Rev 12/11/2019

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          Rhizonemella (Cid del Prado Vera, Lownsbery & Maggenti, 1983) Andrassy, 2007

The type (and only) species is R. sequoiae (see the species page for greater delail on life cycle and biology)


      Rhizonema Cid del Prado Vera, Lownsbery & Maggenti, 1983

Andrassy (2007) provided the nomen novum because the name Rhizonema was already in use in the Hydrozoa:: Rhizonema Clark (1877)

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Morphology and Anatomy:

Cystoid nematodes in which the body wall of the female does not harden into a cyst.


Female:  No cyst stage.  

Body globose, with prominent neck and terminal cone.  

Cuticle thick, wavy; entire body annulated, except terminal cone. 

D-layer absent.  No subcrystalline layer.

Vulva and anus situated on terminal cone which has a thickened cuticle.  

Phasmids not observed.  

Eggs retained in female body together with hatched second-stage juveniles.  



Body size range for the species of this genus in the database - Click:
Males:  Body twisted.  

Lateral field with four lines.

Spicules nearly straight, pointed, posteriorly directed.

Cloacal tube well developed.

No phasmids.  

Second-stage juveniles: Lateral field with four lines. 

Esophageal glands filling body cavity.  

Tail conical-pointed, with long, hyaline, terminal part. 

Phasmids with lens-like structure.  

[Ref: Luc, Maggenti & Fortuner,  (1988).]

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Economic Importance:


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Nurse cell system: A single, giant cell with a giant nucleus.      

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

For Ecophysiological Parameters for this genus, click 

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Andrassy, I. 2007. Free-living Nematodes of Hungary Vol II.Hungarian Natural History Museum, Budapest. 496p.

Cid del Prado Vera, and B. F. Lownsbery. 1984. Histopathology and host range studies of the redwood nematode Rhizonema sequoiae. Journal of Nematology 16:68-72.

Cid Del Prado Vera, I., B. F. Lownsbery and A. R. Maggenti. 1983. Rhizonema sequoiae n. gen. n. sp. from coast redwood Sequoia sempervirens (D. Don) Endl. Journal of Nematology 15:460-467.

Luc, Maggenti & Fortuner, Rev. Nematol. 11(2):159-176 (1988).

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Copyright © 1999 by Howard Ferris.
Revised: December 11, 2019.