Rotylenchus

 

Contents

 

Rev 01/11/2022

 spiral nematodes Classification Hosts
Morphology and Anatomy Life Cycle
Return to Rotylenchus Menu Economic Importance Damage
Distribution Management
Return to Hoplolaimidae Menu Feeding  References
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 Classification:

      Tylenchina
       Tylenchoidea
        Hoplolaimidae
         Hoplolaiminae

          Rotylenchus Filipjev, 1936

    Synonyms:
      Anguillulina (Rotylenchus) Filipjev, 1936
      Gottholdsteineria (Andrassy, 1958)
      Orientylus (Jairajpuri and Siddiqi, 1977)   
      Calvatylus (Jairajpuri and Siddiqi, 1977)
      Interrotylenchus (Eroshenko, 1984)
      Scutellonemoides (Eroshenko, 1984)
      Varotylus (Siddiqi, 1986)

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Morphology and Anatomy:

Morphological identification of the more than 92 nominal species of the genus is difficult due to the overlap in ranges of many morphometric characters. upplementary characters necessary in identification include (such as lip annulation, lip shape, lateral field areolation, body longitudinal striation, stylet length, dorsal pharyngeal gland outlet, pharyngeal gland overlap, tail shape, vulva position, presence of males and phasmid position) (Vovlas et al., 2008).

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Female:  Body spiral to C-shaped.  

Labial region offset or continuous with body contours, anteriorly rounded or flattened, generally annulated, with or without longitudinal striae on basal lip annule.  

Lateral field with four lines, with or without scattered transverse striae.  

Labial framework, stylet, and stylet knobs average-sized for the family; knobs with rounded to indented anterior surface.

Dorsal esophageal gland opening often very close to stylet (6 µm), but with tendency to posteriorly directed migration (up to 16 µm).  

Esophageal glands overlap intestine dorsally and laterally; dorsal gland more developed than subventral glands; intestine symmetrically arranged between the subventral glands.  

Two genital branches outstretched, equally developed; posterior branch rarely degenerated (diovarial, amphidelphic). 

Epiptygma (single or double) present.  

Tail short, hemispherical, rarely with small ventral projection.

Phasmids pore-like, small, near anus level.   (photomicrograph of Rotylenchus robustus from Half Moon Bay, California by I.A. Zasada)  

Female of Rotylenchus mintanus.Vovlas et al., 2008
A: esohageal region; B: stylet; C: whole body; D; lip region with oral disc; E: vulval region; F,G: tail region.
Drawings from Vovlas et al., 2008
Males: Caudal alae enveloping tail (peloderan), not lobed.  (photomicrograph of caudal alae and spicules of Rotylenchus robustus from Half Moon Bay, California by I.A.  Zasada)

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Secondary sexual dimorphism not marked; sometimes anterior part of male body slightly smaller than female.

[Ref: Fortuner, (1987).]

 

Body size range for the species of this genus in the database - Click:
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Distribution:


Six species of Rotylenchinae were identified from 5,451 soil samples from throughout Great Britain. 

Pararoylenchus ouensensis was found only from Jersey, Channel Islands, Rotylenchus pumilis and R. buxophilus were mainly restricted to southern England.  

Rotylenchus uniformis, R. goodeyi and R. robustus were found in a wide range of soil types but R. robustus preferred more moist, alkaline soils and was recorded at greater altitudes then R. goodeyi  (Boag and Neilson, 1996).

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Economic Importance:

D-rated pest in California Nematode Pest Rating System.

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Feeding:

 All known Rotylenchus species. are obligate plant parasites. They have a wide range of wild and cultivated host plants.They are migratory ectoparasites, generally feeding on outer layers of root cells  without entering the roots. Consequently, the damage they cause is usually limited to necrosis of those cells penetrated by stylet. Some of the species have longer stylets, including R. cazorlaensis,  R. magnus and R. robustus which penetratwe root tissues to greater depth, kill more cells and cause more extensive damage to the root (Vovlas et al., 2008).

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Hosts:

Roylenchus goodeyi was more often found associated with beech and Scots pine while R. robustus preferred bog myrtle, oak and hawthorn (Boag and Neilson, 1996).

For an extensive host range list for this genus, click
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Life Cycle:

For Ecophysiological Parameters for this genus, click 

At the population levels encountered there was no evidence of either inter- or intraspecific competition within or between either R. goodeyi or R. robustus  (Boag and Neilson, 1996).

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Damage:

All the known Rotylenchus spp. are obligate plant parasites of a wide range of wild and cultivated plants and are migratory ectoparasites that feed on the surface of roots. They ectoparasites do not enter the plant root; the damage they cause is usually limited to necrosis of those cells penetrated by the stylet. Species with longer stylets (such as Rotylenchus cazorlaensis, R. magnus magnus., R. magnus jaeni and R. robuG117s2.aspxstus 6) penetrate the tissues to greater depths and cause more extensive damage to the root. (Vovlas et al., 2008).

 

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Management:

 

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References:

Boag, B.and R. Neilson.  1996.  Distribution and ecology of Rotylenchus and Pararotylenchus (Nematoda: Hoplolaimidae) in Great Britain. Nematologica 42: 96-108.

Fortuner, R. 1987.  Rev. Nematol. 10:219-232.

Vovlas, N., Subbotin, S.A. Troccoli, A., Liebanas, G., Castillo, G. 2008. Molecular phylogeny of the genus Rotylenchus (Nematoda, Tylenchida) and description of a new species. Zoologica Scripta 37:521-537

 

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Copyright © 1999 by Howard Ferris.
Revised: January 11, 2022.