Zygotylenchus Guevarai Research Articles

Plant-parasitic nematodes associated with cultivated and wild olive trees in Crete, Greece

Summary The present study is part of a survey for the identification of plant-parasitic nematodes in the rhizosphere of cultivated and wild olive trees in Crete, Greece. Sixteen species corresponding to 13 genera are added to 20 species belonging to 8 genera, previously reported in the survey. Seven nematode species, Filenchus ditissimus, Filenchus vulgaris, Ogma civellae, Pratylenchoides crenicauda, Psilenchus hilarulus, Tylenchus elegans, and Zygotylenchus guevarai, are recorded for the first time in Greece.

Molecular and phylogenetic studies on Pratylenchidae from Iran with additional data on Pratylenchus delattrei, Pratylenchoides alkani and two unknown species of Hirschmanniella and Pratylenchus

Thirteen species of Pratylenchidae: Pratylenchus coffeae, P. delattrei, P. loosi, P. neglectus, P. penetrans, P. pseudopratensis, P. thornei, P. vulnus, Pratylenchus sp., Pratylenchoides alkani, P. ritteri, Hirschmanniella sp. and Zygotylenchus guevarai were collected from different crops and plants throughout Iran. The specimens were identified using morphological and molecular methods. Morphometrics and morphology are given for Pratylenchus sp., P. delattrei, Pratylenchoides alkani and Hirschmanniella sp. The D2-D3 expansion segments of the 28S rRNA gene were amplified and sequenced for all 13 species studied. Diagnostic PCR-ITS-RFLP profiles are given for Pratylenchus delattrei, P. penetrans, P. pseudopratensis, Pratylenchus sp., Pratylenchoides alkani and P. ritteri. Pratylenchus neglectus and P. thornei, collected from cereal fields, P. loosi from tea plantations, P. coffeae from banana, P. penetrans from ornamental plants, P. vulnus from pines and Z. guevarai from almonds showed a high level of similarity in the D2-D3 sequences with corresponding GenBank sequences. Nucleotide differences between Iranian populations and reference species were in the intraspecific range. Pratylenchus delattrei, found in vegetable fields, and Pratylenchus sp. from palm rhizosphere, formed a highly supported clade with P. zeae, the two former species being morphologically very close to the latter except in tail shape. Pratylenchus pseudopratensis, from cereal fields, clustered with P. vulnus with low support. Phylogenetic relationships within Pratylenchus species were mainly congruent with those obtained in previous studies. Despite the morphological similarities between P. ritteri and P. alkani, the D2-D3 of 28S rRNA gene sequences differed by 5 bp. Hirschmanniella sp., from a rice field, formed a clade with H. loofi and H. kwazuna.

Description of Pratylenchus hispaniensis n. sp. from Spain and considerations on the phylogenetic relationship among selected genera in the family Pratylenchidae

AbstractA new amphimictic species, Pratylenchus hispaniensis n. sp., parasitising the roots of gum cistus in Andújar (Jaén), southern Spain, is described. The new species is characterised by the presence of numerous males and by the female having a lip region with three annuli, a divided face, a robust stylet (14.5-17.0 μm) with rounded knobs, lateral fields with four lines, V = 80-84, a round spermatheca full of sperm, well developed post-vulval uterine sac and an obliquely truncate tail with irregularly annulated terminus. Morphologically this species is related to P. bhatti, P. kralli, P. mediterraneus, P. pseudofallax and P. thornei. A phenetic study of the 25 most useful diagnostic morphological and allometric characters for Pratylenchus species was done using multivariate factor and linear discriminant analyses. In the factor analysis the first seven factors accounted for 71.1% of the total variance of the characters selected. These factors were related to female tail, pharyngeal overlap, reproductive behaviour, stylet length, L/post-vulval uterine sac ratio, body length and number of lip annuli. Discriminant analysis differentiated Pratylenchus spp. from the three valid species of Zygotylenchus. The results of the phylogenetic analysis based on sequences of the D2-D3 expansion regions of 28S, partial 18S and ITS rRNA genes confirmed the close relationship of P. hispaniensis n. sp. with P. mediterraneus and inferred molecular affinity with P. brzeskii, P. neglectus and P. thornei, in spite of variation in the position of P. hispaniensis n. sp. in the clades. Additional phylogenetic analyses based on the same sets of sequences for P. hispaniensis n. sp., Zygotylenchus guevarai and other Pratylenchidae indicated that Pratylenchus includes several paraphyletic lineages; however, likelihood tests did not reject monophyly of the genus. The inclusion of Pratylenchus, Zygotylenchus, Hirschmanniella, Nacobbus and Apratylenchus in Pratylenchidae was supported.

Nematodes associated with vineyards throughout Markazi Province (Arak), Iran

In a survey conducted from April 2008 through October 2008, 21 nematode species were found associated with grapes in Markazi Province, Iran. These included: Aphelenchus avenae, Aphelenchoides limberi, Boleodorus thylactus, Criconema mutabile, Mesocriconema xenoplax, Ditylenchus myceliophagus, Irantylenchus clavidorus, Helicotylenchus digonicus, H. vulgaris, H. crenacauda, H. pseudorobustus, Hemicriconemoides mangiferae, Meloidogyne javanica, Geocenamous brevidens, G. rugosus, Pratylenchus neglectus, P. thornei, P. ritteri, Tylenchulus semipenetrans, Xiphinema index and Zygotylenchus guevarai. Populations varied in their frequency and distribution among surveyed vineyards but Helicotylenchus spp. and Pratylenchus spp. were the most commonly observed genera. Meloidogyne spp. and Xiphinema spp. were rarely encountered during the survey. This is the first reported province-wide nematode survey of grapes in Iran. Morphological and morphometric variations that typified the survey populations are given and discussed for certain nematode species.

Comparative morpho-anatomical studies of the female gonoduct within the Pratylenchidae (Nematoda: Tylenchina)

AbstractThe cellular morphology of the gonoduct of six Pratylenchus species, three Pratylenchoides species, Radopholus similis, Zygotylenchus guevarai, Hirschmanniella loofi and Nacobbus aberrans was revealed by dissection and light microscopy. Except for Nacobbus aberrans, all studied species show an overall similarity in gonoduct construction, i.e., an ovary often ending with a ring of cells, an oviduct formed from two rows of four cells and a 12-celled spermatheca followed by a tricolumella containing 16-24 cells. Pratylenchoides magnicauda and Z. guevarai did not diverge from the other Pratylenchidae in this respect, although their gonoduct differs from that of Amplimerlinius and Meloidogyne, both formerly postulated as related genera. The spermatheca structure observed in N. aberrans has not been reported elsewhere in the Nematoda, although the uterus is similar to that reported within the Heteroderinae and Meloidogyninae and the uterus comprises more than 300 cells, enlarging from a tricolumella to a polycolumella. Transmission electron microscopy of Z. guevarai revealed details of the cytoplasmatic contact between epithelial cells and the germ cells; a finger-like ovarian wall cell extension was found penetrating the oocyte. The oviduct lacks a preformed lumen and comprises eight cells with highly plicated cell membranes. The spermatheca is constructed from flattened wall cells and is followed by columnar uterus cells where evidence of eggshell formation was demonstrated.

Plant parasitic nematodes associated with six subtropical crops in New Zealand

The plant parasitic nematode fauna was examined from the soil and roots of six subtropical crops. Six nematode species not previously reported in New Zealand were discovered: Criconema annuliferum (de Man, 1921) Micoletzky, 1925; Crossonema civellae (Steiner, 1949) Mehta & Raski, 1971; Helicotylenchus paraplatyurus Siddiqi, 1972; Paratylenchus elachistus Steiner, 1949; Scutellonema brachyurus (Steiner, 1949) Andrassy, 1958; and Zygotylenchus guevarai (Tobar Jimenez, 1963) Braun & Loof, 1966. Six pest: host relationships, not previously recorded in New Zealand, are proposed: Pratylenchus crenatus on the hosts Passiflora edulis and Cyphomandra betaceae, Pratylenchus penetrans and Zygotylenchus guevarai on P. edulis, Tylenchulus semipenetrans on Diospyros kaki, and Meloidogyne hapla on Persea americana.

The first record of the root‐endoparasitic nematode Zygotylenchus guevarai in Britain

SUMMARYThe root‐endoparasitic nematode Zygotylenchus guevarai is recorded for the first time in Britain. It occurred in soil from a crop of glasshouse grown Alstroemeria in West Sussex, England.