Rev 09/13/2023

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            Paralongidorus  Siddiqi, Hooper and Khan, 1963

Type species of the genus: Paralongidorus sali  Siddiqi, Hooper and Khan, 1963

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Morphology and Anatomy:

Large to very large nematodes, up to 12 mm.


  • Labial region narrow and continuous with body contour.
  • Odontostyle is long, connected to lining of cheilostome by a cuticular membrane that becomes variously folded, with refractory qualities - the "guiding ring."  Position  of guiding ring is diagnostic.  
  • Stylet extension (odontophore) not flanged.  
  • Opening of amphid is slit-like in Paralongidorus and pore-like in Longidorus.
  • Among the longest plant-parasitic nematodes.

Close to 100 species of Paralongidorus have been described.  However,there is much overlap in diagnostic characters and in the ranges of morphometric data.  Consequently, step-wise dichotomous keys based on morphology and morphometrics have been difficult to construct.  The combination of molecular and morphological data will help resolve species diagnostics (Palomares-Rius et al., 2013).  Of course, molecular adata are not currently available for many of the nominal species.  A polytomous key, where multuiple morphometric and morphological charaters are considered simultaneously will be useful in this and other nematode genera.  As an example, Escuer and Arias (1`997) showed differences (and similarities) among 70 nominal species of Paralongidorus using a polytomous key.

Body size range for the species of this genus in the database - Click:
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Several species recorded from Asia and Africa, ocasionally from Europe; rarely from the Americas. Actually, Paralongidorus appears to be distributed worldwide, occurring on every continent with the exception of Antarctica.

The greatest biodiversity of the genus occurs in Asia, where 26 species have been reported from several countries, followed by Africa with 22 reported species.  In other continents the diversity of the genus is lower: Europe, with eight reported species, Oceania with three species, and North and South America with only one species each.. The species distribution data are considered to support the hypothesis that the probable origin of Paralongidorusis is in the region of South-East Africa to India (Palomares-Rius et al., 2008).

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Economic Importance:

C-rated pests in California Nematode Pest Rating System.

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 Migratory ectoparasites of plant roots.    

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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 

Relatively little critical biological and ecological work done on this important genus - some species are difficult to work with. 


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Feeding causes direct damage to plant roots and some species are also vectors of pathogenic plant viruses (Decraemer and Robbins, 2007).

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Coomans A.A. and W, Decraemer, 2007. Revision of some species of the genus Paralongidorus sensu Siddiqi et al. (1993), with a discussion on the relationships within the family Longidoridae (Nematoda: Dorylaimida). Nematology 9:643-662.

Decraemer, W, and Robbins, R.T. 2007.  The who, what and where of Longidoridae and Trichodoridae.  J. Nematology 39:295-297.

Escuer, M. and Arias, M. 1997. Paralongidorus iberis sp.n. and P. monegrensis sp.n. from Spain with a polytomous key to the species of the genus Paralongidorus Siddiqi, Hooper & Khan, 1963 (Nematoda : Longidoridae). Fundamental and Applied Nematology 20:135-148.

Palomares-Rius, J.E., Subbotin, S.A., Landa, B.B.,Volvas, N., and Castillo, P. 2008. Description and molecular characterisation of Paralongidorus litoralis sp. n. and P. paramaximus Heyns, 1965 (Nematoda: Longidoridae) from Spain. Nematology 10:87-101.

Palomares-Rius, J.E., Cantalapiedra-Navarette, C., Gutierrez-Gutierrez, C., Liebanas, G., Castillo, P. 2013. Morphological and molecular characterisation of Paralongidorus plesioepikimis n.sp. (Nematoda: Longidoridae) from southerrn Spain. Nematology 15:363-378.

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Copyright © 1999 by Howard Ferris.
Revised: September 13, 2023.