Rev: 07/28/2020

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           Criconema Hofmanner and Menzel, 1914

Andrassy (1979) observed that the genus Criconema, the type genus of Criconematidae, was based on the description of Criconema guernei which he considered species dubia because it was an inadequate description of a juvenile nematode. Thus the genus name Criconema is considered invalid and the species were transferred to Ogma Southern, 1914. However, more recently, Geraert (2010) accepts the valididity of the genus and retains the name Criconema Hofmanner and Menzel, 1914.

      Lobocriconema (De Grisse and Loof, 1965)
      Nothocriconema (De Grisse and Loof, 1965)
      Merocriconema (Raski and Pinochet, 1976)
      Nenocriconema (Darekar and Khan, 1981)
      Nothletus (Ebsary, 1981)
      Nothocriconemella (Ebsary, 1981)
      Paracriconema (Ebsary, 1981)
      Amphisbaenema (Orton Williams, 1982)
      Cerchnotocriconema (Bernard, 1982)

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Morphology and Anatomy:

Criconema murrayi: scanning electron micrograph.

From Clark and Stone, 1976.

Females: Body small to rather large (0.24 to 0.74 mm).  Short, plump, sluggish nematodes with spines and ornamentation on cuticle; 24-134 annulations.  

The various types of cuticular ornamentation are:
      1. finely crenate
      2. scale-like projections, if present, only on posterior part of body
      3. irregular, plate-like coverings on cuticle over entire body (C. sheperdae) or on part of annules (lamellatum)
      4. ruffled, ribbon-like ornamentation encircling annule on anterior surface (C. (giardi) guerni) or both anterior/posterior surfaces (psephinum)
      5. cuticular fringe extending from posterior margin of annules ( C. (giardi) guerni).

Labial region usually with six pseudo-lips, rounded and projecting forward from the first annule. Annuli of labial region smooth; usually with one annule wider and clearly set off from the next succeeding body annule; occasionally separation is not distinct and labial region appears to bear two annules.  

Stylet is 40 to 132 µm long.  

Vulva located on the 4th to the 21st annule from terminus, slit-like or completely closed by overhanging anterior lip.  

Tail is conoid-pointed to bluntly rounded. 

Males: Mostly unknown; have no stylet or caudal alae; have two to four lateral lines; bursa small, strongly reduced or lacking. 

Juveniles: Cuticle with scale-like cuticular appendages over entire body, usually with refractive elements or spine-like extensions at distal ends, arranged in 8 to 24 longitudinal rows.

[Ref: Raski & Luc, Rev. Nematol. 10(4):409-444 (1987), H. Ferris, Geraert (2010).] 

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

D-rated pest in California Nematode Pest Rating System.
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      Ring nematodes feed ectoparasitically on root tips or along more mature roots. The nematodes are migratory unless soil pore space limits their movement. 

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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 

These nematodes exhibit characteristic slow, sluggish movement.

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Extraction poor except with sugar/centrifuge.

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Andrassy, I. 1979. Revision of the subfamily Criconematinae Taylor 1936 (Nematoda). Opuscula Zoologica 16:11-57.

Clark, S.A. and A.R. Stone, 1976. Nematologica 21:256-266.

Cordero, M. A. Robert T. Robbins, Allen L. Szalanski. 2012. Taxonomic and Molecular Identification of Bakernema, Criconema, Hemicriconemoides, Ogma and Xenocriconemella Species (Nematoda: Criconematidae). J. Nematology 44: 427-446.

Geraert, E. 2010. The Criconematidae of the World: Identification of the Family Criconematidae. Academia Press, Gent. 615p.

Raski, D.J. and Luc, M. 1987. A reappraisal of Tylenchina (Nemata) 10. The superfamily Criconemaroidea Taylor, 1936. Rev. Nemarol. 10:409-444.

Copyright © 1999 by Howard Ferris.
Revised: July 28, 2020.