Description and molecular characterisation of Ditylenchus pedrami n. sp. (Rhabditida: Anguinidae) from Iran

Ditylenchus pedrami n. sp., recovered from the rhizospheric soil of date palm in Khuzestan province, southwest Iran, is described and illustrated based upon morphological and molecular data. The new species is characterised by having six lines in the lateral field, lip region smooth and continuous with body contour, stylet 9-11 μm long, median pharyngeal bulb oval with small valve, pharyngeal bulb offset from the intestine, V = 83.9 (80.2-88.1), conoid tail with a pointed, dull or rounded tip and males with 20.1 (17-24) μm long spicules. Morphologically, the new species comes close to D. africanus, D. anchilisposomus, D. australiae, D. clarus, D. clavicaudatus and D. parcevivens, mainly by having shared features like six lines in the lateral fields, stylet length and somewhat similar tail tip. The new species was also compared with D. stenurus and D. sarvarae, two species with close phylogenetic affinities to it. The phylogenetic relationships of the new species with representatives of the family Anguinidae were reconstructed and discussed using partial sequences of the small subunit, D2-D3 expansion segments of the large subunit, and internal transcribed spacer regions of ribosomal DNA (SSU, LSU D2-D3 and ITS rDNA) based on Bayesian inference (BI).

Characterization of Pterotylenchus cecidogenus in Desmodium ovalifolium cover crop from oil palm plantations in central Colombia

Until recently, the stem gall nematode Pterotylenchus cecidogenus was only registered in eastern Colombia. However, the disease has recently been observed in central Colombian oil palm plantations that use Desmodium ovalifolium as a cover crop. Soil, root, stem, and leaf samples were collected from D. ovalifolium. Plants showed foliar yellowing, leaf drying, and galls within stem nodes. Nematodes were identified, and the distribution, population density, and relative importance of different genera were determined. We performed morphometric and molecular identification of nematodes associated with gall symptoms. The D2-D3 segment of the large subunit-28S of ribosomal ribonucleic acid (RNA) and internal transcribed spacer (ITS) was sequenced, and phylogenetic analysis was performed. P. cecidogenus mainly occurred in the galls and to a lesser extent in the roots and soil. Nematodes were not found in leaf or inflorescence tissue. Morphological and morphometric data confirm the presence of P. cecidogenus in the stems of D. ovalifolium with gall symptoms. This study is the first to report deoxyribonucleic acid (DNA) sequences of P. cecidogenus. Based on D2-D3 and ITS partial sequences, P. cecidogenus is a sister species of the leaf-galling nematode Ditylenchus phyllobius (Sinm. Orrina phyllobia).

Molecular Characterization and Phylogeny of Ditylenchus weischeri from Cirsium arvense in the Prairie Provinces of Canada

Ditylenchus weischeri that parasitizes the weed Cirsium arvense (L.) Scop., 1772, (creeping thistle) was described in 2011 from Russia based on their morphology, ITS-RFLP analysis, and Hsp 90 gene sequence of a few individuals and one field collection of the plant. More recently, we found C. arvense parasitized by D. weischeri in the Prairie Provinces of Canada. Plant host preference for D. weischeri was also distinct from D. dipsaci (Kühn) Filipjev, 1936. In the current study, a comprehensive molecular analysis of many D. weischeri specimens from Canada is presented. Individuals from 41 C. arvense or yellow pea grain samples with seeds of C. arvense from the Prairie Provinces were sequenced for the internal transcribed spacer (ITS rDNA), large subunit (LSU) D2D3 28S rDNA, partial segment of small subunit (SSU) 18S rDNA, and the heat shock protein Hsp 90 gene. The analysis also included D. weischeri individuals from C. arvense from Russia and garlic with D. dipsaci from the Provinces of Ontario and Quebec in Canada. Available sequence data of Ditylenchus species retrieved from GenBank were used to phylogenetically position this species within the genus Ditylenchus . In all studied genes, several single-nucleotide polymorphisms between the Canadian D. weischeri and both Russian haplotype and individuals of D. weischeri from C. arvense from Russia were found. The sequences of ITS rDNA, LSU D2D3 28S rDNA, and Hsp 90 were used to construct separate dendrograms. For each of the three genes examined, D. weischeri was grouped separately from the other Ditylenchus . Ditylenchus samples from C. arvense was positioned to a single clade such as D. weischeri and distinct from D. dipsaci . With past reports of plant host preference and morphology, the results of this study provide further evidence for the fact that D. weischeri is distinct to be separated from D. dipsaci . Furthermore, minor differences in molecular divergence and morphology to the Russian haplotype and limited symptoms of disease on C. arvense in Prairie Canada suggest the Canadian and Russian populations of D. weischeri may be diverging.

Nothotylenchus andrassy n. sp. (Nematoda: Anguinidae) from Northern Iran

Nothotylenchus andrassy n. sp. is described and illustrated from moss ( Sphagnum sp.) based on morphology and molecular analyses. Morphologically, this new species is characterized by a medium body size, six incisures in the lateral fields, and a delicate stylet (8-9 µm long) with clearly defined knobs. Pharynx with fusiform, valveless, non-muscular and sometimes indistinct median bulb. Basal pharyngeal bulb elongated and offset from the intestine; a long post-vulval uterine sac (55% of vulva to anus distance); and elongate, conical tail with pointed tip. Nothotylenchus andrassy n. sp. is morphologically similar to five known species of the genus, namely Nothotylenchus geraerti , Nothotylenchus medians , Nothotylenchus affinis , Nothotylenchus buckleyi , and Nothotylenchus persicus . The results of molecular analysis of rRNA gene sequences, including the D2-D3 expansion region of 28S rRNA, internal transcribed spacer (ITS) rRNA and partial 18S rRNA gene are provide for the new species.