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The host suitability of alfalfa, barley, cantaloupe, cowpea, cucumber, maize, millet, rapeseed, spinach, squash, sugar beet, tomato and wheat to Scutylenchus rugosus was evaluated under glasshouse and outdoor conditions. The results showed that reproduction factor (Rf) of the nematode on wheat and barley was higher than 2.4 and on maize hybrids (SC 704 and MV 524), spinach and alfalfa Rf was between 0.9-2.1. In two other experiments, the effects of field populations of S. rugosus on growth of three Iranian wheat cultivars and three maize hybrids were investigated. The results showed that the nematode had significant negative effects on growth parameters of the plants. Wheat cultivars were more suitable hosts and Rf of the nematode on them was significantly higher than on the maize hybrids.

In: Nematology

Summary

The ectoparasitic nematode, Scutylenchus rugosus, is common in Europe and Asia, feeding on several plant species and limiting productivity. Its seasonal population fluctuation was monitored on maize and wheat crops, in glasshouse and open field conditions, respectively. Its survival in the absence of a host plant was also investigated in a microplot field trial. The population of S. rugosus increased gradually during 4 months of maize growth in glasshouse conditions, and more than 50% increase occurred during the second month after sowing. Under wheat growth, in open field conditions, the lowest population was observed during July, 1 month after wheat harvesting, and the highest in August, after the first post-harvest irrigation. About 50% of the nematode population survived after a 5-month period of drought in the absence of a host and the percentage of surviving nematodes was greater under a dry soil regime than under a dry-wet regime. Most of the inactive S. rugosus were adults. After 24 h of soil wetting, most inactive nematodes resumed their activity and the optimum temperature for activation was 25°C.

In: Nematology

Summary

The Persian sessile nematode (Cacopaurus pestis) and pin nematodes (Paratylenchus spp.) are sedentary ectoparasitic nematodes associated with many plant species worldwide. In this study, we provide morphological and molecular characterisation of seven populations of C. pestis and eight species of Paratylenchus recovered from north-western Iran. A total of 26 new sequences of D2-D3 expansion segments of 28S rRNA and ITS rRNA were obtained and used to reconstruct phylogenetic trees. Results of phylogenetic analyses revealed that the subfamilies of Tylenchulidae form well-separated clades, but that the genera Cacopaurus and Paratylenchus (= Gracilacus) in the subfamily Paratylenchinae are clustered in one clade. It appears that the previously used character of “stylet length greater than 40 μm” is not homologous and evolved more than once within the Paratylenchinae.

In: Nematology

Summary

Helicotylenchus ciceri n. sp. and H. scoticus are described and illustrated based on morphological, morphometric and molecular characters. The new species is characterised by a conical and truncated lip region with five or six distinct annuli, stylet 32-37 μm long with anteriorly concave knobs, secretory-excretory pore posterior to the pharyngo-intestinal valve, dorsally convex-conoid tail with a terminal projection, phasmids 14 (7-20) annuli anterior to the level of anus, empty spermatheca and absence of males. Intraspecific variation of 16 populations of H. scoticus, collected from chickpea and lentil fields in Kermanshah province, western Iran, is discussed. The results of the phylogenetic analyses based on the sequences of the partial 18S rRNA, D2-D3 expansion segments of 28S rRNA and ITS rRNA genes are provided for the studied species, confirming their differences from each other and determining the position of them and their relationships with closely related species.

In: Nematology

Abstract

During a survey of plant-parasitic nematodes associated with walnut trees in Hamadan province, west Iran, several species of Longidoridae and infraorder Tylenchomorpha, including Paratylenchus paraperaticus sp. n., were identified. Paratylenchus paraperaticus sp. n. is characterised by its small size (255-385 μm), young female vermiform and ventrally curved, older female obese, swollen in prevulvar region and J- or W-shaped; truncate conical head with distinct and laterally protruding submedian lobes; long and flexible stylet (75.0-96.5 μm); body cuticle with fine and smooth annuli in young females, but in older females ornamented with minute reflective tubercles or irregularities that are confined mostly to the neck region; lateral field with four lines; presence of lateral vulval flaps; rounded to ovoid spermatheca filled with small, rounded sperm; and conical and ventrally curved tail with pointed to finely rounded terminus.

In: Nematology

The genus Pratylenchoides has recently been transferred from the family Pratylenchidae to Merliniidae. To investigate further the relationship between these ‘Pratylenchus-like’ species (residing in the subfamily Pratylenchoidinae) and the subfamily Merliniinae, more than 500 soil samples were collected from various natural and agronomic habitats in the northern and north-western provinces of Iran. In this study, paratypes or populations of 22 species of Pratylenchoides, including the Iranian populations of P. alkani, P. crenicauda, P. erzurumensis, P. laticauda, P. nevadensis, P. ritteri and an undescribed species, were studied. Intra- and interspecies variation of the following characters were investigated: position of the pharyngeal gland nuclei, shape of female and male head, striation of female tail terminus, number of lateral lines at mid-body and in phasmid region for females, presence of intestinal fasciculi, and shape of sperm. Combining morphological and molecular data prompted us to propose two clusters of related Pratylenchoides species. One cluster includes P. crenicauda, P. variabilis and P. erzurumensis, whereas the second cluster consists of P. alkani, P. nevadensis and P. ritteri. Our data point to a sister positioning of P. magnicauda vis-à-vis all Pratylenchoides species included in this research. Analyses of SSU rDNA (for family and subfamily relationships) and partial LSU rDNA sequences (for intrageneric relationships) data revealed: i) the distal and nested positioning of all Pratylenchoidinae within the Merliniidae; ii) the single transition from ectoparasitism to migratory endoparasitism within the family Merliniidae corresponds with the current subfamily partitioning; and iii) support for the monophyletic nature of the genus Pratylenchoides.

In: Nematology

Devibursaphelenchus kheirii sp. n. is described and illustrated based on morphological, morphometric and molecular data. The new species is characterised by females with 370-472 μm body length, lip region separated from the body by a shallow constriction, three lines in lateral field, stylet short, 13.5-15.0 μm long, lacking basal knobs or swellings, excretory pore posterior to metacorpus, vulval flap absent, post-uterine sac short, without sperm, rectum and anus obscure, posterior end of the body elongate-conoid with finely rounded terminus. Males of the new species are characterised by their tail ventrally curved after fixation, having two pairs of caudal papillae, spicules 9-11 μm long with an elongated condylus, with rounded tip, pointed rostrum, lacking cucullus and having small conical terminal bursa. The new species comes close to D. hunanensis, D. lini and D. wangi. Beside morphological comparisons, the molecular phylogenetic analyses based on 778 bp of partial sequences of 28S rDNA D2-D3 were performed using two Bayesian inference (BI) and maximum likelihood (ML) methods and revealed that D. kheirii sp. n. formed a clade with the remaining species of the genus and one species of Ektaphelenchoides. This is the first report on occurrence of the genus Devibursaphelenchus in Iran. Devibursaphelenchus eproctatus syn. n. is proposed as a junior synonym of D. hunanensis.

In: Nematology

Ektaphelenchoides caspiensis n. sp. is described and illustrated based on morphological, morphometric and molecular characters. The new species is characterised by its continuous lip region, obscure lateral field, females with body length of 499-572 μm, 9-10 μm long stylet, excretory pore posterior to base of metacorpus at 62-72 μm from anterior body end, short post-uterine sac ca 0.5 times corresponding body diam. or 4-9 μm long, and posterior body end (i.e., including ‘tail’) very long and filiform. Males are common and have 7-8 μm long spicules, five copulatory papillae and a long (109-140 μm) conoid tail with very long filiform terminus. Based on morphological and molecular characters, it comes close to five known species of the genus, namely: E. attenuata, E. fuchsi, E. kelardashtensis, E. musae and E. ruehmi. It differs from the closest species, E. kelardashtensis, by the shorter female stylet (9-10 vs 13-16 μm), more anterior vulva (V = 51.7-58.1 vs 61.5-68.0), more posterior excretory pore (62-72 vs 55-66 μm from anterior end), very long posterior body (i.e., including ‘tail’) in female, and male tail shape (conoid with very long filiform terminus vs conoid, sharply pointed). Comparisons with other close species of the genus are also discussed. Molecular analyses were performed using 732 bp of the partial ribosomal RNA large subunit gene (D2-D3 of LSU) using Bayesian inference (BI) and maximum likelihood (ML) methods and showed that the new species formed a clade with one species of the genus (E. fuchsi) and Devibursaphelenchus lini.

In: Nematology

Sixteen species, Amplimerlinius globigerus, A. macrurus, Bitylenchus parvus, Merlinius brevidens, M. nanus, Neodolichorhynchus phaseoli, Paramerlinius neohexagrammus, Pratylenchoides alkani, P. ritteri, P. utahensis, Scutylenchus paniculoides, S. rugosus, S. tartuensis, Scutylenchus sp. A, Trophurus impar and Tylenchorhynchus brassicae, from the families Telotylenchidae and Merliniidae were collected from different locations in Iran and molecularly characterised using sequencing of the D2D3 expansion fragments of the 28S rRNA gene. Morphometrics and light micrography for studied species are also provided as vouchers. The phylogenetic relationships of Telotylenchidae and Merliniidae with other representatives of the order Tylenchida, as obtained from Bayesian inference and Maximum likelihood analysis of partial 28S rRNA gene sequences, are presented and discussed. The results of phylogenetic analysis were in accordance with classifications in which Bitylenchus and Scutylenchus are considered as separate genera, but Tessellus and Telotylenchus were synonyms of Tylenchorhynchus. The Shimodaira-Hasegawa test of the 28S rRNA gene sequence alignment and trees rejected a large genus concept of Tylenchorhynchus and the constrained monophyly for Belonolaimidae revealed within this family two genera groups: iBelonolaimus and Ibipora; and iiCarphodorus and Morulaimus. The present results also support the combination of Pratylenchoides and Merliniinae into a single family, the Merliniidae.

In: Nematology

Abstract

Xiphinema iranicum n. sp. is described from soil samples collected about the rhizosphere of Rosa sp. growing in a natural mountainous region close to Maragheh city, north-western Iran. The new species belongs to group 6 of the polytomous key to species identification and is unique by having a medium body length (3.8-4.3 mm), odontostyle length of 141-162 μm, odontophore length of 90-98 μm, mid-body diam. of 69-88 μm, presence of spines in the uterus and a hemispherical to conoid tail with a rounded terminus or minute bulge. It resembles X. ingens, X. aceri, X. aequum, X. smoliki, X. illyricum, X. macedonicum and X. vuittenezi but differs from X. aceri and X. aequum by having different tail shape, longer odontophore, lower ratio a, higher ratio c and lower ratio c′. Compared to X. ingens and X. smoliki, it differs by having lower ratio a, lower ratio b, spines in uterus vs crystalline bodies plus pseudo Z-organ in X. ingens and spines plus pseudo Z-organ in X. smoliki and also by the presence of rare males, and, finally, it can be distinguished from X. vuittenezi by body and odontostyle length, characters of juveniles and molecular differences. The new species has similar polytomous identification codes to X. illyricum and X. macedonicum but can be differentiated from both by longer body, higher ratio c, higher V, longer odontostyle and odontophore and larger body diam. at mid-body and anus level. Ribosomal gene 18S rDNA and ITS1 of X. iranicum n. sp., X. aceri, X. montenegrinum and X. macedonicum, all obtained from north-western Iran in the same survey, were sequenced to investigate the phylogenetic relationships with other sequenced Xiphinema species.

In: Nematology