Fauna of marine nematodes from the intertidal of Putyatin Island (Sea of Japan, Peter the Great Bay)

Ludmila S. BELOGUROVA

Institute of Marine Biology FEB RAS, Vladivostok, 690041, Russia

Twenty-two species of free-living nematodes belonging to 18 genera, 10 families and 5 orders, have been found in the intertidal zone of Putyatin Island (Sea of Japan, Peter the Great Bay). The order Enoplida is represented by 14 species, the order Monhysterida by 3 species; the orders Chromadorida and Areolaimida by two species, and the order Desmodorida by one species. The genus Eurystomina is represented by 3 species; the two genera, Adoncholaimus and Axonolaimus, by two species. Only one species was recorded for each of the genera: Phanoderma, Enoplus, Anticoma, Pontonema, Viscosia, Oncholaimium, Oncholaimus, Pseudoncholaimus, Calyptronema, Sabatieria, Paracanthonchus, Monoposthia, Pseudosteineria, Mesotheristus, Terschellingia. Twenty one species of nematodes were found in the lower intertidal horizon in the belt-forming communities of Phyllospadix iwatensis, Sargassum miyabei, Corallina pululifera, that is 95.4% of the total number of nematodes. Nine species were found in muddy sand within the belt-forming communities of Phyllospadix iwatensis. They are: Anticoma behringiana, Adoncholaimus fuscus, Viscosia stenostoma, Eurystomina ophtalmophora, Sabatieria palmaris, Pseudosteineria inaequispiculata, Mesotheristus paracircumscriptus, Terschellingia glabricutis, and Axonolaimus orus. Twelve species were recorded in the middle intertidal horizon in the belt–forming communities of Chaetomorpha moniligera, Enteromorpha clathrata, Scytociphon lomentaria. The nematode fauna of this horizon is represented by the species, which are also found in the lower intertidal horizon, with the exception of one species, Oncholaimium japonicum, recorded only in the middle intertidal horizon in the belt-forming Chaetomorpha moniligera. Four species of nematodes (Enoplus anisospiculis, Pontonema papilliferum, Oncholaimus brachycercus, Monoposthia costata) were found in the high intertidal horizon. These species inhabited both the middle and the lower intertidal horizons.

Estimation of taxonomic biodiversity of freeliving nematodes in the Russian Arctic Seas

Valentina V.GALTSOVA, L.V. KULANGIEVA

Zoological Institute Russian Academy of Sciences, St.Petersburg, gvv@eti.mail.iephb.nw.ru

Studies on biodiversity estimation frequently encounter the difficulties connected with the differences to the degree in the completeness of the mastery of fauna. The methods that make it possible at least approximately to estimate the degree of the completeness of the taxonomic mastery of concrete regions practically do not exist. There is a common property of the regular distribution of any units or their characteristics under the conditions of the limited space: their sequences form straight line with logarithmic scale of both axes. The concrete region which biodiversity of fauna is in prospect to estimate is such limited space. The numerical ratio of taxa of different ranks also forms the sequence which approaches logarithmic. If we build the graph on the Y-axis of which the logarithms of the number of taxa of this rank are arranged and on the X-axis - order, family, genus, species arranged through the logarithmically diminishing intervals then this graph for the concrete region of the World Ocean will be represented by straight line when the group is sufficiently well studied systematically. At the same time the groups weakly studied systematically do not give this rectilinear graph. Thus the possibility to build graph according to the known number of high taxa and according to this graph appears to estimate the number of taxa of genus and species ranks. Then, after comparing the obtained values with the known facts it is easy to estimate the degree of the completeness of mastery. We have accomplished a similar work for several groups of invertebrates from the Arctic seas of Russia. Most fully studied groups proved to be bivalve molluscs (70%), by least studied - nematodes (28, 5%), whose list at the present time includes 376 species. According to our estimation the assumed number of the nematode species in this region is not less than 1300, i.e. the presence of 1000 extra species of nematodes should be expected.

Nematodes of the family Cyatholaimidae from the Russian coast of the Sea of Japan

Olga I. DASHCHENKO

Far-East State University, Vladivostok, 690600, Russia, dashcha@bio.dvgu.ru

The family Cyatholaimidae consists of four subfamilies, which are well distinguished by the cuticle ornamentation and by the shape of the male supplements. Five cyatholaimid species have been registered in the Peter the Great Bay of the Sea of Japan. These nematodes inhabit the silty sand, and only Acanthonchus tridentatus has been found in the biofoulings of concrete plates. Three species: Acanthonchus tridentatus Kito, 1976; Paracanthonchus macrodon Ditlevsen, 1918; Paracyatholaimus pugettensis Wieser and Hopper, 1967, belong to the subfamily Paracanthonchinae. The males of these species have the tubiform supplements. The new species, Marilynia maritima sp.n. (subfam. Cyatholaiminae), has five weakly cuticularized goblet-shaped supplements (not always clear). The supplement has intermediate shape between tubiform and goblet-shaped. The second new species, Pomponema gracilis sp.n. (subfam. Pomponematinae), has 15-19 sucker-shaped supplements. The cuticle forms large wrinkles between supplements.

Four species of marine nematodes of the order Desmodorida from the Far Eastern sea

Vladimir V. MORDUCHOVICH*, Natalia P. FADEEVA**

Far East State University, Vladivostok, 690600, Russia, *vvmora@mail.ru, **nfadeeva@mail.primorye.ru

Marine nematodes of the order Desmodorida are rare and poorly studied group. Four species of desmodorids were described from the Sea of Japan and the Okhotsk Sea. Paramicrolaimus spirulifer Wieser, 1959 is recorded in the Far East seas for the first time. In general aspects (cephalic setae of second and third circle are slender, asymmetrical stoma, oval amphids, number of supplements) males and females agree with the descriptions of this species by Wieser (1959) and Jensen (1978). Female reproductive system is described. Aponema minuta sp. n. is the smallest Aponema species known with a body length less than 500 μm, bent spicules 18 μm around the arc, 20-21 μm from tip to tip, and gubernaculum with sclerotized dorsocaudally directed apophyses. Microlaimus adrianovi sp.n. can also be easily distinquished from all known congeneric species in having transverse slit-like vulva with strong sclerotized margins. Molgolaimus orientalis sp.n. differs from all other molgolaimids by the shape and size of spicules and specific rose-coloured inclusions in the cuticle. The photomicrographs of the species of nematodes by light microsopy are presented with detailed morphological descriptions.

Fauna of free living nematodes from some water bodies in the North of Vietnam

Vu Thanh NGUYEN¹, Vladimir N. GAGARIN²

¹Department of Nematology, Institute of Ecology and Biological Resources, Vietnam National Center for Natural Sciences and Technology (NCST), Hanoi, Vietnam

²Institute of Inland Waters Biology, Russian Academy of Sciences, Borok, Yaroslavl Prov., Russia

Long time the fauna of free-living aquatic nematodes, including fauna of freshwater and brackish water nematodes and marine nematodes of Vietnam has not been studied. At present, the intensity of investigation of fauna of free-living nematodes in Vietnam water bodies is strongly improved, in connection with creating of the new database for the biological monitoring assessment of water quality from surface watercourse of all river watersheds and the wetland ecosystems of Vietnam. In 2000-2002 nematode fauna from 4 water ecosystems of Nhue River, To Lich River, Cau River and West Lake in Northern Vietnam has been observed and studied. These three rivers are situated not far from Hanoi territory. The Cau River flows through Bac Giang province, Thai Nguyen province, Bac Kan province. Fourteen samples were collected from Nhue River and fourteen from To Lich River, fifteen samples were collected from West Lake and twenty eight samples were also collected from Cau River. All nematode samples were taken at the distance of 1-3 m from the bank (shore) at the depth of 1-2 m with ground-slit sediment. The samples were taken by boat by Ponar grabs (core sampler). Nematode samples were fixed by hot TAF solution, and processed to pure glycerin by a slow evaporation Seinhorst’s method and mounted on permanent glass slides. All 89 species belonging to ten orders were found in the samples from four water bodies, 10 species were described and identified as new for science. Most of the species (29) belong to the order Tylenchida, 19 species belong to the order Dorylaimida. All species could be divided into three ecological groups: (i) fresh-water forms, (ii) saline-water forms and (iii) terrestrial forms. The latter group predominates and is the most numerous - 59 species. The scantiest group is saline-water form - 7 species. 23 another nematode species are fresh-water forms.

The Euchromadora–Parapinnanema complex

Nic SMOL^1*, Verônica da FONSÊCA- GENEVOIS², Tânia Campinas Bezerra^1**, Alessandra Prates BOTELHO⁴, Maria A. FRANCO³

¹PINC, Vakgroep Biologie, Universiteit Gent, Gent, Belgium, nic.smol@UGent.be, tanianara@hotmail.com

²Departmento de Zoologia, Universidade Federal de Pernambuco, Cidade Universitária, Recife-PE, Brasil, meiofaunabrasil@hotmail.com

³Mariene Biologie, Vakgroep Biologie, Gent, Belgium, assuncaofranco@hotmail.com

The discovery of new Euchromadora–Parapinnanema–like species from Brazil posed problems of generic placement. Careful examination of the species of both genera resulted in re-evaluation of the generic characters. The presence of a precloacal raised cuticle in the males can no longer be considered as a distinguishing character between Euchromadora and Parapinnanema, as it occurs in both genera. The degree of sclerotisation of the onchial cavity and the structure of the female reproductive system remain valid characters in differentiating of both genera: in Euchromadora rows of denticles are present in the onchial cavity whereas in  Parapinnanema they are absent. Females of Parapinnanema are characterized by having a longitudinal vulva and a strong double sphincter around the uterine chamber, whereas Euchromadora has a transverse vulva and no double sphincter.

© Russian Society of Nematologists, Institute of Marine Biology FEB RAS, 2002