.0 6.5 6.0 - - 4.0 - - - - -
dia. 17.0 18.0 16.0 16.5 - - 14.0 - - - - -
Vulva from anterior - - - - - - 316 316 304 320 320 300
V% - - - - - - 61.0 57.0 56.0 55.0 54.0 53.0
Anal dia. 27.0 25.0 24.0 27.5 26.0 27.0 30.5 24.0 33.0 33.0 30.0 35.0
Number of supplements 17.0 22.0 20.0 17.0 19.0 23.0 - - - - - -
Supplement length 13.0 12.5 13.5 12.0 13.5 12.5 - - - - - -
Spicule length 38.0 39.0 40.0 37.0 36.0 40.0 - - - - - -
S' 1.4 1.6 1.7 1.3 1.4 1.5 - - - - - -
Gubernaculum length 14.0 13.0 14.0 13.0 13.0 14.5 - - - - - -
Tail length 35.0 33.0 30.0 30.0 35.5 35.0 32.0 31.0 30.5 35.0 30.0 31.5
Tail length portion 11.0 11.0 10.5 11.5 11.0 10.5 13.0 13.5 12.5 12.0 13.0 12.5
Onyx mangrovi sp. n. (Table 6; Fig. 11, 12)
Measurements. See Table 6.
Males. Cuticle reddish brown, finely striated. Head anteriorly rounded and not striated. Inner labial papillae and outer labial papillae not seen. Four cephalic setae 3 pm long. Amphidial fovea single loop, 6 pm wide (47% corresponding body diameter). Buccal cavity large, anterior part 12 pm deep and cup shaped, with strong hollow dorsal tooth (34 pm long). Pharynx short 141 pm, anterior part of pharynx only weakly enlarged, posterior end enlarged to elongated bulb with slight constriction in the middle. Secretory-excretory system not seen. Reproductive system monorchic with anterior, outstretched testis (distal end 25 pm from end of pharynx) positioned subventrally and left of intestine. Spermatozoa rounded and weakly light-refractive, vas deferens weakly and uniformly developed. Spicules regularly bent, 38 pm long (1.4
times anal body diameter), heads rounded, strongly cuticularised. Gubernaculum 14 pm long. Seventeen strong, 13 pm long supplements; each proximally sigmoidal in shape and distally hook-shaped. Tail short, 35 pm (1.3 x anal body diameter), conical with tail tip curved dorsally at about 2/3 of tail length; tip unstriated over 9 pm, several short setae 4 pm present. Caudal glands not seen.
Females. Similar to males in general appearance. Inner and outer labial papillae not seen, four short cephalic setae 3 pm long present. Amphidial fovea single loop 4 pm wide shaped as in male. Hollow dorsal tooth 45 pm long. Vulva at 316 pm from anterior end (V = 61%). Ovaries opposed, reflexed, left from intestine. Subventral advulvar setae not seen. Tail short, 32 pm or as long as anal body diameter. Caudal glands not seen.
Differential diagnosis. Onyx mangrovi sp. n. is characterised by having 17-23 supplements with a complex structure: proximally sigmoidal-shaped and distally hook-shaped, and the very short tail with
dorsally curved tip. Onyx mangrovi sp. n. is similar to Onyx cangioensis sp. n. in body shape, amphidial fovea and cephalic setae structure, but differs by having shorter cephalic setae (3 pm in Onyx mangrovi sp. n. vs 5 pm in Onyx cangioenesis sp. n.), shorter spicules (38 pm in Onyx mangrovi sp. n. vs 48.5 pm in Onyx cangioenesis sp. n.), more numerous precloacal supplements (17-23 in Onyx mangrovi sp. n. vs 14-16 in Onyx cangioensis sp. n.), and shorter tail (35 pm in Onyx mangrovi sp. n. vs 68 pm in Onyx cangioenesis sp. n.).
Type material. Holotype, adult male, slide UGMD 104166. Allotype, adult female, slide UGMD 104166, deposited at the Museum of Zoology University Ghent, Belgium. Paratypes. 6$, 5$, slides UGMD 104166 - 70, deposited at the Museum of Zoology University Ghent, Belgium.
Type locality. Can Gio mangrove forest Ho Chi Minh City, Vietnam, subtidal at 0.5 m depth, sediment = silt, sample station CG16 (10°29'196" N and 106°54'994" E).
Etymology: The species name refers to the Cangio mangrove forest where it was found.
Fig. 11. Onyx mangrovi sp. n. A, C, E, G: holotype, A: Head; C: Spicular apparatus; E: Pharynx region; G: Total view; B, D, F: allotype, B: Head; D: Tail region; F: Total view. Scale bars: A- D: 10 pm; E: 30 pm. F- G: 100 pm.
С
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Fig. 12. Onyx mangrovi sp. n. Paratype - male 1: A: end; D: Spicules, proximal ends. Scale bars: A-D: 10 pm.
Identification key to Onyx species
There is only one immature female known of Onyx ferox Ditlevsen, 1921. Therefore, we agree with Blome & Riemann (1994) to regard this species as "species inquirenda", hence we do not include it in this identification key.
1. All supplements in staggered row ..............2
- All supplements uniform and not in staggered row ...................................................4
В
i
D
Amphidial fovea; B: Hollow dorsal tooth; C: Posterior body
2. Male with equally sized supplements
..............................O. orientalis sp. n.
- Male with supplements different in size .....3
3. Male with 18 supplements in 4 different size groups
.......O. adenophorus Blome & Riemann, 1994
- Male with 15 supplements in 3 different size groups.........O. cannoni Blome & Riemann, 1994
4. Male amphidial fovea large, multispiral ......5
Male amphidial fovea with a single loop ......6
5. Amphidial fovea in male with 4-5 turns, broader than the corresponding body diameter, 14
supplements ......O. macramphis Blome & Riemann,
1994
- Amphidial fovea elongated, 2 turns, 10
supplements ................O. dimorphus Gerlach,
1963
- Amphidial fovea elongated, 3 turns, 15 supplements ...............O. paradimorphus sp. n.
- Amphidial fovea atypical: posterior part spiral with 2.5 turns and anterior part hook shaped, 8 supplements .........................O. blomei sp. n.
6. Tail short, less than 1.5 x the anal diameter
..............................O. mangrovi sp. n.
- Tail longer than 2 x the anal diameter ......7
7. Male amphidial fovea a single loop...............8
- Male amphidial fovea elongated-oval, 15 supplements. Female amphidial fovea spiral, 2 turns
...................................O. cobbi sp. n.
8. Male with 7 precloacal supplements
.............O. septempapillatus Wieser, 1954
- Male with 14-16 supplements, cephalic setae short (5 pm, 0.3 x c.b.d.) ..........O. cangioensis sp. n.
- Male with 13 - 17 supplements, cephalic setae long (22 - 28 pm, 0.5 - 1xc.b.d) ...O. perfectus Cobb, 1891
- Male with 22 preanal supplements of atypical structure ..... O. rugatus Wieser, 1959
- Male with 22-24 precloacal supplements
....................O. sagittarius Gerlach, 1950
ACKNOWLEDGEMENT
This study was supported by the Flemish Interuniversity Council (VLIR) and Vietnam National Science Fund 'NAFOSTED'.
REFERENCES
Blome, D. & Riemann, F. 1994. Sandy beach meiofauna of Eastern Australia (Southern Queensland and New
South Wales). III. Revision of the Nematode genus Onyx, Cobb, 1891, with a description of three new species (Nematoda: Desmodoridae). Invertebrate Taxonomy 8: 1483-1492.
COBB, N.A. 1981. Onyx and Dipeltis: new nematode genera with a note on Dorylaimus. Proceeding of the Linnean Society of New South Wales 6: 143 - 158.
Decraemer, W. & Smol, N. 2006. Orders Chromadorida, Desmodorida and Desmoscolecida. In: Freshwater Nematodes: Ecology and Taxonomy (Eyualem Abebe, W. Traunspurger and I. Andrassy. Eds). CABI, pp. 497 - 573.
De Grisse, A.T. 1969. Rédescription ou modifications de quelques téchniques utilisées dans l'etude des nématodes phytoparasitaires. Mededelingen Rijksfaculteit Landbouw Wetenschappen Gent 29: 734-761.
Ditlevsen, J. 1921. Marine free-living nematodes from the Auckland and Campbell Islands. (Paper from Dr. Th. Mortensen's Pacific Expedition 1914-1916. III). Videnskabelige Meddelelser fra Dansk naturhistorisk Forening IKjobenhavn 73: 1-32.
GERLACH, S.A. 1950. Über einige Nematoden aus der Familie der Desmodoriden. In: 'Neue Ergebnisse und Probleme der Zoologie'. (Klatt-Festschrift, Leipzig): 178-198.
Gerlach, S.A. 1956. Die Nematoden besiedlung des tropischen Brandungsstrandes von Pernambuco Brasilianische Meeres-nematoden II. Kieler Meeresforschungen 12: 202-218.
GERLACH, S.A. 1963. Freilebende Meeresnematoden von den Malediven II. Kieler Meeresforschungen 19: 67-103.
RIEMANN, F. 1966. Die interstitielle Fauna im Elbe-Aestuar. Verbreitung und Systematik. Archiv fur Hydrobiologie (Supplement) 31: 1-279.
WIESER, W. 1954. Free-living marine nematodes II. Lunds Universitets Arsskrift (N.F.2) 50: 1-48.
WIESER, W. 1959. Free-living nematodes and other small invertebrates of Puget Sound beaches, Seattle. University of Washington Press. 179 p.
Nguyen Dinh Tu, Nic Smol, Ann Vanreusel, Nguyen Vu Thanh. Шесть новых видов рода Onyx Cobb, 1891 (Nematoda: Desmodoridae) из прибрежных вод Вьетнама.
Резюме. По материалам проб, собранных в 2004-2010 гг. в прибрежных водах Вьетнама, описано шесть новых видов рода Onyx. Onyx cangionensis sp. n. характеризуется наличием 14-16 равновеликих сигмоидальных трубчатых супплементов. Onyx blomei sp. n. отличается половым диморфизмом в строении амфидов: у самцов нетипичная задняя часть амфида спиральная (2.5 завитка), у самок - весь амфид мультиспиральный (2.25 завитка). Onyx orientalis sp. n. характеризуется очень длинными головными щетинками и наличием 18 S-образных трубчатых супплементов у самцов. Половой диморфизм в строении амфидов отмечен и у Onyx cobbi sp. n.: у самцов амфид в виде удлиненной петли, у самок -мультиспиральный. У этого вида 15 слабо S-образных супплементов, причем передний вдвое меньше остальных. Onyx paradimorphus sp. n. отличается мультиспиральным отверстием амфида, загнутыми спикулами, 15 сильно кутикуляризованными S-образными супплементами, и 5 папиллами с щетинкой на уровне спикул. У Onyx mangrovi sp. n. 17-23 супплемента сложной структуры: передняя часть -сигмоидальная, задняя часть - крюковидная. Хвостовой конец тонкий с дорсально загнутым терминусом.
