• B. Tallosi, A.Peters and R.-U. Ehlers. Steinernema bicornutum sp. n. (Rhabditida: Steinernematidae) from Vojvodina, Yugoslavia, 71-80.
• V.G. Gagarin. Free-living nematodes recovered from sewage disposal sites at the Rybinsk water reservoir, Borok, Russia, 81-84.
• S.E. Spiridonov and T.T. Bai. A Gnathostoma juvenile (Spirurida: Gnathostomatoidea) recovered from the coelomic cavity of an earthworm from Laos, 85-88.
• V.N. Chizhov, S.A. Subbotin and N.N. Zakharenkova. Thripinema khrustalevi sp. n. (Tylenchida: Allantonematidae), a parasite of Thrips (Thysanoptera) in Moscow, 89-94.
• E. van den Berg and P. Queneherve. Hemicycliophora paracouensis sp. n. and a note on Criconemoides ornativulvatus Van den Berg & Queneherve, 1993 from French Guiana (Tylenchida: Criconematinae), 95-104.
• E. Vouyoukalou and S. Gowen. Evaluation of Pasteuria penetrans as a biocontrol agent against populations of root-knot nematodes from Crete, 105-110.
• A. Yu. Ryss and S. Bostrom. Geocenamus semicircularis (Tylenchida: Belonolaimidae) from East Falkland Island in the Subantartic and its taxonomic status, 111-116.
• A. V. Tchesunov. Taxonomy, morphology and ultrastructure of the free-living marine nematode Pselionema simplex De Coninck, 1942 (Chromadoria: Ceramonematidae), 117-130.
• Book Reviews, 131-135.

Tallosi, B., Peters, A. and Ehlers, R.-U.

Steinernema bicornutum sp. n. (Rhabditida: Steinernematidae) from Vojvodina, Yugoslavia

Summary:
Steinernema bicornutum sp. n., isolated from soil samples taken in Strazilovo, Vojvodina, Yugoslavia by baiting with last instar Galleria mellonella, is distinguished from other members of the genus Steinernema by two protruding horn-like papillae on the head of the dauer juvenile. The average length of the dauer stage is 770 µm, the lateral field has 8 ridges. Only second generation females and males bear a small tail mucron. Two different spicule types occur in first generation males. The species did not hybridize with S. carpocapsae and S feltiae, the latter also isolated from the type locality. Its restriction fragment length pattern of the internal transcribed spacer region of the ribosomal DNA repeat unit differ from other Steinernema species. Dauer juveniles with similar horn-like structures have been recorded from Spain and Germany. Axenic and monoxenic cultures of new species were established on artificial media. An improved time-saving method to dehydrate nematodes for permanent preparations is described.

Key words: entomopathogenic nematode, Steinernema bicornutum sp. n., Vojvodina, Yugoslavia, description.

Gagarin, V.G.

Free-living nematodes recovered from sewage disposal sites at the Rybinsk water reservoir, Borok, Russia

Summary:
In sewage disposal sites at the Borok settlement 47 nematode species were recovered including 13 secernentean species. Several trends in species and nematofauna distribution along the pollution gradient were determined.

Key words: free-living nematodes, fresh water ecology, antropogenous pollution.

Spiridonov, S.E. and Bai, T.T.

A Gnathostoma juvenile (Spirurida: Gnathostomatoidea) recovered from the coelomic cavity of an earthworm from Laos

Summary:
A gnathostomatid juvenile was found in the coelomic cavity of an earthworm, Pheretima lunata collected near a pig farm in Thakhek, South Laos. In the general shape of the body and the disposition of the hooks on the head-bulb the juvenile nematode resembled Gnathostoma doloresi Tubangui, 1923.

Key words: Gnathostoma, juvenile stage, morphology, surface structure, SEM, earthworm host.

Chizhov, V.N. , Subbotin, S.A. and Zakharenkova, N.N.

Thripinema khrustalevi sp. n. (Tylenchida: Allantonematidae), a parasite of Thrips (Thysanoptera) in Moscow

Summary:
Specimens of Thripinema khrustalevi sp. n. were recovered from Thrips (Thrips trehernei Prisner. and T. physopus L.) associated with the flowers of Taraxacum officinale Wigg. and Hieracium spp. (Compositae) in Moscow lawns. Thripinema khrustalevi sp. n. can be distinguished from the related species T. aptini (Sharga, 1932) Siddiqi, 1986 and T. reniraoi (Reddy, Nickle & Rao, 1982) Siddiqi, 1986 by differences in the structure of the bursa, the shape of the male tail, and, the presence of basal knobs on the stylet in infective females. The new species can be distinguished from T. nicklewoodi Siddiqi, 1986 by the position of the orifice of the dorsal esophageal gland in infective females and the absence of a tail cone in the parasitic female. Transmission electron microscopy analysis showed that parasitic females did not have cuticle and their integument consisted of microvilli. The microvilli were coated by the thin covering layer. An identification key for the genus Thripinema is given.

Key words: Thripinema khrustalevi sp. n., thrips, integument, ultrastructure, Russia, identification key.

Van den Berg, E. and Queneherve, P.

Hemicycliophora paracouensis sp. n. and a note on Criconemoides ornativulvatus van den Berg & Queneherve, 1993 from French Guiana (Tylenchida:Criconematinae)

Summary:
Hemicycliophora paracouensis sp. n. is described and illustrated from specimens collected from the rhizosphere of Dicorynia guianensis Amshoff, a forest tree growing near Paracou, west of Cayenne, French Guiana. Females are characterized by 283-339 smooth annuli, lateral field consisting of breaks in striae, rare anastomoses, anus situated far posterior of the vulva (104-152 µm, RVan = 36-49 and VA%T = 97-128 %), long vulval lips and a vulval sheath with ten to fourteen annuli, a long, gradually tapering tail and a 103-115 µm long stylet. Females and juveniles of Criconemoides ornativulvatus Van den Berg & Queneherve', 1993 were present in the same sample and the juveniles are described here, together with comments on the females.

Key words: Criconemoides, French Guiana, Hemicycliophora paracouensis sp. n., nematodes, taxonomy.

Vouyoukalou, E. and Gowen, S.

Evaluation of Pasteuria penetrans as a biocontrol agent against populations of root-knot nematodes from Crete

Summary:
The attachment of spores from different populations of Pasteuria penetrans was assessed using a field population of root-knot nematodes from Crete consisting of 75% Meloidogyne incognita and 25% M. javanica. Juveniles were more heavily encumbered with spores of an isolate of P. penetrans from South Africa and from a population consisting of a mixture of P. penetrans isolates than by spores from two other populations. When single egg mass lines of the component species of the Cretan root-knot nematode population were tested, it was found that M. javanica was the more susceptible species. A greater proportion of the nematodes encumbered with 5-8 spores eventually became infected than did juveniles that were encumbered by fewer spores.

Key words: Meloidogyne incognita, M. javanica, biological contiol, Pasteuria penetrans, variability.

Ryss, A.Yu. and Bostrom, S.

Geocenamus semicircularis (Tylenchida:Belonolaimidae) from East Falkiand Island in the Subantarctic and its taxonomic status

Summary:
Nematode specimens collected from East Falkland Island were identified as Geocenamus semicircularis (Luth & Decker, 1985). These specimens were indistinguishable from G. nothus (Mien, 1955), therefore G. semicircularis (Luth & Decker, 1985) is here proposed as junior synonym of G. nothus (Allen, 1955). Data on morphometrics and drawings and SEM photographs of these nematodes are given.

Key words: Geocenamus nothus, G. semicircularis, taxonomy, East Falkland Island, SEM, synonymy.

Tchesunov, A.V.

Taxonomy, morphology and ultrastructure of the free-living marine nematode Pselionema simplex De Coninck, 1942 (Chromadoria: Ceramonematidae)

Summary:
The free-living marine nematode Pselionema simplex De Coninck, 1942 (Ceramonematidae) is redescribed together with an examination of some ultrastructural details. The species is recorded in the White Sea for the first time. The body cuticle consists of broad rigid annules connected with thinner flexible interconnections. The annules are ultrastructurally simple and formed with a thick electron-lucent layer with thin electron-dense coverings on the external and internal sides. Interconnections are multilayered. The annule electron-lucent material corresponds to the exocuticle, and interconnections - to the endocuticle. The cuticle of the cephalic end is very slightly modified. The pharynx consists of the procorpus, elongated narrowed isthmus and posterior widening. Radial myofilaments are revealed in the procorpus and isthmus only, whereas the posterior widening is built with pharyngeal gland cell bodies. The mid-gut is composed of four epithelial cells as viewed in transversal sections. The recto-intestinal valve cells possess rather long microvilli directed into the rectal lumen; a cuticular covering is not present.

Key words: Pselionema simplex, Ceramonematidae, redescription, ultrastructure, cuticle, pharynx, cephalic end, rectum.