Three species of monhysterids (nematoda, monhysterida) from mangrove forest of the Me Kong river estuary, Vietnam

31(2): 8-15 Tap chi SINH HOC 6-2009<br /> <br /> <br /> <br /> THREE SPECIES OF MONHYSTERIDS (NEMATODA, MONHYSTERIDA)<br /> FROM MANGROVE FOREST OF THE ME KONG RIVER ESTUARY, VIETNAM<br /> NGUYEN VU THANH<br /> Institute of Ecology and Biological Resources, VAST<br /> VLADIMIR G. GAGARIN<br /> Institute ofltiland Waters Biology of Russian Academy of Sciences, Russia<br /> <br /> ABSTRACT: Three new free-living nematode species of the order Monhysterida from Me Kong river<br /> estuaries of Vietnam are described. Daptonema brevisetosum sp. nov. resembles to Daptonema setosum<br /> (Biitschli, 1874), but differs from it by the relatively shorter outer labial setae, shorter spicules and shorter<br /> cervical and somatic setae. Subsphaerolaimus major sp. nov. similar to Subsphaerolaimus lamasus<br /> (Geriach, 1956), Subsphaerolaimus gerlachi (Wieser, 1959) and Subsphaerolaimus litoralis Lorenzen,<br /> 1978, but differs from them by the longer body, longer spicules and presence of dorso-caudal apophysis<br /> of gubernaculum. Daptonema hirtum (Geriach, 1957) is restored from synonymy of Daptonema setosum<br /> (Biitschli, 1874) and it is raised to range of valid species.<br /> Key words: Free-living nematodes, new species. Me Kong river estuary, mangrove, Vietnam.<br /> <br /> Fauna of free-living brackish water Abbreviation used in the text:<br /> nematodes and marine nematodes of Vietnam is<br /> L. total body length (pm); a. body length<br /> studied recently. At present, this investigating<br /> divided by maximum body width; b. body<br /> field on nematode biodiversity is strongly<br /> length divided by pharengeal length; c. body<br /> improved, in connection with creating of the<br /> length divided by tail length; c'. tail length<br /> new data base for the bio-monitoring<br /> measuring anal or cloacal diameter; V. relation<br /> assessment of water quality in watershed and<br /> of distance from anterior body end to vulva for<br /> wetland ecosystems of whole Vietnam. This<br /> body length at per cent.<br /> work is a part of the Vietnam National Basic<br /> Research on Live Science Program for studying<br /> biodiversity and fauna of free-living aquatic II. DESCRIPTION<br /> nematodes in the mangrove forest of Vietnam<br /> during 2003-2008 years. The nematode samples Family Xyalidae Chitwood, 1951<br /> were collected at the March and April 2004. In 1. Daptonema brevisetosum sp. nov (fig. 1)<br /> this paper, firstly three new species, Daptonema<br /> brevisetosum sp. nov, Subsphaerolaimus major Measurements: table 1. ;L<br /> sp. n. and Daptonema hirtum (Geriach, 1951) Female: Body rather thick and medium size.<br /> are described. Cuticle annulated, comparatively thick.<br /> Thickness of cuticle 4.5-5.5 pm at middle of<br /> I. MATERIAL AND METHODS body. Somatic setae short, rare, 6.5-7.0 pm<br /> long. Anterior body end narrowed. Labial region<br /> Samples are done from a boat using a Polar isolated from the rest of body. Inner labial<br /> grab. In each station one grab is collected with sensillae in shape of small, badly visible<br /> three replicated for nematode analysis. All papillae. Six outer labial and four cephalic<br /> samples are fixed in hot formalin 10%. The sensillae in shape of short setae and united in<br /> nematodes are extracted by LUDOX-TM 50 ahnost one chcle. Its length about 15% of labial<br /> solution with centrifugation method and region width. Amphidial fovea circular and<br /> gradually transferred to anhydrous glycerin and occupying 20-25% of corresponding body<br /> finally mounted into permanent glass slides. diameter. Amphidial fovea situated at distance<br /> 10-11 pm from anterior body end (0.5-0.6 labial Vagina comparatively short, bent to anterior<br /> region width). Stoma small, funnel-shaped. body end. Uterus spacious, contain numerous<br /> Cervical setae present. Oesophagus muscular, small spermatozoa. No postvulval sac. Two or<br /> cylindrical, slightly widened at its posterior end. three small vulval glands present. Vulval<br /> Cardia conical, muscular, surrounded with screscent-shaped, situated posterior to mid-<br /> intestinal tissue. Renette, its canal and excretory body; its lips not cuticularized and not<br /> pore not observed. Rectum length shorter than protruded. Tail slender, elongate-conical,<br /> anal body diameter. gradually narrowing. Caudal setae short and<br /> Female gonad single, anterior, outstretched, rare. Subterminal setae 13-15 pm long. Caudal<br /> situated entirely to the left of the intestine. glands and spinneret well developed.<br /> <br /> <br /> <br /> <br /> Figure 1. Daptonema brevisetosum sp. nov.<br /> A. Entire female; B. Entire male; C. Head of male; D. Head of female;<br /> E. Vulva region; P. Tail of female; G. Tail of male.<br /> <br /> Male: similar to females in general small, badly visible papillae. Labial and<br /> morphology. Cuticle annulated, comparatively cephalic sensillae in shape of short setae and<br /> thick. Somatic setae short, rare. Anterior body united in almost one circle. Its length 15% of<br /> end narrowed. Labial region isolated from the labial region width. Amphidial fovea circular<br /> rest of body. Inner labial sensillae in shape of and occupying 30% of corresponding body<br /> 9<br /> diameter. Amphidial fovea situated at distance Type locality and habitat: Mekong River<br /> 11 pm from anterior body end (0.5 labial region Estuary. Shore line, mangrove. Depth of waters<br /> width). Stoma small, funnel-shaped. Cervical 1.5-4.0 m, fine siU, salinity 18-24%o.<br /> setae present, 6.5 pm long. Oesophagus<br /> Type material: holotype male on slide<br /> muscular, cylinderoid, slightly widened at its<br /> number 44/III and paratypes 3 $ $ deposited at<br /> posterior end. Renette, its canal and excretory<br /> the nematode collection of the Institute of<br /> pore not observed. Testes paired, opposed.<br /> Inland Waters Biology, Borok, Russia.<br /> Anterior testis outstretched, situated to the left<br /> of the intestine; posterior testis reflexed, Differencial diagnosis: the new species<br /> situated to the right of the intestine. Spicules resembles to Daptonema setosum (Bytschli,<br /> comparatively small, archly bent in the distal 1874), but differs from it by having relatively<br /> half, distal end acute, bifurcated. Proximal end shorter outer labial setae (15% vs 50-70% of<br /> cephalated. Spicules 1.3 times as long as cloacal labial region diameter in D. setosum), shorter<br /> body diameter. Gubernaculum comparatively spicules (49 pm long vs 61-64 pm long in D.<br /> massive, with dorso-caudal apophysis. setosum) and shorter cervical and somatic setae<br /> Supplement absent. Tail slender, elongate- (Biitschli, 1874; Bresslau et Sch. Stekhoven,<br /> conical, gradually narrowing. Caudal setae short 1940).<br /> and rare. Subterminal setae 15 pm long. Caudal Etymology: the species name means "with<br /> glands and spinneret well developed.<br /> short setae".<br /> <br /> Table I<br /> Measurements of Daptonema brevisetosum sp. nov. (all measurements in pm, exept ratio)<br /> Paratypes 3 9 $<br /> Characteristics Holotype<br /> Range Mean<br /> 3<br /> L 1140 1247-1286 1262<br /> a 22 18-21 19<br /> b 7.3 7.3-7.8 7.6<br /> c 7.4 6.6-7.1 6.7<br /> c' 3.4 4.3-4.8 4.6<br /> V — 60.0-61.6 61.0<br /> Labial region width 20 20 20<br /> Cephalic setae length 3.0 3.0 3.0<br /> Anterior body end to amphids fovea 11 10-11 11<br /> Oesophagus length 157 161-171 167<br /> Posterior end of oesophagus to vulva ... 596-609 603<br /> Vulva to anus ... 284-333 303<br /> Posterior end of oesophagus to cloaca 829 ... —<br /> Tail length 154 182-196 189<br /> Spicules length (along arch) 49 ... —<br /> <br /> 2. Daptonema hirtum (Geriach, 1951) (fig. 2) region width). Labial region isolated from the<br /> rest of body by the redrawing. Inner labial<br /> Measurements: table 2.<br /> sensillae in shape of minute obscure papillae.<br /> Female: Body rather thick and medium Six outer labial setae and four cephalic setae<br /> size. Cuticle annulated, 3.0-4.0 pm at middle of united in almost one circle. Outer labial setae<br /> body. Somatic setae numerous, long. These slightly longer than cephalic setae and<br /> setae are especially long at the oesophagus occupying 65-80% of labial region width.<br /> region, its length equal 17-22 pm (1.3-1.6 labial Amphidial fovea circular, 4.5-5.0 pm in<br /> <br /> 10<br /> diameter. Anterior margin of amphidial fovea situated entirely to the left of the intestine.<br /> situated 9-15 pm (0.8-1.1 labial region width) Vagina comparatively short, bent to anterior<br /> from anterior body end. Cheilostoma spacious, body end. Uterus spacious, contain small<br /> with sclerotised walls. Esophastoma small, rounded spermatozoa. Short postvulval sac<br /> funnel-shaped, its walls slightiy sclerotised. present. One egg in uterus, in size 70-87 x 31-<br /> Oesophagus slender, cylindroid, slightly 43 pm. Vulva posterior to middle-body,<br /> widened at the posterior end. Cardia cordate, crescent-shaped; its lips not cuticularised and<br /> surrounded with intestinal tissue. Ventral gland, not protruded. Tail slender, with proximal<br /> its canal and excretory pore not observed. conical and distal cylindrical portions gradually<br /> Rectum 0.8-1.0 times as long as anal body going over into one another. Tail tip slightly<br /> diameter. swollen, with subterminal setae. Caudal glands<br /> Female gonad single, anterior, outstretched. and spinneret well developed.<br /> <br /> <br /> <br /> <br /> ilHELcD<br /> <br /> Figure 2. Daptonema hirtum (Geriach, 1951)<br /> A. Entire male; B. Entire female; C. Head of male; D. Head of female;<br /> E. Tail of female; F. Tail of male; G. Vulva region.<br /> <br /> Male: similar to females in general setae present, especially long and dense at the<br /> morphology. Cuticle annulated, thick. Somatic oesophagus region. Labial region isolated from<br /> 11<br /> the rest of body by the redrawing. Inner labial Institute of Ecology and Biological Resources,<br /> sensillae in shape of minute papillae; six outer Vietnam Academy of Science and Technology,<br /> labial and six cephalic sensillae in shape of thin Hanoi, Vietnam.<br /> setae. Amphidial fovea in shape of circle, 6.5- Morphological and taxonomical notes:<br /> 7.5 pm in diameter and situated 8-16 pm from the species Daptonema hirtum was described by<br /> anterior body end. Testes paired, opposed. German nematologist Sebastian A. Geriach from<br /> Anterior testis outstretched, situated to the left the coast of North Sea (Geriach, 1951). Geriach<br /> of the intestine; posterior testis reflexed, indicated, that this new species is very close to<br /> situated to the right of the intestine. Spicules<br /> the species Daptonema setosum (Biitschli, 1874)<br /> comparatively slender, arcuated, distally<br /> and differs from this letter by the shorter body,<br /> bifurcated and proximally widened, with<br /> comparatively longer cephalic setae and shorter<br /> shoulders and knobs. Spicules 1.3-1.5 times as<br /> spicules. Other German nematologist. Sieverst<br /> long as cloacal body diameter. Gubernaculum<br /> Lorenzen found 1969 at the coast of North Sea<br /> comparatively massive, with dorso-caudal<br /> two males of the genus Daptonema (Lorenzen,<br /> apophysis. Precloacal supplements absent. Tail<br /> 1969) too. One male has a body length 1490 pm<br /> slender, gradually narrowing, its posterior<br /> and spicule length 60 pm. Second male has a<br /> portion bended dorsally. Caudal setae present.<br /> Tail tip slightly swollen, with sub-terminal body length 930 pm and spicule length 40 pm.<br /> setae. Caudal glands and spinneret present. Sieverst Lorenzen regarded both these species to<br /> D. setosum and he synonymized the species<br /> Type locality and habitat: Mekong River Daptonema hirtum (Geriach, 1951) with the<br /> Estuary. Shore line, mangrove forest. Depth of species Daptonema setosum (Biitschli, 1874).<br /> water 2.0-4.0 m, fine siU, salinity 18-24%o. We considered that these two males, found by<br /> Material: 10 adult males and 10 adult Sieverst Lorenzen belong to two different<br /> females. 4 SS and 2 9 ? deposited at nematode species. More large species belonged to D.<br /> collection of the Institute of Inland Waters setosum and more less species belonged to D.<br /> Biology, Borok, Russia. 6 SS and 8 9 2 hirtum. Thus, Daptonema hirtum is valid<br /> deposited at the nematode collection of the species ofthe genus Daptonema Cobb, 1920.<br /> <br /> Table 2<br /> Measurements of Daptonema hirtum (Geriach, 1951) (all measurements in pm, except ratio)<br /> <br /> 10 females 10 males<br /> Characteristics<br /> range mean range mean<br /> L 877-1032 953 813-949 881<br /> A 25-31 28 33-40 37<br /> B 3.3-3.9 3.7 3.6-4.1 3.8<br /> c 5.8-7.7 6.4 6.8-8.0 7.3<br /> c' 5.2-7.0 6.4 4.8-6.3 5.7<br /> V 10.3-75.2 73.0 ... ...<br /> Labial region width 15-18 16 14-17 15<br /> Cephalic setae length 10-13 11 9-12 10<br /> Anterior body end to amphids fovea 9-15 12 8-16 12<br /> Oesophagus length 239-291 252 220-256 234<br /> Posterior end of oesophagus to vulva 392-497 435 — ...<br /> Vulva to anus 99-119 109 ... ...<br /> Posterior end of oesophagus to cloaca ... — 490-582 526<br /> Tail length 123-169 149 105-132 121<br /> Spicules length (along arch) ... — 28-30 29<br /> <br /> 12<br /> Family Sphaerolaimidae Filipjev, 1918 Amphidial fovea circular and occupying 35-<br /> 40% of corresponding body diameter.<br /> 1. Subsphaerolaimus major sp. nov (fig. 3) Amphidial fovea situated at distance 13-17 pm<br /> Measurements: table 3. from anterior body end (0.6-0.7 labial region<br /> width). Oesophagus muscular, cylindroid.<br /> Female: no found.<br /> Cardia conical, muscular, surrounded with<br /> Male: Body thick and medium size. Cuticle intestinal tissue. Renetta, its canal and excretory<br /> and subcuticle smooth, without longitudinal pore not observed. Testes paired, opposed.<br /> ridges and transverse striated. Thickness of Anterior testis outstretched, situated to the left<br /> cuticle 1.5-2.0 pm. Somatic setae present. of the intestine. Posterior testis reflexed,<br /> Anterior body end narrowed. Labial region situated to the right intestine. Spicules<br /> slightly flattened, continuing with the body comparatively thin, bended, non-cephalated,<br /> outline. Inner labial sensillae in shape of small, 1.1-1.2 times as long as cloacal body diameter.<br /> badly visible papillae. Outer labial and cephalic Gubernaculum comparatively massive, with<br /> sensillae in shape of short setae and united in dorso-caudal apophysis. Supplements absent.<br /> almost one circle. Its length 38-42% of the Tail slender, elongate-conical, gradually<br /> labial region width. Subcephalic setae arranged narrowing. Caudal setae short and rare. Sub-<br /> in 8 groups, 21-38 pm long. Cheilostoma with terminal setae 16-18 pm long. Caudal glands<br /> ribs; gymnostoma narrow, with sclerotised and spinneret present.<br /> walls; stegostoma small, funnel-shaped.<br /> <br /> <br /> <br /> <br /> 150 nn<br /> 50 nm<br /> 25 nm<br /> <br /> <br /> <br /> <br /> Figure 3. Subsphaerolaimus major sp. nov.<br /> A. Entire male; B. Head of male; C. Tail of male.<br /> 13<br />  Type locality and habitat: Mekong River L =^ 0.96 pm, in S. lutosus 6* L = 0.8 mm, vs S<br /> Estuary, shore line, mangrove. Dept of waters L = 1.03-1.19 mm in new species), longer<br /> 2.0-4.0 m, fine siU, salinity 18-24%o. spicules (in S. lamasus spicules 30 pm long, in<br /> Type material: holotype male on shde S. gerlachi spicules 26 pm long, in S. lutosus<br /> number 34/III deposited at the nematode spicules 28 pm long vs. spicules 46-49 pm long<br /> collection of the Institute of Inland Waters n new species), shorter cephalic setae and<br /> Biology, Borok, Russia. Paratypes 4 SS presence of dorso-caudal apophusis of<br /> deposited at the nematode collection of the gubernaculum (Geriach, 1956; Wieser, 1959;<br /> Institute of Ecology and Biological Resources, Lorenzen, 1978).<br /> Vietnam Academy of Science and Texnology, Etymology: the species name means<br /> Hanoi, Vietnam. "large", "big".<br /> Differential diagnosis: the new species Acknowledgement: The study was partly<br /> morphologically resembles to supported by the Project Impact of mangrove<br /> Subsphaerolaimus lamasus (Geriach, 1956), exploitation of the Benthic ecosystem and the<br /> Subsphaerolaimus gerlachi (Wieser, 1959) and assessment of ecological quality objectives<br /> Subsphaerolaimus litoralis Lorenzen, 1978. It (IMABE) of Belgium. The authors thank the<br /> differs from them by having longer body (in S. financial assistance from VLIP IMABE Project<br /> lamosus (5' L = 0.9 mm, in S. gerlachi S during the period of study.<br /> <br /> Table 3<br /> Measurements of Subsphaerolaimus major sp. nov. (all measurements in pm, except ratia)<br /> Paratypes 4 SS<br /> Characteristics Holotype S<br /> range mean<br /> L 1157 1032-1190 1133<br /> a 21 17-21 19<br /> b 5.7 5.2-5.7 5.5<br /> c 8.2 6.7-8.0 7.4<br /> c' 3.4 3.6-5.2 4.0<br /> Labial region width 22 21-25 23<br /> Cephalic setae length 8.5 8.5-10.0 9.0<br /> Anterior, body end to amphids fovea 14.0 13.0-17.0 15.0<br /> Oesophagus length 204 193-224 207<br /> Posterior end of oesophagus to cloaca 812 679-810 771<br /> Tail length 141 141-176 155<br /> Spicules length (along arch) 47 46-49 48<br /> <br /> <br /> REFERENCES 4. Geriach S. A., 1956: Bohn Inst. Oceanogr.<br /> S. Paulo, 5: 3-69.<br /> Bresslau E., J.H. Schuurmans Stekhoven, 5. Lorenzen S. 1969: Veroff. Inst.<br /> 1940: Bruxelles (Musee Hist. Nat): 1-74. Meeresfosch. Bremerh., Bd., 10: 31-48.<br /> 2. Butschli O., 1874: Abh. Senckend. 6. Lorenzen S., 1978: Zool. Anz., Bd., 200:<br /> Naturforsch. Ges., 9: 239-292. 53-78.<br /> Geriach S. A., 1951: Zool. Jb. (Syst.), Bd. 7. Wieser W., 1959: University of Washington<br /> 80: 379-406. Press.<br /> <br /> <br /> 14<br />  BA LOAI TUYEN TRUNG MOMHYSTERID M6I (NEMATODA,<br /> MONHYSTERIDA) 6 RUNG NGAP MAN CLfA SONG ME CONG, VIET NAM<br /> <br /> NGUYfiN VIJ THANH, VLADIMIR G. GAGARIN<br /> <br /> <br /> TOMTAT<br /> <br /> Md ta ba loai loai tuye'n triing bien sdng tu do thudc bp Monhysterida tai rimg ngSp man d ciia sdng<br /> Me Cdng, Viet Nam.<br /> Loai mdi Daptonema brevisetosum sp. nov. ve hinh thai hpc tUOng dd'i gidng loai Daptonema setosum<br /> (Butschli, 1874), song khac biet vdi loai tren bdi cd cac ldng ciing vong ngoai cung tren dau ngan hon (15% so<br /> vdi 50-70% chi6u rpng viing mdi d D. setosum), gai sinh due cung ngan hon (49 pm so vdi 61-64 pm d loai<br /> D. setosum), ngoai ra cdn khac biet bdi cac long dinh duong va long viing cd cung ngan hOn.<br /> Loai mdi Subsphaerolaimus major sp. nov. tuong ddi gid'ng vdi loai Subsphaerolaimus lamasus (Geriach,<br /> 1956), Subsphaerolaimus gerlachi (Wieser, 1959) va Subsphaerolaimus litoralis Lorenzen, 1978, song khac<br /> biet vdi cac loai ndi tren bdi cd co the dai hon (L = 1,03-1,19 mm, so vdi S. lamosus L = 0,9 mm;-.?, gerlachi<br /> L = 0,96 pm va d S. lutosus L = 0,8 mm); gai sinh due dai hon (d loai mdi gai sinh due 46-49 pm; d 3 loai<br /> tren, gai sinh due = 26-30 pm); ngoai ra loai mdi con cd the nhan bie't bdi bdi hinh dang khac biet ciia mieng<br /> dem ciia trp gai sinh due, nam gan vudng gdc ve phia ben lung ciia dudi.<br /> Loai mdi Daptonema hirtum dupc nha khoa hpc Diic Sebastian Geriach da md ta nam 1951 dua tren miu<br /> vat ma dng thu dupc tut Bien Bac, dng nhan xet rang loai mdi Daptonema hirtum ve hinh thai hpc, tUOng ddi<br /> gidng vdi loai da bie't trong gio'ng Daptonema la loai D. setosum Butschli, 1874, song khac biet bdi kich thudc<br /> CO the nhd hon, ldng ciing tren ddu dai hon va gai sinh due ngdn hon. Nam 1969, cung tii mlu vat Bien Bac<br /> nha tuye'n triing hpc ngudi Due Sieverst Lorenzen da gap 2 con due ciia gidng Daptonema, mdt con cd kich<br /> thudc ldn (L = 1490 pm; gai sinh due = 60 pm) va con thii hai nhd hon (930 pm; gai sinh due = 40 pm), sau<br /> khi xem xet dng da synonym hai loai Daptonema setosum (Butschli, 1874) va loai Daptonema hirtum<br /> (Geriach, 1951) thanh loai Daptonema setosum (Butschli, 1874).<br /> Dua vao cac sd do tit mlu vat Viet Nam cho thay, loai Daptonema hirtum la loai hien hiru (valid species),<br /> va hai loai D. Hirstum va loai D. Setosun la hai loai hoan toan khac nhau.<br /> <br /> <br /> Ngdy nhan bdi: 4-3-2008<br /> <br /> <br /> <br /> <br /> 15<br />