Synopsis of gastropod-associated nematodes of Ciscaucasia (Russian Federation) with the description of a new species of Pellioditis Dougherty, 1953 (syn. Phasmarhabditis Andrássy, 1976).

Caucasus is known as one of the few biodiversity hotspots in Europe and is characterised by rich gastropod fauna while the nematode fauna in association with gastropods has remained largely understudied. Surveys conducted in 2019 and 2021 in the North Caucasus of the Russian Federation (Stavropol Upland and western and central parts of Krasnodar Krai) has revealed the presence of three new species of Pellioditis, a facultative parasite of land gastropods, and two species of obligate parasites, the intestinal parasite Angiostoma kimmeriense and a new, still undescribed species of a larval ectoparasite Alloionema sp. The new associations of Cruznema sp. and Rhabditophanes sp. with land gastropods were recorded for the first time in the Russian Federation. The new species of Pellioditis Dougherty, 1953 described here is based on the analysis of morphology and molecular studies of two distant and morphologically distinct strains, thermalis and sindicae. Pellioditis thermalis n. sp. was characterised by females possessing a tail of about 95-100 µm long, broadly conical in shape in the thermalis and sindicae strains, with a rounded anterior part and a subulate terminal part as long as the former; prominent phasmids located at the mid-tail, equatorial vulva position, a lateral field of three ridges (four incisions), males with spicules featuring a hole at the distal tip, ensheathed infective juveniles with average length 717 µm in the thermals strain and 771 µm in the sindicae strain, and exsheathed ones 644 µm and 682 µm, respectively. ITS-based phylogenetic analyses revealed that all Pellioditis species found in Ciscaucasia and Transcaucasia probably belong to two separate clades, with independent evolutionary histories of colonisation of this area. The entire Caucasus range area appears to serve as a biodiversity hotspot for the genus Pellioditis, presumably due to its complicated geological history and repeated isolation events for its terrestrial mollusc hosts.

Photorhabdus lux-operon heat shock-like regulation.

For decades, transcription of Photorhabdus luminescens lux-operon was considered being constitutive. Therefore, this lux-operon has been used for measurements in non-specific bacterial luminescent biosensors. Here, the expression of Photorhabdus lux-operon under high temperature was studied. The expression was researched in the natural strain Photorhabdus temperata and in the heterologous system of Escherichia coli. P. temperata FV2201 bacterium was isolated from soil in the Moscow region (growth optimum 28 °C). We showed that its luminescence significantly increases when the temperature rises to 34 °C. The increase in luminescence is associated with an increase in the transcription of luxCDABE genes, which was confirmed by RT-PCR. The promoter of the lux-operon of the related bacterium P. luminescens ZM1 from the forests of Moldova, being cloned in the heterologous system of E. coli, is activated when the temperature rises from room temperature to 42 °C. When heat shock is caused by ethanol addition, transcription of lux-operon increases only in the natural strain of P. temperata, but not in the heterologous system of E. coli cells. In addition, the activation of the lux-operon of P. luminescens persists in E. coli strains deficient in both the rpoH and rpoE genes. These results indicate the presence of sigma 32 and sigma 24 independent heat-shock-like mechanism of regulation of the lux-operon of P. luminescens in the heterologous E. coli system.

Larval spirurids in a supralittoral amphipod in the north-east of Russia and the identification of the intermediate host of Antechiniella septentrionalis (Spirurida: Acuariidae), parasitic in a tundra vole.

The supralittoral amphipod Traskorchestia ditmari (Derzhavin, 1923) was identified as the intermediate host for Antechiniella septentrionalis Ivanova, Dokuchaev & Spiridonov, 2019, a parasite of the tundra vole Microtus oeconomus and Skrjabinocerca sp. (both Spirurida: Acuariidae) in Magadan Oblast in north-eastern Russia. Joint infection by both larval spirurids was not observed. The infective stage of A. septentrionalis was the encysted larvae, while larvae of Skrjabinocerca sp. were free in the amphipod's coelom. The identity of A. septentrionalis was confirmed using cox1 mtDNA gene analysis, performed on adult stages from a tundra vole and on larvae from amphipods. Possible transmission routes of A. septentrionalis are discussed.

Antechiniella septentrionalis n. sp. (Spirurida: Acuariidae), a new intestinal nematode parasite of the tundra vole Microtus oeconomus (Pallas) (Rodentia: Muridae) in the north-east of Russia.

Antechiniella septentrionalis n. sp. (Spirurida: Acuariidae) is described from the duodenum of a tundra vole, Microtus oeconomus (Pallas), collected in the Magadan region in the north-east part of Russia. It differs from A. suffodiax (Beveridge & Barker, 1975) and A. sertatum Smales, 1991 mainly in having a larger number of postcloacal papillae (5-6 pairs vs 4 pairs), a differently shaped left spicule, the disposition of precloacal papillae in two rows vs one, and oblong vs oval eggs. Other differences include the different disposition of ovaries in A. septentrionalis n. sp and A. suffodiax and the different structure of deirids in A. septentrionalis n. sp. and A. sertatum. The new species was characterized molecularly (partial sequences for 18S rRNA, 28S rRNA and cox1 mtDNA). The phylogenetic analyses performed showed the affinity of the new species to the members of the Acuariidae and other spirurid nematodes.

[RIBOSOMAL DNA INTERNAL TRANSCRIBED SPACER 2 SEQUENCE AS A PHYLOGENETIC MARKER FOR THE IDENTIFICATION OF TRICHINELLA NEMATODES].

The results of testing several primer combinations were used to choose an optimal pair for the amplification of the internal transcribed spacer 2 (ITS2) region of ribosomal DNA (direct: Tri58s F 5 CGG TGG ATC RCT TGG CTC GTA CG and reverse: AB28 Rr (CGA CCG CTT ATT GAT ATG C). This pair of primers yields a 900 bp PCR product. Comparative analysis of obtained ITS2 sequences, for 8 Trichinella isolates from different regions of the Russian Federation permits different species and individual genotypes of these parasitic nematodes to be validly distinguished.

[Cuticle ultrastructure of the fresh-water horsehair worm Gordionus alpestris (Villot, 1885) (Nematomorpha)].

The cuticular structure of the horsehair worm Gordionus alpestris (Villot, 1885) was studied under scanning and transmission electron microscopes. Adult worms were collected in the Syuk River near Nickel' Village in the Republic of Adygea (Russia) in June 2013. In the sampling area, the G. alpestris juveniles parasitize diplopods Pachyiulus krivolutskyi Golovatch, 1977. Similarities with other Nematomorpha species with the known cuticle ultrastucture are discussed.

[ANIMAL TOXOCARIASIS IN A MEGALOPOLIS: EPIDEMIC ASPECTS].

The prevalence of toxocariasis was studied among a population of domestic and stray dogs and cats. In a megalopolis, Toxocara invasion was 31.6% in a population of cats and 82 and 25.4% in that of puppies and dogs, respectively. A method was developed for the molecular genetic identification of T. cati and T. canis.

[Diversity of the rDNA ITS haplotypes of the nematodes Haemonchus contortus (Trichostrongyloidea, Rhabditida) of the same host].

Specimens sampled in Central Mongolia have been examined for the intraspecific polymorphism of the nucleotide sequences of ribosomal DNA internal transcribed spacers (ITS-1 + 5.8S + ITS-2) of the parasitic nematode Haemonchus contortus. A considerable diversity of haplotypes differing in the nucleotide composition of this DNA region has been observed. The phylogenetic relationships between the haplotypes detected in Central Mongolia and the corresponding sequences from other parts of the nematode distribution area (deposited with the NCBI GenBank) have been analyzed. Significantly different sequences have been found along with the haplotypes already observed in H. contortus or differing from them by one-two nucleotides.

[Molecular taxonomic identification of Trichinella spp. from the Arctic coasts of the Russian Federation].

Epizootological surveys on the Arctic coasts of the Russian Federation revealed 8 terrestrial andmarine mammal species that were Trichinella carriers. The infection rate varied with the animal species from 1.6 to 92.8%. Analysis of the taxonomic affiliation of Trichinella isolated from the muscles of the terrestrial and marine mammals indicated that the Trichinella species T. nativa was widespread in the arctic areas of the Russian Federation. Analysis of sequences in the Cob gene of mtDNA revealed nucleotide differences between several isolates of this species.

Two new species of creagrocercid nematodes parasitic in earthworms, with comments on the phylogenetic affiliations of the Creagrocercidae Baylis, 1943.

Two new species of the rare nematode family Creagrocercidae from earthworms are described and illustrated. Creagrocercus braziliensis n. sp. is distinguished from the type-species, C. barbatus Baylis, 1943, by: the presence of four cephalic papillae (vs a pair of finger-shaped latero-ventral processes) on the head; larger amphids; a more posterior excretory pore position; a shorter pharynx which is remarkably expanded at the base; the nerve-ring situated just posterior to the base of the pharynx (vs at mid-pharyngeal level); an anal aperture present in the females; anterior ovary and testis reach just into the anterior half of the body (vs closely posterior to the pharynx); equal, similar (vs unequal, dissimilar) spicules; and a prominent, unpaired precloacal papilla in males. Creagrocercus drawidae n. sp. is related to C. barbatus by a similar pharyngeal shape and the presence of a tail 'hook', and to C. braziliensis n. sp. by: the lack of finger-shaped processes on the head and the presence of four cephalic papillae; a similar position of the excretory pore; a similar arrangement and length of the reproductive system; the presence of unpaired precloacal papilla in males; similar, almost equal spicules; and the presence of a tail 'hook'. From both of these species C. drawidae differs by having: a much shorter body and pharynx; larger amphids; a more posterior nerve-ring position; larger and less numerous eggs; greatly inflated (vs flat) vulval lips; shorter spicules; and a smaller caudal 'hook'. For C. drawidae, the partial sequences of the SSU (18S) rDNA and the D2D3 segment of LSU (28S) rDNA were obtained and subjected to phylogenetic analyses. The phylogenetic affiliations of the Creagrocercidae are discussed.

Angiostoma glandicola sp. n. (Nematoda: Angiostomatidae): a parasite in the land snail Megaustenia sp. from the Cat Tien Forest, Vietnam.

The nematode Angiostoma glandicola sp. n. found parasitizing Megaustenia sp. snails (Pulmonata: Helicarionidae) collected in Dong Nai Province, Vietnam, is described and illustrated. The new species is characterized by its unusual host location (the digestive gland) and in having: two circles of cephalic probolae, six lips each bearing two prominent papillae, amphids situated at posterior of lips, the presence of lateral alae, an enlarged stoma, a club-shaped pharynx with cuticularized valves in the bulb, the nerve ring situated on the junction of the corpus and isthmus and the excretory pore opposite the bulb. Oviparous females have a mid-body vulva position, long reflexed ovaries and short divergent uteri, and a conical tail with a slightly triangular tip. Males have long, curved, not distinctly cephalate spicules and a small gubernaculum, nine pairs of pedunculate genital papillae (GP) incorporated into the bursa (three precloacal, six postcloacal in two groups: GP 4-7 closely behind the cloaca and GP 8-9 distanced), of which GP 5 and 8 terminate on dorsal edge of the bursa and GP 8 and 9 are fused at the base, the bursa nearly reaches the tail tip, unpaired precloacal GP and a pair of ventral circumcloacal GP not incorporated into bursa. It clearly differs from other species of the genus by having cephalic probolae vs. no cephalic probolae and the specific number and disposition of male GP. A partial sequence of D2D3 large subunit (LSU) rDNA was obtained and subjected to phylogenetic analyses. Relationships within the Angiostoma genus are discussed.

[A new hairworm in the genus Chordodes (Nematomorpha: Chordodidae) from the Minusinsk depression]. / Novyi volosatik roda Chordodes (Nematomorpha: Chordodidae) iz Minusinskoi kotloviny.

The gordian worm collected in July 1885 in the Gussevski pond on the Lugovka River, 30 km from Minusinsk, Siberia and identified as "Parachordodes kashgaricus Camerano, 1897" is described as a new species, Chordodes sajanensis sp. n.

Dacochordodes bacescui Capuse, 1966: Report of the first two isolations from humans.

This report describes two cases of isolation of Dacochordodes bacescui Capuse, 1966 from human intestinal infections. In the first case, two adult worms were identified in the vomitus of a man suffering from abdominal pain and nausea. In the second case, a worm was passed in the stool of a woman suffering from abdominal pain and pruritus. Human gastrointestinal infection with this parasite has not previously been reported.

[Embryonic development of Trichocephalus trichiurus and Eucoleus oesophagicola (Nematoda, Trichocephalida)]. / Embrional'noe razvitie Trichocephalus trichiuris i Eucoleus oesophagicola (Nematoda, Trichocephalida).

The embryonal development of Trichocephalus trichiurus and Eucoleus oesophagicola is described. Clevage of both species is full, bilaterally-symmetrical, determined. At the two blastomere stage the epidermis material is localized in the anterior one. The development of both species lacks the rhomb figure characteristic of nematodes. The mouth opening breaks independent of blastopore. The stylet anlage formation was noted for T. trichiurus.