New data on Longidorus aetnaeus Roca, Lamberti, Agostinelli & Vinciguerra, 1986 (Nematoda: Longidoridae) from Iran and Ajaria (Georgia).

Longidorus aetnaeus Roca, Lamberti, Agostinelli & Vinciguerra, 1986 is reported for the first time from Iran and Ajaria (Georgia). Morphological and morphometric data are provided for two Iranian and one Ajarian populations. The D2-D3 region of 28S rDNA for both Iranian populations was sequenced for the first time and the data reported. A detailed study of juveniles of L. aetnaeus from Iran, Georgia and Bulgaria demonstrated that this species develops through three juvenile stages. Furthermore, phylogenetic studies inferred from sequences for the D2-D3 region of 28S rRNA gene revealed that L. aetnaeus is most closely related to L. leptocephalus.

Terrestrial nematodes from the Maritime Antarctic.

Background: Soil nematodes are one of the most important terrestrial faunal groups in Antarctica, as they are a major component of soil micro-food webs. Despite their crucial role in soil processes, knowledge of their species diversity and distribution is still incomplete. Taxonomic studies of Antarctic nematodes are fragmented, which prevents assessment of the degree of endemicity and distribution of the species, as well as other aspects of biogeography. New information: The present study is focused on the nematode fauna of one of the three Antarctic sub-regions, the Maritime Antarctic and summarises all findings published up to April 2023. A species list that includes 44 species, belonging to 21 genera, 16 families and eight orders is provided. A review of the literature on terrestrial nematodes inhabiting the Maritime Antarctic showed that the sites are unevenly studied. Three islands (Signy, King George and Livingston Islands) revealed highest species richness, probably due to the highest rates of research effort. Most species and four genera (Antarctenchus, Pararhyssocolpus, Amblydorylaimus and Enchodeloides) are endemic, proving that nematode fauna of the Maritime Antarctic is autochthonous and unique. Several groups of islands/sites have been revealed, based on their nematode fauna. The study showed that species with a limited distribution prevailed, while only two species (Plectusantarcticus and Coomansusgerlachei) have been found in more than 50% of the sites. Based on the literature data, details on species localities, microhabitat distribution, plant associations and availability of DNA sequences are provided.

Molecular and morphological characterisation of Longidoruspolyae sp. n. and L.pisi Edward, Misra & Singh, 1964 (Dorylaimida, Longidoridae) from Bulgaria.

Longidoruspolyae sp. n., a bisexual nematode species found in the rhizosphere of pear tree (Pyruscommunis L.), is described and characterised using an integrative approach. The new species has a female body length of 6.8-9.1 mm; a comparatively long odontostyle (114.0-127.5 µm); a narrow lip region (14.0-15.5 µm), anteriorly flattened and almost continuous with the body profile; pocket-like amphidial pouches long, deeply bilobed, and slightly asymmetrical, a guide ring at 37-42 µm from the anterior end; normal arrangement of pharyngeal glands; and a short bluntly rounded to hemispherical tail. Four juvenile stages identified: the first stage with a digitate tail, and the second and subsequent stages with a bluntly rounded tail. Males have one adcloacal pair and a row of 10 or 11 single ventromedian supplements; spicules 71.0-74.5 µm long. Based on morphometric data, the new species belongs to a group of species spread over Europe (L.arthensis, L.silvae, L.uroshis,), Iran (L.kheirii), and Syria (L.pauli), which share common characters such as amphidial fovea, lip region and tail shapes, similar odontostyle and body length, and similar first-stage juvenile tail shape. Codes for identifying the new species are A5, B2, C34, D3, E3, F45, G12, H1, I2, J1, K7. The phylogenetic analysis based on D2-D3 expansion domains of the rRNA gene revealed that the new species has the closest relationships with L.athesinus from Italy and three unidentified Longidorus spp. from USA (Longidorus sp. 1, Longidorus sp. 2, and Longidorus sp. 6). New morphometric and molecular data (18S rRNA gene, ITS1-5.8S-ITS2 regions and D2-D3 28S rRNA gene sequences) for three populations of L.pisi from Bulgaria were obtained and variations between populations are discussed.

Ditylenchus sarvarae sp. n. (Tylenchina: Anguinidae) from Iran.

During a survey of soil nematodes in Iran, a new species of Ditylenchus Filipjev, 1936 was discovered. Ditylenchus sarvarae sp. n. is characterised by its body length (1.0-1.4 mm), lateral field with seven incisures and without areolation, long postuterine sac (1.8-2.8 times the corresponding body diameter) and conical female tail with pointed tip (68-89 µm long, c = 13.7-18.2, c' = 4.2-5.1). Male specimens have conical tails (64-70 µm long, c = 14.5-16.7, c' = 4.0-4.5), spicules (22-26 µm long) and gubernaculum (8-10 µm long). Measurements and illustrations are provided for this new species. A molecular study of the 28S rDNA region of D. sarvarae sp. n. demonstrates that the Iranian species belongs to a separate group compared with the other molecularly characterized species of genus Ditylenchus.

Biogeography and phylogenetic position of Enchodeloides signyensis (Loof, 1975), gen. n., comb. n. from Maritime Antarctic (Nematoda, Nordiidae).

The taxonomic position of the endemic Antarctic species Enchodeloides signyensis (Loof, 1975), gen. n., comb. n. (= Enchodelus signyensis Loof, 1975) is discussed on the basis of morphological study, including SEM, morphometric data, postembryonic observations, and sequence data of 18S rDNA and the D2-D3 expansion fragments of the large subunit rDNA. A number of characters such as the cuticle and stoma structures, including the presence of moderately developed cuticularised ring around the oral aperture, peculiarities of pharynx expansion, size and position of the posterior pair of pharyngeal nuclei, a less complex uterus, and the position of a posterior ventromedian supplement show that this species differs substantially from the other members of the genus Enchodelus. Furthermore, both the 18S and 28S rDNA-based phylogenetic trees of the Enchodelus sequences available in the GenBank formed two distinct clusters with E. signyensis being a part of a well-supported group with species of the genus Pungentus; therefore, it is proposed that its taxonomic position should be reconsidered.

New data on two remarkable Antarctic species Amblydorylaimusisokaryon (Loof, 1975) Andrássy, 1998 and Pararhyssocolpusparadoxus (Loof, 1975), gen. n., comb. n. (Nematoda, Dorylaimida).

The taxonomic position of two antarctic dorylaimid species Amblydorylaimusisokaryon (Loof, 1975) Andrássy, 1998 and Pararhyssocolpusparadoxus (Loof, 1975), gen. n., comb. n. are discussed on the basis of morphological, including SEM study, morphometric, postembryonic and sequence data of 18S rDNA and the D2-D3 expansion fragments of large subunit rDNA. The evolutionary trees inferred from 18S sequences show insufficient resolution to determine the assignment of the two species to particular families, moreover Pararhyssocolpusparadoxus gen. n., comb. n. (=Rhyssocolpusparadoxus) previously regarded as a member of Nordiidae or Qudsianematidae, showed distant relationship both to Rhyssocolpusvinciguerrae and Eudorylaimus spp. The phylogram inferred from 28S sequences revealed that Amblydorylaimusisokaryon is a member of a well-supported group comprised of several Aporcelaimellus spp., while, no close relationships could be revealed for the Pararhyssocolpusparadoxus gen. n., comb. n. to any nematode genus. On the basis of molecular data and morphological characteristics, some taxonomic changes are proposed. Amblydorylaimusisokaryon is transferred from family Qudsianematidae to family Aporcelaimidae, and a new monotypic genus Pararhyssocolpus gen. n. is proposed, attributed to Pararhyssocolpidaefam. n. The diagnosis of the new family is provided together with emended diagnosis of the genera Amblydorylaimus and Pararhyssocolpus gen. n. Data concerning distribution of these endemic genera in the Antarctic region are also given.

Calcaridorylaimus castaneae sp. n. (Nematoda, Dorylaimidae) from Bulgaria with an identification key to the species of the genus.

An unknown species belonging to the genusCalcaridorylaimus Andrássy, 1986 was collected from the litter of broadleaf forests dominated by Castanea sativa Mill. and mixed with Quercus daleshampii Ten. and Fagus sylvatica L. on Belasitsa Mountain, south-western Bulgaria. Calcaridorylaimus castaneae sp. n. is characterised by its long body (1.4-2.1 mm), lip region practically not offset, vulva transverse, short odontostyle (14.5-16 µm) and tail (75.5-110.5 µm, c=14.7-23.6; c'=2.9-4.4) in females and 38-46 µm long spicules with small spur before their distant end in males. It is most similar to C. andrassyi Ahmad & Shaheen, 2004, but differs in having transverse vs pore-like vulva and shorter spicules (38-46 µm vs 52-57 µm). An identification key to the species of the genus Calcaridorylaimus is proposed. Phylogenetic analyses were performed on 18S and D2-D3 expansion domains of 28S rRNA genes by Neighbor-Joining, Maximum Likelihood and Bayesian Inference methods. The phylograms inferred from 18S sequences showed closest relationships of the new species with some species belonging to the genus Mesodorylaimus. However, insufficient molecular data for members of both genera do not allow the phylogenetic relationships of Calcaridorylaimus and the new species described herein to be elucidated.

Studies of the genus Enchodelus Thorne, 1939 (Nematoda, Nordiidae) from Arctic polar deserts. 1. Species with long odontostyle: E. makarovae sp. n. and E. groenlandicus (Ditlevsen, 1927) Thorne, 1939, with an identification key to the species of the E. macrodorus group.

Two nematode species of the genus Enchodelus Thorne, 1939, one new and one known from Arctic polar deserts were studied. Enchodelus makarovaesp. n. is an amphimictic species, characterised by females with body length of 1.57-2.00 mm, lip region 15-17.5 µm wide, amphid duplex, odontostyle 38-43 µm long or 2.3-2.8 times lip region diam. Odontophore with flanges, 1.2-1.4 times as long as odontostyle; pharynx length 320-377 µm, pharyngeal expansion 113-130 µm long or 32-37% of total pharynx length; female genital system amphidelphic, uterus tripartite, pars refringens vaginae with two trapezoid sclerotisations, vulva a transverse slit (V=45-51%); tail bluntly conoid (25-35 µm, c=45.8-70.3, c'=0.6-0.9 in females, and 29-33 µm, c=46.4-58.9, c'=0.7-0.8 in males). Males with 65-74 µm long spicules and 10-12 spaced ventromedian supplements. Additional information for Enchodelus groenlandicus is provided, this being a new geographic record for the Putorana Plateau, Russian Arctic.

Longidorus carniolensis sp. n. (Nematoda, Longidoridae) from vineyard soil in Slovenia.

A new needle nematode, Longidorus carniolensissp. n., recovered from the soil around the roots of grapevine Vitis vinifera L. from Slovenia, is described and illustrated. Longidorus carniolensisis an amphimictic species, characterised by females with a moderately long (L=5.6-8.2 mm) and plump (a=51-72.4, ave. 66.3) body, assuming a spiral to C-shape when heat relaxed. Head region continuous, anteriorly almost flat, lip region 23-25 µm wide; guiding ring situated posteriorly (42-47 µm, 43-50 µm in males), odontostyle long (ave. 146.6 (136-157) µm); pharyngeal glands with normal location, their nuclei of approximately equal size; tail bluntly conoidal to almost hemispherical. Males abundant, spicules slender and long (122-145 µm), ventromedian supplements 13-17, irregularly spaced, preceded by an adanal pair. Four juvenile stages present, the first stage juvenile with bluntly conoidal tail. Codes for identifying the new species when using the key by Chen et al. (1997) are: A 56, B 4, C 4, D 1, E 4, F 35, G 1, H 1, I 2. The new species is morphologically the most similar to Longidorus poessneckensis Altherr, 1974, Longidorus macrosoma Hooper, 1961, Longidorus caespiticola Hooper, 1961, Longidorus helveticus Lamberti et al., 2001, Longidorus macroteromucronatus Altherr, 1974, Longidorus pius Barsi & Lamberti, 2001, Longidorus raskii Lamberti & Agostinelli, 1993, Longidorus kheirii Pedram et al. 2008, Longidorus silvae Roca, 1993, Longidorus iuglandis Roca et al., 1985, Longidorus vinearum Bravo & Roca, 1995 and Longidorus major Roca & d'Erico, 1987, but differs from these species either by the body and odontostyle length, position of guide ring, head region and tail shape or the shape of the first stage juvenile tail. Sequence data from the D2-D3 region of the 28S rDNA distinguishes this new species from other speciesof the genus Longidorus with known sequences. Relationships of Longidorus carniolensissp. n. with other Longidorus species based on analysis of this DNA fragment and morphology are discussed.