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31(2): 8-15 6-2009 Tap chi SINH HOC THREE SPECIES OF MONHYSTERIDS (NEMATODA, MONHYSTERIDA) FROM MANGROVE FOREST OF THE ME KONG RIVER ESTUARY, VIETNAM NGUYEN VU THANH Institute of Ecology and Biological Resources, VAST VLADIMIR G. GAGARIN Institute ofltiland Waters Biology of Russian Academy of Sciences, Russia ABSTRACT: Three new free-living nematode species of the order Monhysterida from Me Kong river estuaries of Vietnam are described. Daptonema brevisetosum sp. nov. resembles to Daptonema setosum (Biitschli, 1874), but differs from it by the relatively shorter outer labial setae, shorter spicules and shorter cervical and somatic setae. Subsphaerolaimus major sp. nov. similar to Subsphaerolaimus lamasus (Geriach, 1956), Subsphaerolaimus gerlachi (Wieser, 1959) and Subsphaerolaimus litoralis Lorenzen, 1978, but differs from them by the longer body, longer spicules and presence of dorso-caudal apophysis of gubernaculum. Daptonema hirtum (Geriach, 1957) is restored from synonymy of Daptonema setosum (Biitschli, 1874) and it is raised to range of valid species. Key words: Free-living nematodes, new species. Me Kong river estuary, mangrove, Vietnam. Fauna of free-living brackish water nematodes and marine nematodes of Vietnam is studied recently. At present, this investigating field on nematode biodiversity is strongly improved, in connection with creating of the new data base for the bio-monitoring assessment of water quality in watershed and wetland ecosystems of whole Vietnam. This work is a part of the Vietnam National Basic Research on Live Science Program for studying biodiversity and fauna of free-living aquatic nematodes in the mangrove forest of Vietnam during 2003-2008 years. The nematode samples were collected at the March and April 2004. In this paper, firstly three new species, Daptonema brevisetosum sp. nov, Subsphaerolaimus major sp. n. and Daptonema hirtum (Geriach, 1951) are described. I. MATERIAL AND METHODS Samples are done from a boat using a Polar grab. In each station one grab is collected with three replicated for nematode analysis. All samples are fixed in hot formalin 10%. The nematodes are extracted by LUDOX-TM 50 solution with centrifugation method and gradually transferred to anhydrous glycerin and finally mounted into permanent glass slides. Abbreviation used in the text: L. total body length (pm); a. body length divided by maximum body width; b. body length divided by pharengeal length; c. body length divided by tail length; c'. tail length measuring anal or cloacal diameter; V. relation of distance from anterior body end to vulva for body length at per cent. II. DESCRIPTION Family Xyalidae Chitwood, 1951 1. Daptonema brevisetosum sp. nov (fig. 1) Measurements: table 1. ;L Female: Body rather thick and medium size. Cuticle annulated, comparatively thick. Thickness of cuticle 4.5-5.5 pm at middle of body. Somatic setae short, rare, 6.5-7.0 pm long. Anterior body end narrowed. Labial region isolated from the rest of body. Inner labial sensillae in shape of small, badly visible papillae. Six outer labial and four cephalic sensillae in shape of short setae and united in ahnost one chcle. Its length about 15% of labial region width. Amphidial fovea circular and occupying 20-25% of corresponding body diameter. Amphidial fovea situated at distance 10-11 pm from anterior body end (0.5-0.6 labial region width). Stoma small, funnel-shaped. Cervical setae present. Oesophagus muscular, cylindrical, slightly widened at its posterior end. Cardia conical, muscular, surrounded with intestinal tissue. Renette, its canal and excretory pore not observed. Rectum length shorter than anal body diameter. Female gonad single, anterior, outstretched, situated entirely to the left of the intestine. Vagina comparatively short, bent to anterior body end. Uterus spacious, contain numerous small spermatozoa. No postvulval sac. Two or three small vulval glands present. Vulval screscent-shaped, situated posterior to midbody; its lips not cuticularized and not protruded. Tail slender, elongate-conical, gradually narrowing. Caudal setae short and rare. Subterminal setae 13-15 pm long. Caudal glands and spinneret well developed. Figure 1. Daptonema brevisetosum sp. nov. A. Entire female; B. Entire male; C. Head of male; D. Head of female; E. Vulva region; P. Tail of female; G. Tail of male. Male: similar to females in general morphology. Cuticle annulated, comparatively thick. Somatic setae short, rare. Anterior body end narrowed. Labial region isolated from the rest of body. Inner labial sensillae in shape of small, badly visible papillae. Labial and cephalic sensillae in shape of short setae and united in almost one circle. Its length 15% of labial region width. Amphidial fovea circular and occupying 30% of corresponding body 9 diameter. Amphidial fovea situated at distance 11 pm from anterior body end (0.5 labial region width). Stoma small, funnel-shaped. Cervical setae present, 6.5 pm long. Oesophagus muscular, cylinderoid, slightly widened at its posterior end. Renette, its canal and excretory pore not observed. Testes paired, opposed. Anterior testis outstretched, situated to the left of the intestine; posterior testis reflexed, situated to the right of the intestine. Spicules comparatively small, archly bent in the distal half, distal end acute, bifurcated. Proximal end cephalated. Spicules 1.3 times as long as cloacal body diameter. Gubernaculum comparatively massive, with dorso-caudal apophysis. Supplement absent. Tail slender, elongateconical, gradually narrowing. Caudal setae short and rare. Subterminal setae 15 pm long. Caudal glands and spinneret well developed. Type locality and habitat: Mekong River Estuary. Shore line, mangrove. Depth of waters 1.5-4.0 m, fine siU, salinity 18-24%o. Type material: holotype male on slide number 44/III and paratypes 3 $ $ deposited at the nematode collection of the Institute of Inland Waters Biology, Borok, Russia. Differencial diagnosis: the new species resembles to Daptonema setosum (Bytschli, 1874), but differs from it by having relatively shorter outer labial setae (15% vs 50-70% of labial region diameter in D. setosum), shorter spicules (49 pm long vs 61-64 pm long in D. setosum) and shorter cervical and somatic setae (Biitschli, 1874; Bresslau et Sch. Stekhoven, 1940). Etymology: the species name means "with short setae". Table I Measurements of Daptonema brevisetosum sp. nov. (all measurements in pm, exept ratio) Paratypes 3 9 $ Characteristics Holotype 3 L a b c c' V Labial region width Cephalic setae length Anterior body end to amphids fovea Oesophagus length Posterior end of oesophagus to vulva Vulva to anus Posterior end of oesophagus to cloaca Tail length Spicules length (along arch) 1140 22 7.3 7.4 3.4 — 20 3.0 11 157 ... ... 829 154 49 2. Daptonema hirtum (Geriach, 1951) (fig. 2) Measurements: table 2. Female: Body rather thick and medium size. Cuticle annulated, 3.0-4.0 pm at middle of body. Somatic setae numerous, long. These setae are especially long at the oesophagus region, its length equal 17-22 pm (1.3-1.6 labial 10 Range Mean 1247-1286 18-21 7.3-7.8 6.6-7.1 4.3-4.8 60.0-61.6 20 3.0 10-11 161-171 596-609 284-333 ... 182-196 ... 1262 19 7.6 6.7 4.6 61.0 20 3.0 11 167 603 303 — 189 — region width). Labial region isolated from the rest of body by the redrawing. Inner labial sensillae in shape of minute obscure papillae. Six outer labial setae and four cephalic setae united in almost one circle. Outer labial setae slightly longer than cephalic setae and occupying 65-80% of labial region width. Amphidial fovea circular, 4.5-5.0 pm in diameter. Anterior margin of amphidial fovea situated 9-15 pm (0.8-1.1 labial region width) from anterior body end. Cheilostoma spacious, with sclerotised walls. Esophastoma small, funnel-shaped, its walls slightiy sclerotised. Oesophagus slender, cylindroid, slightly widened at the posterior end. Cardia cordate, surrounded with intestinal tissue. Ventral gland, its canal and excretory pore not observed. Rectum 0.8-1.0 times as long as anal body diameter. Female gonad single, anterior, outstretched. situated entirely to the left of the intestine. Vagina comparatively short, bent to anterior body end. Uterus spacious, contain small rounded spermatozoa. Short postvulval sac present. One egg in uterus, in size 70-87 x 3143 pm. Vulva posterior to middle-body, crescent-shaped; its lips not cuticularised and not protruded. Tail slender, with proximal conical and distal cylindrical portions gradually going over into one another. Tail tip slightly swollen, with subterminal setae. Caudal glands and spinneret well developed. ilHELcD Figure 2. Daptonema hirtum (Geriach, 1951) A. Entire male; B. Entire female; C. Head of male; D. Head of female; E. Tail of female; F. Tail of male; G. Vulva region. Male: similar to females in general morphology. Cuticle annulated, thick. Somatic setae present, especially long and dense at the oesophagus region. Labial region isolated from 11 the rest of body by the redrawing. Inner labial sensillae in shape of minute papillae; six outer labial and six cephalic sensillae in shape of thin setae. Amphidial fovea in shape of circle, 6.57.5 pm in diameter and situated 8-16 pm from anterior body end. Testes paired, opposed. Anterior testis outstretched, situated to the left of the intestine; posterior testis reflexed, situated to the right of the intestine. Spicules comparatively slender, arcuated, distally bifurcated and proximally widened, with shoulders and knobs. Spicules 1.3-1.5 times as long as cloacal body diameter. Gubernaculum comparatively massive, with dorso-caudal apophysis. Precloacal supplements absent. Tail slender, gradually narrowing, its posterior portion bended dorsally. Caudal setae present. Tail tip slightly swollen, with sub-terminal setae. Caudal glands and spinneret present. Type locality and habitat: Mekong River Estuary. Shore line, mangrove forest. Depth of water 2.0-4.0 m, fine siU, salinity 18-24%o. Material: 10 adult males and 10 adult females. 4 SS and 2 9 ? deposited at nematode collection of the Institute of Inland Waters Biology, Borok, Russia. 6 SS and 8 9 2 deposited at the nematode collection of the Institute of Ecology and Biological Resources, Vietnam Academy of Science and Technology, Hanoi, Vietnam. Morphological and taxonomical notes: the species Daptonema hirtum was described by German nematologist Sebastian A. Geriach from the coast of North Sea (Geriach, 1951). Geriach indicated, that this new species is very close to the species Daptonema setosum (Biitschli, 1874) and differs from this letter by the shorter body, comparatively longer cephalic setae and shorter spicules. Other German nematologist. Sieverst Lorenzen found 1969 at the coast of North Sea two males of the genus Daptonema (Lorenzen, 1969) too. One male has a body length 1490 pm and spicule length 60 pm. Second male has a body length 930 pm and spicule length 40 pm. Sieverst Lorenzen regarded both these species to D. setosum and he synonymized the species Daptonema hirtum (Geriach, 1951) with the species Daptonema setosum (Biitschli, 1874). We considered that these two males, found by Sieverst Lorenzen belong to two different species. More large species belonged to D. setosum and more less species belonged to D. hirtum. Thus, Daptonema hirtum is valid species ofthe genus Daptonema Cobb, 1920. Table 2 Measurements of Daptonema hirtum (Geriach, 1951) (all measurements in pm, except ratio) Characteristics L A B c c' V Labial region width Cephalic setae length Anterior body end to amphids fovea Oesophagus length Posterior end of oesophagus to vulva Vulva to anus Posterior end of oesophagus to cloaca Tail length Spicules length (along arch) 12 10 females range 877-1032 25-31 3.3-3.9 5.8-7.7 5.2-7.0 10.3-75.2 15-18 10-13 9-15 239-291 392-497 99-119 ... 123-169 ... mean 953 28 3.7 6.4 6.4 73.0 16 11 12 252 435 109 — 149 — 10 males range 813-949 33-40 3.6-4.1 6.8-8.0 4.8-6.3 ... 14-17 9-12 8-16 220-256 — ... 490-582 105-132 28-30 mean 881 37 3.8 7.3 5.7 ... 15 10 12 234 ... ... 526 121 29 Family Sphaerolaimidae Filipjev, 1918 1. Subsphaerolaimus major sp. nov (fig. 3) Measurements: table 3. Female: no found. Male: Body thick and medium size. Cuticle and subcuticle smooth, without longitudinal ridges and transverse striated. Thickness of cuticle 1.5-2.0 pm. Somatic setae present. Anterior body end narrowed. Labial region slightly flattened, continuing with the body outline. Inner labial sensillae in shape of small, badly visible papillae. Outer labial and cephalic sensillae in shape of short setae and united in almost one circle. Its length 38-42% of the labial region width. Subcephalic setae arranged in 8 groups, 21-38 pm long. Cheilostoma with ribs; gymnostoma narrow, with sclerotised walls; stegostoma small, funnel-shaped. Amphidial fovea circular and occupying 3540% of corresponding body diameter. Amphidial fovea situated at distance 13-17 pm from anterior body end (0.6-0.7 labial region width). Oesophagus muscular, cylindroid. Cardia conical, muscular, surrounded with intestinal tissue. Renetta, its canal and excretory pore not observed. Testes paired, opposed. Anterior testis outstretched, situated to the left of the intestine. Posterior testis reflexed, situated to the right intestine. Spicules comparatively thin, bended, non-cephalated, 1.1-1.2 times as long as cloacal body diameter. Gubernaculum comparatively massive, with dorso-caudal apophysis. Supplements absent. Tail slender, elongate-conical, gradually narrowing. Caudal setae short and rare. Subterminal setae 16-18 pm long. Caudal glands and spinneret present. 150 nn 50 nm 25 nm Figure 3. Subsphaerolaimus major sp. nov. A. Entire male; B. Head of male; C. Tail of male. 13 Type locality and habitat: Mekong River Estuary, shore line, mangrove. Dept of waters 2.0-4.0 m, fine siU, salinity 18-24%o. Type material: holotype male on shde number 34/III deposited at the nematode collection of the Institute of Inland Waters Biology, Borok, Russia. Paratypes 4 SS deposited at the nematode collection of the Institute of Ecology and Biological Resources, Vietnam Academy of Science and Texnology, Hanoi, Vietnam. Differential diagnosis: the new species morphologically resembles to Subsphaerolaimus lamasus (Geriach, 1956), Subsphaerolaimus gerlachi (Wieser, 1959) and Subsphaerolaimus litoralis Lorenzen, 1978. It differs from them by having longer body (in S. lamosus (5' L = 0.9 mm, in S. gerlachi S L =^ 0.96 pm, in S. lutosus 6* L = 0.8 mm, vs S L = 1.03-1.19 mm in new species), longer spicules (in S. lamasus spicules 30 pm long, in S. gerlachi spicules 26 pm long, in S. lutosus spicules 28 pm long vs. spicules 46-49 pm long n new species), shorter cephalic setae and presence of dorso-caudal apophusis of gubernaculum (Geriach, 1956; Wieser, 1959; Lorenzen, 1978). Etymology: "large", "big". the species name means Acknowledgement: The study was partly supported by the Project Impact of mangrove exploitation of the Benthic ecosystem and the assessment of ecological quality objectives (IMABE) of Belgium. The authors thank the financial assistance from VLIP IMABE Project during the period of study. Table 3 Measurements of Subsphaerolaimus major sp. nov. (all measurements in pm, except ratia) Characteristics Holotype S L a b c c' Labial region width Cephalic setae length Anterior, body end to amphids fovea Oesophagus length Posterior end of oesophagus to cloaca Tail length Spicules length (along arch) 4. Geriach S. A., 1956: Bohn Inst. Oceanogr. S. Paulo, 5: 3-69. REFERENCES Bresslau E., J.H. Schuurmans Stekhoven, 1940: Bruxelles (Musee Hist. Nat): 1-74. 2. Butschli O., 1874: Abh. Naturforsch. Ges., 9: 239-292. Senckend. Geriach S. A., 1951: Zool. Jb. (Syst.), Bd. 80: 379-406. 14 1157 21 5.7 8.2 3.4 22 8.5 14.0 204 812 141 47 Paratypes 4 SS mean range 1133 1032-1190 19 17-21 5.2-5.7 5.5 6.7-8.0 7.4 3.6-5.2 4.0 21-25 23 8.5-10.0 9.0 13.0-17.0 15.0 193-224 207 679-810 771 141-176 155 46-49 48 5. Lorenzen S. 1969: Veroff. Inst. Meeresfosch. Bremerh., Bd., 10: 31-48. 6. Lorenzen S., 1978: Zool. Anz., Bd., 200: 53-78. 7. Wieser W., 1959: University of Washington Press. BA LOAI TUYEN TRUNG MOMHYSTERID M6I (NEMATODA, MONHYSTERIDA) 6 RUNG NGAP MAN CLfA SONG ME CONG, VIET NAM NGUYfiN VIJ THANH, VLADIMIR G. GAGARIN TOMTAT Md ta ba loai loai tuye'n triing bien sdng tu do thudc bp Monhysterida tai rimg ngSp man d ciia sdng Me Cdng, Viet Nam. Loai mdi Daptonema brevisetosum sp. nov. ve hinh thai hpc tUOng dd'i gidng loai Daptonema setosum (Butschli, 1874), song khac biet vdi loai tren bdi cd cac ldng ciing vong ngoai cung tren dau ngan hon (15% so 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 D. setosum), ngoai ra cdn khac biet bdi cac long dinh duong va long viing cd cung ngan hOn. Loai mdi Subsphaerolaimus major sp. nov. tuong ddi gid'ng vdi loai Subsphaerolaimus lamasus (Geriach, 1956), Subsphaerolaimus gerlachi (Wieser, 1959) va Subsphaerolaimus litoralis Lorenzen, 1978, song khac 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 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 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 dem ciia trp gai sinh due, nam gan vudng gdc ve phia ben lung ciia dudi. Loai mdi Daptonema hirtum dupc nha khoa hpc Diic Sebastian Geriach da md ta nam 1951 dua tren miu vat ma dng thu dupc tut Bien Bac, dng nhan xet rang loai mdi Daptonema hirtum ve hinh thai hpc, tUOng ddi gidng vdi loai da bie't trong gio'ng Daptonema la loai D. setosum Butschli, 1874, song khac biet bdi kich thudc CO the nhd hon, ldng ciing tren ddu dai hon va gai sinh due ngdn hon. Nam 1969, cung tii mlu vat Bien Bac nha tuye'n triing hpc ngudi Due Sieverst Lorenzen da gap 2 con due ciia gidng Daptonema, mdt con cd kich thudc ldn (L = 1490 pm; gai sinh due = 60 pm) va con thii hai nhd hon (930 pm; gai sinh due = 40 pm), sau khi xem xet dng da synonym hai loai Daptonema setosum (Butschli, 1874) va loai Daptonema hirtum (Geriach, 1951) thanh loai Daptonema setosum (Butschli, 1874). Dua vao cac sd do tit mlu vat Viet Nam cho thay, loai Daptonema hirtum la loai hien hiru (valid species), va hai loai D. Hirstum va loai D. Setosun la hai loai hoan toan khac nhau. Ngdy nhan bdi: 4-3-2008 15