On some predatory nematodes from the Okavango Delta,Botswana

Five species of Mononchida and Mononchulus nodicaudatus (v. Daday, 1899) Cobb, 1918 are reported from freshwater sediments at or near Boba Island, Okavango Swamps, Botswana. Illustrations are given for Mylonchulus lacustris (Cobb N.A. in Cobb MX, 1915) Andrássy, 1958, Iotonchus risoceiae (Carvalho, 1955) Andrássy, 1958 and Cobbonchus spec. Two species of Mononchus Bastian, 1865, M. aquaticus Coetzee, 1968 and M. truncatus Bastian, 1865 were also found. The usually rare species M. nodicaudatus was well represented and its juvenile stages are described for the first time.     

Two new and three redescribed species of Viscosia (Nematoda,Oncholaimidae)

Viscosia coomansi sp. nov. and Viscosia heterolaina sp. nov. are described from Lake Grevelingen and Eastern Scheldt (The Netherlands). Viscosia glabra (Bastian, 1865) de Man 1890, Viscosia franzii Boucher 1977, and Viscosia viscosa (Bastian 1865) de Man 1890 are redescribed, taking into account new important characters. Juvenile specimens are depicted for V. viscosa. Viscosia carnleyensis Ditlevsen, 1921 is synonymized with Viscosia glabra (Bastian, 1865). Mononcholaimus viscosus Allgén, 1930 and Mononcholaimus elegans sensu Schuurmans-Stekhoven, 1942, 1950 (nec. Kreis, 1924) are synonymized with Viscosia viscosa (Bastian, 1865).     

Aquatic nematodes from Ethiopia III

Six species of the genus Eumonhystera, one of which is new to science, are described from bottom samples of Lake Tana and two associated rivers, River Abbay and R. Gelda, Ethiopia. E. geraerti n.sp. can be identified by being the only species in the genus that combines very posteriorly positioned vulva [V% = 68.2 ± 0.7 (67.3–69.3)] with very anteriorly positioned amphids (Amph-ABE/LRW = 0.8). The other five species encountered, E. dispar (Bastian, 1865) Andrássy, 1981, E. filiformis (Bastian, 1865) Andrássy, 1981, E. pseudobulbosa (von Daday, 1896) Andrássy, 1981, E. mwerazii (Meyl, 1957) Andrássy, 1981, and E. vulgaris (de Man, 1880), Andrássy, 1981, are described in detail. The identities of some of the already described populations of E. dispar, E. filiformis and E. vulgaris are questioned and clearer and better ways of defining each of these three species are suggested. A peritrophic-like membrane on the outer side of the brush-border of the intestine of E. mwerazii, a species reported here for the first time out of its type locality, is reported. Also, scanning electronmicrographs of sectioned and entire specimens of E. mwerazii are presented. All species are reported from Ethiopia for the first time.     

On the Identity and Nomenclature of Paracanthonchus caecus (Bastian, 1865), with a Redefinition of the Genus Paracanthonchus Micoletzky (Nematoda, Cyatholaimidae)

A historical review of the systematics of Paracanthonchus caecus (Bastian, 1865) and a comparison of specimens from different localities show that this "species" in fact comprises four distinct species. Paracanthonchus caecus Micoletzky, 1924 nec P. caecus (Bastian, 1865) is designated as the valid type species of the genus Paracanthonchus. P. heterodontus (Schulz, 1932) and P. thaumasius (Schulz, 1932) are re-established. P. caecm sensu Gerlach 1965 is considered as a distinct species: P. gerlachi sp.n. P. canadensis sp.n. is described and is very close to P. caecus Micoletzky, 1924. The subspecies P. caecus opthalmophorus (Steiner, 1921), different from the typical caecus by the presence of ocelli, is considered as a different species; we therefore propose P.ophthalmophorus (Steiner, 1921) stat.n. The genus Paracanthonchus is redefined.     

Wide variation in a tiny space: The microdistribution of meiobenthos in an artificial pond

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The genus Paradorylaimus Andrássy, 1969 (Dorylaimoidea: Nematoda)

Examination of the type specimens of Dorylaimus parafecundus De Coninck, 1935 showed that the cuticle lacks longitudinal ridges. The species is a typical Laimydorus and is herewith redesignated L. parafecundus (De Coninck, 1935) n.comb. As it is the type species of Paradorylaimus Andrássy, 1969, the latter generic name falls as a synonym of Laimydorus Siddiqi, 1969 which has priority of publication. The three other species included originally in Paradorylaimus are dealt with as follows: P. wilhelmschneideri (Andrássy, 1959) is considered incertae sedis; P. heterurus (Schuurmans Stekhoven & Teunissen, 1938) was shown by Mulk et al. (1978) to belong in the genus Roqueus Thorne, 1964; P. filiformis (Bastian, 1865) is herewith returned to Laimydorus. Dorylaimus tenuistriatus Schneider, 1935 is not identical with L. parafecundus: it is more slender; odontostyle, pharynx and spicules are shorter; supplement number is lower; shape of vulva and the arrangement of the pharyngeal gland nuclei are different. The species is transferred to Laimydorus, becoming L. tenuistriatus (Schneider, 1935) n.comb. Lectotypes are designated for L. parafecundus and L. tenuistriatus. Among the material of L. tenuistriatus are specimens of L. pseudostagnalis (Micoletzky, 1927) and L. sp.     

Mychophilus palmatus, a new species (Copepoda: Cyclopoida: Ascidicolidae) associated with the compound ascidian Botryllus leachi Savigny, with remarks on congeneric species and related genera

Presently two species of the genus Mychophilus Hesse, 1865 are known: Mychophilus roseus Hesse, 1865 and Mychophilus fallax Stock, 1967. A hitherto unknown species is described herein as Microphilus palmatus n. sp. The new species is characterized by its urosome much exceeding the cephalosome-metasome in length, the ornamentation of the labrum, the shape of the palp of the first maxilla, the ornamentation of the legs 1–4 and shape of the caudal rami. These and other features of the genus Mychophilus are compared with those from other related genera of the family Ascidicolidae Thorell, 1859.     

Two new species of the genus Rhynchonema (Nematoda,Xyalidae) from Amakusa,south Japan

During the ecological studies on marine nematodes in the intertidal zone and an adjacent seagrass Zostera marina Linne bed in Amakusa, south Japan, two new species of the genus Rhynchonema Cobb, 1920 were found. They are described as R. kikuchii and R. amakusanum. Up to now, Rhynchonema species were unknown from Japan.     

Study of the genus Plectus Bastian, 1865 (Nematoda: Plectidae) from Iran

Three species of Plectus Bastian, 1865 viz., P. aquatilis and P. pusillus from Kerman province and P. velox from Alborz province, Iran are described and illustrated. Partial sequences of 18S region of ribosomal DNA gene were amplified for P. aquatilis and P. pusillus. The Blast results of population of P. aquatilis from Iran showed 8–10 nucleotides differences with populations of the same species (AF036602; GQ892827; AY284700) reported from the UK, Belgium and The Netherlands, respectively. Whereas Iranian population of P. pusillus showed 14–16 nucleotides differences with P. cf. pusillus (AY284705; AY284704) reported from The Netherlands. Molecular analysis revealed close relationship of the Iranian plectids with P. cf. parvus (AY284699) reported from The Netherlands. Phylogenetic relationships with other related species in the genus Plectus and closely related genera that are available in the GenBank are given.     

Alchemilla austriaca,spec. nova,(Rosaceae) — eine neue Art aus den Ostalpen

Alchemilla austriaca is a new species which belongs to the group ofA. demissa, A. frigens, A. longana, A. longiuscula, A. semisecta, andA. sinuata. The holotype specimen as well as leaf and flower details are illustrated (Figs. 1–3). A complete character analysis is given, differences and similarities of allied species are presented in two tables, and the position of the group within the genus is discussed.A. austriaca so far is known only from the Austrian Alps and mainly from the central ranges (distribution map: Fig. 4). Its wet subalpine and alpine habitats are characterized by species lists.

     

Redescription of Monhystrella parvella (Filipjev) comb.n. (Nematoda, Monhysteridae)

The type of material of Monhystrella parvella (Filipjev, 1931) comb.n. from Abyssinia (Ethiopia) is redescribed and figured in detail. Data on the genital system and the ontogeny of this species are given. Monhystera filiformis sensu Gerlach, 1951 nec Bastian, 1865 of the Black Sea at Pomorie (Bulgaria) is synonymised with M. parvella . The Black Sea specimens have a shorter pharynx, a longer tail and differ also from the Abyssinian specimens in the shape of the tail and the spinneret outlet.     

Elements pour une théorie statistique du tableau phytosociologique homogène

Summary A new model, based on information theory, for determining the equation of Raunkiaer frequency curves in a homogeneous phytosociological table is proposed. The forms of these curves are explained in relation to the geographical area covered by the relevés of the phytosociological table involved. The statistical distribution of species in a syntaxon (and the variability of a syntaxon as measured, by (E/E _m)-1, where E is the total number of species in the table, and E _m is the average number of species per relevé) are closely correlated with the size of the distribution area of relevés. Many examples are given and several consequences for the phytosociological method are indicated.

     

Three species of Tobrilidae (Nematoda: Enoplida) from Li River at Guiling, China

Eutobrilus annetteae Joubert & Heyns, 1979 with its male reported for the first time, Semitobrilus pellucidus (Bastian, 1865) Tsalolichin, 1983, and Epitobrilus allophysis(Steiner, 1919) Tsalolichin, 1996 are described from the Li River at Guiling, China. The male of Eutobrilus annetteae is characterized by lots of crystalloids inside body, almost straight spicules about one anal body diameter long and seven equally sized supplements. Semitobrilus pellucidus from Guiling shows large variation in body width, position of amphids, form of buccal cavity, distance between denticles, direction of vagina, arrangement of oocytes, and shape of eggs. It is different from other populations in its shorter cephalic setae, less than 60% of head width, in its shorter tail and smaller c value. In males, there are 6–9 supplements, reduced and irregulary spaced. Epitobrilus allophysisis characterized by its labial setae longer than 50% of head width, small, posteriorly located ovoid amphid, single egg occupying whole space of uterus and blunt tail tip.     

Vertical distribution of benthic nematodes in an oligotrophic lake: seasonality, species and age segregation

The vertical distribution of nematodes up to 20 cm sediment depth was studied over a one-year period in the alpine, oligotrophic lake Königssee. Ten water depths were examined, four of which correspond to the littoral (1 m, 2 m, 5 m, 10 m), three to the littoriprofundal (15 m, 20 m, 30 m) and three to the profundal (60 m, 120 m, 190 m). The sediment was devided into four layers (0–2 cm, 2–5 cm, 5–10 cm and 10–20 cm). (1) The highest proportion of nematodes was found in the top layer. Out of 45 263 nematodes, 89% were found in the first 5 cm of the sediment and only 1 % deeper than 10 cm. (2) The proportion of nematodes in the top layer increased along with water depth. Water depth was a better predictor of percentage of nematodes in the top layer than particle size or content of organic carbon in the sediment. (3) There were considerable differences among species in their vertical distribution in the sediment. (4) There was a significant trend for juveniles to occupy more superficial layers than adults across various species. (5) There are time related vertical preferences among adults and juveniles of several nematode species across the year, suggesting vertical migration in the sediment (e.g. Aphanolaimus aquaticus Daday, Eumonhystera longicaudatula Gerlach & Riemann, Tobrilus gracilis Bastian, Monhystera paludicola de Man, Ethmolaimus pratensis de Man and Ironus tenuicaudatus de Man). The factors determining the vertical variation in nematode abundance in freshwater systems across space and time are still unknown.     

Description of two species of free-living nematodes (Nematoda) from fresh waterbodies of Vietnam

The new nematode species Monhystera longivaginata sp. n. and the rare species Mononchulus nodicaudatus (Daday, 1901) collected in waterbodies of Vietnam are described. M. longivaginata sp. n. is morphologically similar to M. paludicola de Man, 1881, but differs from it in a longer and slenderer tail in females, ocelli situated closer to the anterior end of the body, the presence of a postvulval gland cell, and a longer vagina. The genus Monhystera Bastian, 1865 is revised, and several species of this genus (M. lemani Juget, 1969, M. macramphus Filipjev, 1923, M. amabilis Gagarin, 1997, M. hamata Gagarin et Nguyen Vu Thanh, 2005, and M. melnikae Gagarin et Naumova, 2010) are transferred to the genus Eumonhystera Andrássy, 1981 as E. lemani (Juget, 1969) comb. nov., E. macramphus (Filipjev, 1929) comb. nov., E. amabilis (Gagarin, 1997) comb. nov., E. hamata (Gagarin et Nguyen Vu Thanh, 2005) comb. nov., and E. melnikae (Gagarin et Naumova, 2010) comb. nov.     

A revision of the genus Sige Malmgren (Polychaeta: Phyllodocidae)

The genus Sige Malmgren, 1865 is revised and the type species S.fusigera Malmgren, 1865, redescribed from syntypes and newly collected topotype material. Based on examination of type specimens, six species described from other genera are transferred to Sige: Pirakia brunnea Fauchald, 1972; Vitiazia dogieli Ushakov, 1953; Eulalia longocirrata Stop-Bowitz, 1948; Eumida (Eumidaj parvicirrus Perkins, 1984; Eulalia sandwichensis Ushakov, 1975; Eulalia sigeformis Annekova, 1937. The genus Vitiazia Ushakov, 1953, being monotypic, becomes a junior synonym to Sige. Pirakia lanceolata Hartman & Fauchald, 1971 is synonymized with Sige longocirrata (Støp-Bowitz, 1948) and Sige oliveri sp. nov. is described from western Norway and Sweden. Ten species are recognized as belonging to Sige. The relationships of Sige to other genera are discussed.     

Verbreitung und Ökologie derVaucheria-Arten (Tribophyceae) des Elbe-Ästuars und der angrenzenden Küste

From the Elbe estuary and the adjacent North Sea coast, 19 species ofVaucheria are on record. Their horizontal and vertical distribution pattern as well as their association with macrophyte communities are described. With regard to ecological salinity tolerance and distribution below or above mean high water, 7 ecological groups ofVaucheria species are defined. Dominating species which form extensive algal mats in the upper eulittoral zone areVaucheria compacta var.dulcis (freshwater and oligohalinic section of the estuary),V. compacta var.compacta (mesohalinic section) andV. velutina together withV. subsimplex (polyhalinic and euhalinic section). The rare speciesV. vipera is recorded for the first time from the German coast.

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Herrn Dr. Dr. h. c. Peter Kornmann zum 80. Geburtstag gewidmet.

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Adressat für Sonderdruckwünsche: Prof. Dr. L. Kies.