Malenchus geraerti




Rev 04/03/2023

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           Malenchus geraerti Pedram, Soleymanzadeh, Pourjam & Mobasserim, 2018.



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Morphology and Anatomy:


Refer to subfamily diagnosis (Tylenchinae)

  • Body slightly ventrally curved, narrowing from the level of vulva to tail.

  • Cuticle coarsely annulated, annuli 2.1–2.3 µm wide at mid-body.

  • Lateral field a plain band with two incisures, raised in cross section.

  •  Lip region continuous with body contour, with bearing 3–4 annuli.

  • Amphidial openings S-shaped slits, starting from labial plate, extending posteriorly, markedly narrowing and reaching base of the head.

  • Cephalic framework weakly sclerotized.

  • Stylet shaft moderately developed, conus finer, knobs directed posteriorly.

  • Dorsal gland orifice (DEGO) close to stylet knobs.

  • Excretory pore at level of esophageal bulb.

  • Esophagus with slender procorpus, muscular, rounded to ellipsoid metacorpus with well-developed valve, slender isthmus and saccate pharyngeal bulb .

  •  Tail in both sexes conical, tapering gradually to a more or less pointed tip.

  • Females:

  • Mono-prodelphic, ovary outstretched, oocytes mostly in single file, oviduct short, spermatheca elongate-rounded, filled with small spheroid sperm cells, offset and sometimes appearing as bilobed  crustaformeria and uterus not clearly discernible from each other.
  • Vagina perpendicular to body axis, with moderately sclerotized walls.
  • Small, undifferentiated postvulval uterine sac (PUS) present.
  • Vulva sunken into body,  a transverse slit, with large epiptygma and no flaps.
  • Vulva–anus distance  0.8–1.1 times the tail length.



  •  About half as frequent as females.
  •  Testis single, outstretched.
  • Spicules tylenchoid, narrow and slender, slightly arcuate distally.
  •  Gubernaculum small.
  •  Bursa cloacal with smooth margin.


Ref: Pedram et al., 2018

Reported median body size for this species (Length mm; width micrometers; weight micrograms) - Click:

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Described from forest soils in northern Iran.

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Economic Importance:


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For an extensive host range list for this species, click


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Life Cycle:

Ecophysiological Parameters:

For Ecophysiological Parameters for this species, click If species level data are not available, click for genus level parameters


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Host Plant Resistance, Non-hosts and Crop Rotation alternatives:

For plants reported to have some level of resistance to this species, click



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Geraert, E. 2008. The Tylenchidae of the World. Identification of the Family Tylenchidae (Nematoda). Ghent, Belgium, Akademia Press

Geraert & Raski, (1987) Rev. Nematol. 10(2):143-161.

Khera, S., Zuckermann, B.M. (1963). In vitro studies of host-parasite relationships of some plant-parasitic nematodes, Nematologica, 9, 1-6.

Pedram, M., Soleymanzadeh, M., Pourjam, E., Mobasserim, M. 2018. Observations on Malenchus geraerti n. sp. (Rhabditida: Tylenchidae), a morphological and molecular phylogenetic study. Zootaxa 4369:406-418.

Qing, X., S�nchez-Monge, A., Janssen, T., Couvreur, M. and Bert, W. 2016. Description of Malenchus sexlineatus n. sp., new records of three known species of Malenchus Andrassy, 1968 (Nematoda: Tylenchidae) and notes on amphidial aperture development. Nematology 18:155-174.

Qing, X., Bert, W. 2017. Redefinition of Genus Malenchus Andrassy, 1968 (Tylenchomorpha: Tylenchidae) with Additional Data on Ecology. J. Nematology 49:189-206.

Siddiqi, M.R. 2000. Tylenchida. Parasites of Plants and Insects, 2nd edition. Wallingford, UK, CAB International,


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