Stela Lazarova

Description of Longidorus cholevae sp. n. (Nematoda, Dorylaimida) from a riparian habitat in the Rila Mountains, Bulgaria

Abstract A description is provided of Longidorus cholevae sp. n., a bisexual species associated with wild cherry (Prunus avium L.) from the Rila Mountains, Bulgaria. The position of L. cholevae sp. n. among other species of the genus was elucidated by using morphological and molecular data. Phylogenetic analyses were performed of D2-D3 expansion domains of the 28S rRNA and the partial ITS1 containing regions by Neighbor-Joining, Maximum Likelihood and Bayesian Inference methods. The species is characterised by a female body length of 6.1–8.1 mm; long odontostyle (106–129 μm); lip region wide (21.5–24 μm) rounded and continuous with the body profile; amphidial pouches short and wide, funnel-shaped; a posteriorly situated guide ring (30–37 μm); normal arrangement of pharyngeal glands, and short bluntly rounded to hemispherical tail. Four juvenile stages indentified, first stage with elongate conoid tail. Males with 2–4 adanal pairs and a row of 11–13 single ventromedian supplements, spicules 96–120 μm long. Based both on morphological and molecular data the new species appearred to be the most similar witha group of species distributed in Europe sharing common charcters such as amphidial fovea, lip region and tail shapes, and having similar odontostyle and body length: L. poessneckensis, L. caespiticola, L. macrososma, L. helveticus, L. carniolensis and L. pius. An updated list of Longidorus species and a partial polytomous keys to the Longidorus species with long odontostyle (code A45) and short tail (code H1) are provided.

Morphological and molecular characterisation, and phylogenetic position of X. browni sp. n., X. penevi sp. n. and two known species of Xiphinema americanum-group (Nematoda, Longidoridae)

Abstract Using ribosomal (18S, ITS1, ITS2, D2-D3 expansion segments of 28S rDNA) and mitochondrial (partial cox1 and nad4) DNA markers in a study of several populations of Xiphinema americanum-group from Europe and Morocco, two cryptic species Xiphinema browni sp. n. (formerly reported as Xiphinema pachtaicum) and Xiphinema penevi sp. n. were revealed. The species are described, illustrated and their phylogenetic relationships discussed. The first species is most similar to Xiphinema parasimile and is a member of Xiphinema simile species complex. The phylogenetic reconstructions inferred from three molecular markers (18S, D2-D3 28S rDNA and cox1) showed that Xiphinema penevi sp. n. is part of Xiphinema pachtaicum-subgroup and is closely related to Xiphinema incertum, Xiphinema pachtaicum, Xiphinema parapachydermum, Xiphinema plesiopachtaicum, Xiphinema astaregiense and Xiphinema pachydermum. Also, a separate “Xiphinema simile-subgroup”, outside the Xiphinema pachtaicum-subgroup and so far consisting only of the parthenogenetic species Xiphinema simile, Xiphinema parasimile, Xiphinema browni sp. n. and probably Xiphinema vallense was formed. New primers for amplification and sequencing of part of the nad4 mitochondrial gene were designed and used.

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

Abstract 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.

Diversity of endosymbiont bacteria associated with a non-filarial nematode group

There is a significant knowledge gap with regard to non-filarial nematodes and their relationships, if any, with intracellular bacteria, with only sporadic reports in the literature. An intracellular bacteria Xiphinematobacter , belonging to subdivision 2 of the Verrucomicrobia, was previously reported in the ovaries of three species of the non-filarial Xiphinema americanum -group of nematodes. We explored the diversity of Xiphinematobacter in 22 populations of X. americanum sourced from six continents and conservatively have identified nine phylotypes, six of which have not previously been reported. A geographic basis to the phylotypes was noted with phylotypes A and B only found in Europe, whereas phylotypes F, G, H and I were mainly found in North America. Phylotypes C, D and E showed greater geographical variation. Sequences of Xiphinematobacter from this study help to inform the taxonomy of Verrucomicrobia such that the status and composition of Verrucomicrobia subdivision 2 potentially requires reflection.

Longidoridae and nepoviruses in Bulgaria and Slovenia

SummaryData on the distribution of Longidoridae and nepoviruses in Bulgaria and Slovenia are summarized. Six species of Longidorus (L. apulus, L. attenuatus, L. arthensis, L. fasciatus, L. elongatus, L. macrosoma), one Paralongidorus species (P. maximus) and three Xiphinema species (X. diversicaudatum, X. index, X. rivesi) are known as natural vectors of nine nepoviruses in Europe. Currently, 10 and 13 species of Xiphinema; 6 and 15 of Longidorus are reported to occur in Slovenia and Bulgaria, respectively. Paralongidorus maximus has been reported only in Bulgaria. Among the virus vector species X. index, X. diversicaudatum and L. elongatus occur in both countries, X. rivesi only in Slovenia and L. attenuatus, L. macrosoma, X. italiae and P. maximus only in Bulgaria. A report of X. index and Grapevine fanleaf virus (GFLV) in Bulgaria was related to transgenic grape tolerance to the same virus. Nepoviruses have been reported from Slovenia, but despite an evident relationship in the occurrence of GFLV and X. index in several vineyards the only laboratory proven transmission is that of TRSV and ToRSV to bait plants by a Slovenian population of X. rivesi.

Morphological characterisation and diagnostics of Xiphinema non-americanum group species (Nematoda: Longidoridae) from Romania using mutiplex PCR

SummaryAdditional data on the occurrence and distribution of Xiphinema non-americanum group species in Romania are provided. Xiphinema diversicaudatum, X. index, X. vuittenezi and X. italiae were recovered from vineyards and cherry fruit trees; adults and juvenile stages were described and analysed and the morphology/variability discussed. Multiplex PCR diagnostic test using species-specific primers designed by Wang et al. (2003) yielded amplification products with expected lengths for all screened populations of these four species. Two ribosomal markers (D2-D3 28 LSU rDNA and ITS) were sequenced and ITS RFLP patterns were obtained from two X. vuittenezi populations, which have shown some morphological differences. Comparatively low level of interpopulation genetic dissimilarity (<1 %) was revealed for both markers (for D2D3 — 0.5 %; for ITS — 0.7 %). Both populations of X. vuittenezi studied produced identical ITS-RFLP specific pattern that clearly identify this species.

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

Abstract A new needle nematode, Longidorus carniolensis sp. 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 carniolensis sp. n. with other Longidorus species based on analysis of this DNA fragment and morphology are discussed.

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

Abstract The taxonomic position of two antarctic dorylaimid species Amblydorylaimus isokaryon (Loof, 1975) Andrássy, 1998 and Pararhyssocolpus paradoxus (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 Pararhyssocolpus paradoxus gen. n., comb. n. (=Rhyssocolpus paradoxus) previously regarded as a member of Nordiidae or Qudsianematidae, showed distant relationship both to Rhyssocolpus vinciguerrae and Eudorylaimus spp. The phylogram inferred from 28S sequences revealed that Amblydorylaimus isokaryon is a member of a well-supported group comprised of several Aporcelaimellus spp., while, no close relationships could be revealed for the Pararhyssocolpus paradoxus gen. n., comb. n. to any nematode genus. On the basis of molecular data and morphological characteristics, some taxonomic changes are proposed. Amblydorylaimus isokaryon is transferred from family Qudsianematidae to family Aporcelaimidae, and a new monotypic genus Pararhyssocolpus gen. n. is proposed, attributed to Pararhyssocolpidae fam. 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.

Morphological and molecular characterisation of Xiphinema macroacanthum Lamberti, Roca & Agostinelli, 1989 (Nematoda: Longidoridae) from olive orchards in southern Italy

A population of Xiphinema macroacanthum Lamberti, Roca & Agostinelli, 1989 originating from olive orchards in Brindisi, Italy and containing both adults and all juvenile stages, is described and illustrated. The first juvenile stage is reported for the first time. Molecular characterisation of this species, using the D2–D3 expansion domains of the 28S rDNA and ITS region, was carried out. PCR–RFLP analyses of the ribosomal gene regions determined species-specific patterns that clearly differentiate X. macroacanthum. Sequences of the D2–D3 domains and the partial 18S-ITS1 rRNA genes were analysed using several methods for inferring phylogeny to reconstruct the relationships between X. macroacanthum and other Xiphinema species.

Nematode assemblages from Mountain Pine (Pinus mugo Turra) communities in Pirin Mountain, Bulgaria.

SummaryThe structural and functional diversity of nematode communities from Pinus mugo sites in Pirin Mountain was assessed. The sampling plots represent different levels of disturbance — next to and outside ski runs. Nematode assemblages from this habitat can be characterised with high diversity (in total, 104 taxa and richness ranging from 41 to 65 genera per site). In general, the trophic structure was dominated by omnivorous and bacterial feeders coupled with low proportion of plant feeding nematodes. The high values of Maturity indices and the results from faunal analysis indicate relatively stable environment and undisturbed conditions for all sites. No clear correlation between the nematode assemblages’ characteristics and the level of disturbance (position of the site in relation to ski runs) was revealed.