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<p><i>Helicotylenchus fortuneri</i> n. sp. was recovered from the rhizosphere of an almond tree in the Bushehr province, southern Iran. It was described and illustrated herein based upon morphological characteristics, utilizing both light and scanning electron microscopy (SEM) and morphometric data. The molecular phylogenetic analyses were performed using sequences of the partial small subunit (SSU) and D2-D3 expansion segments of the large subunit (LSU) ribosomal DNA, as well as the cytochrome c oxidase subunit I (<i>COI</i> mtDNA) gene. <i>Helicotylenchus fortuneri</i> n. sp. is characterized by an open J, to open C-shaped females body, 471 − 765 µm long, rounded cephalic region with four annuli, four lines in the lateral field, stylet 19.7 − 23.0 µm long, its knobs slightly inclined backward, vulva at 67.3 − 77.9% of the body, posterior genital branch reduced, forming a postvulval uterine sac (PUS), female tail variable in shape and males present. It was morphologically compared with <i>H. brevis</i>, <i>H. delanus</i>, <i>H. intermedius</i> and <i>H. valdeclarus</i>; and their morphological differences were discussed. In the inferred SSU phylogeny using sequences of the relevant genera, the included sequences of <i>Helicotylenchus</i> formed a clade, and the sequences of the new species occupied a basal placement. The LSU phylogeny was performed in two ways. The first analysis constrained to the genus <i>Helicotylenchus</i> sequences as ingroups. In the second LSU analysis, sequences of <i>Helicotylenchus</i> plus sequences of representatives of the genera <i>Rotylenchus</i> and <i>Hoplolaimus</i> were also included. In the inferred tree using the second dataset, the currently available LSU sequences of <i>Helicotylenchus</i> appeared polyphyletic and the LSU sequences of the new species appeared as a lineage having unresolved relationships with other lineages. In the <i>COI</i> phylogeny using sequences of <i>Helicotylenchus</i> spp. and <i>Rotylenchus</i> spp., the included sequence of <i>Helicotylenchus</i> formed a monophyletic group and the relationships of the newly generated sequences of the new species with other sequences were not resolved due to polytomy. A compendium of traits helpful for mono-ovarian species delimitation was also provided.</p>

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Morphological and molecular description of Helicotylenchus fortuneri n. sp. (Hoplolaimidae: Hoplolaiminae) a new mono-ovarian species from Iran

  • 期刊论文

  • 发表日期：

    2025年10月24日

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  • Somayeh Mokhtari,
  • Fatemeh Bazeghi,
  • Alba N. Ruiz-Cuenca,
  • Juan E. Palomares-Rius,
  • Ali Eskandari,
  • Majid Pedram

摘要

Helicotylenchus fortuneri n. sp. was recovered from the rhizosphere of an almond tree in the Bushehr province, southern Iran. It was described and illustrated herein based upon morphological characteristics, utilizing both light and scanning electron microscopy (SEM) and morphometric data. The molecular phylogenetic analyses were performed using sequences of the partial small subunit (SSU) and D2-D3 expansion segments of the large subunit (LSU) ribosomal DNA, as well as the cytochrome c oxidase subunit I (COI mtDNA) gene. Helicotylenchus fortuneri n. sp. is characterized by an open J, to open C-shaped females body, 471 − 765 µm long, rounded cephalic region with four annuli, four lines in the lateral field, stylet 19.7 − 23.0 µm long, its knobs slightly inclined backward, vulva at 67.3 − 77.9% of the body, posterior genital branch reduced, forming a postvulval uterine sac (PUS), female tail variable in shape and males present. It was morphologically compared with H. brevis, H. delanus, H. intermedius and H. valdeclarus; and their morphological differences were discussed. In the inferred SSU phylogeny using sequences of the relevant genera, the included sequences of Helicotylenchus formed a clade, and the sequences of the new species occupied a basal placement. The LSU phylogeny was performed in two ways. The first analysis constrained to the genus Helicotylenchus sequences as ingroups. In the second LSU analysis, sequences of Helicotylenchus plus sequences of representatives of the genera Rotylenchus and Hoplolaimus were also included. In the inferred tree using the second dataset, the currently available LSU sequences of Helicotylenchus appeared polyphyletic and the LSU sequences of the new species appeared as a lineage having unresolved relationships with other lineages. In the COI phylogeny using sequences of Helicotylenchus spp. and Rotylenchus spp., the included sequence of Helicotylenchus formed a monophyletic group and the relationships of the newly generated sequences of the new species with other sequences were not resolved due to polytomy. A compendium of traits helpful for mono-ovarian species delimitation was also provided.