Rev 05/13/2022

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           Hemicriconemoides Chitwood & Birchfield, 1957

Type species of the genus: Hemicriconemoides wessoni Chitwood & Birchfield, 1957



As of October 2003, the Zoological Record indicated 54 species names associated with this genus. More recent data indicate 52 valid species (Van den Berg et al., 2014)

Key to some species of Hemicriconemoides

(adapted from Dasgupta, Raski and Van Gundy, 1969)

1. Lip region strongly offset H. obtusus
Lip region slightly offset or not offset 2
2 Stylet knobs rounded without forward processes H. strictathecatus
Stylet knobs anchor shaped with prominent forward processes 3
3 Vulva on 2nd annule from tail tip, fewer than 56 annules in sheath, sheath annules rounded H. brevicaudatus
Vulva on 7th to 21st annule from tail tip, more than 75 annules in sheath, sheath annules flattened 4
4 Stylet < 46 µm H. microdoratus
Stylet > 46 µm 5
5 Vulval sheath present 6
Vulval sheath absent 10
6 Fewer than 98 annules in sheath 7
More than 98 annules in sheath 9
7 Stylet > 71 µm H. minutus
Stylet < 60 µm 8
8 Tail narrows abruptly after anus H. wessoni
Tail regularly conoid after anus H. intermedius
9 Lip region rounded, no amphidial plate, tail rounded H. brachyurus
Lip region truncate, no amphidial plate, tail tapered H. cocophilus
10 Lip region conoid, vulva on 16th to 21st annule from tail tip H. kanayaensis
Lip region rounded to truncate, vulva on 7th to 17th annule from tail tip 11
11 Lip region with a conspicuously large annule H. insignis
Lip region with 2 distinct annules 12
12 Length = 0.29-0.38 mm H. parvus
Length = 0.41-0.61 mm 13
13 Fewer than 104 annules in sheath, stylet < 60 µm H. pseudobrachyurum
More than 104 annules in sheath, stylet > 60 µm 14
14 Tail rounded or convex to conoid H. mangiferae
Tail conoid, tapering to an angular tip 15
15 Lip region rounded, not offset, first annule rounded, second annule as large or larger than first H. gaddi
Lip region truncate, slightly offset, first annule angular, second annule smaller than first H. chitwoodi

 The genus Hemicriconemoides was created to include those species that did not fit well into the genera Criconemoides Taylor, 1936 or Hemicycliophora de Man, 1921.

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Morphology and Anatomy:

The common name "Sheathoid Nematode" for Hemicriconemoides spp. is based on the loose, smooth outer cuticular sheath in adult females.  The sheath is attached to the nematode boy at the head and vulva.  Males and juveniles have only a single cuticle layer which, in juveniles, is ornamented with rows of scales and spines. Sexual dimorphism isd strong with males appearing smaller than females and having reduced feeding and genital structures.


Photographs from Inserra et al., 2014)
Male:  Slender.
  • Esophagus degenerated.
  • Stylet absent.  
  • Spicules slender, slightly curved.
  • Gubernaculum short and plain.  
  • Caudal alae rarely present, if so, weakly developed.  
  • Penial tube rarely present, if so, short.


  • One-layered cuticle.
  • Submedian lobes of lip annules sometimes present, weakly developed.
  • Strong annulation; each annule with six, ten, or twelve scales which are either conoid or provided with short denticles.  When six scales six on an annule, alternate with the following annule (twelve rows).

[Ref: Raski and Luc (1987); Van den Berg et al.. (2014).]

Female:  Small to medium size (0.29 to 0.67 mm).  
  • Body plump, straight or slightly ventrally curved, tapering on short distance at both ends.  
  • Number of annules 51-164.  
  • Cuticle with two detached layers, closely adpressed; annulation strong, not retrorse.
  • Lateral field not marked. 
  • Vulva posterior.  Vulval lips plain; vulval flaps occasionally present. 
  • Tail short, conoid to rounded.  
  • Labial framework heavily sclerotized.  First anterior annules only weakly differentiated.  No submedian lobes.
  • Amphid apertures slit-like.  
  • Stylet strong; basal knobs directed forward, generally with a jointed anterior process; rarely rounded; never sloping backwards. 
Body size range for the species of this genus in the database - Click:


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The type species is Hemicriconemoides wessoni Chitwood and Birchfield, 1957 Goodey, 1963, originally collected from Florida on Myrica cerifera (southern wax myrtle) (Dasgupta et al., 1969).

Warm temperatures, flooding, and overwatering favor an increase of sheathoid nematode population levels (Inserra et al., 2014)

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Economic Importance:

C-rated pest in California Nematode Pest Rating SystemHemicriconemoides wessoni causes damage to turf grasses in Florida.

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Feed as migratory ectoparasites, usually near root tip.  Females of H. strictathecatus in Florida are reported to have semiendoparasitic habits; they are found partially embedded with the anterior portion of their body inside the root to feed on cortical cell tissue near the root tip. These females remained attached to the root even after the removal of the soil particles that coated the root (Inserra et al., 2014).

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Cucurbitaceae, Leguminosae, Rutaceae, Solanaceae, and Umbelliferae. Species of the genus are frequently reported from roots of trees and grasses.
For an extensive host range list for this genus, click
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Life Cycle:

Eggs, four juvenile stages and adults. Juveniles have a single cuticle, ornamented by rows of scales and spines.

For Ecophysiological Parameters for this genus, click 
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Many species of Hemicriconemoides are present in  mixed hardwood forests and natural areas, but their economic importance in agriculture is largely undetermined. They have been found on golf courses showing nematode feeding damage, but in these cases, there were many co-occurring nematode species, so it was not possible to determine which species were responsible for damage (Zhang et al., 2012).

Generally, although sheathoid nematode species cause decline of some crops, most species are not considered aggressive parasites.

In Florida and in other countries, damage is documented for litchi, mango (H. mangiferae), sugarcane, and tea (Inserra et al., 2014).

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Chitambar, J. J., Westerdahl, B. B., and Subbotin, S. A. 2018. Plant Parasitic Nematodes in California Agriculture. In Subbotin, S., Chitambar J., (eds) Plant Parasitic Nematodes in Sustainable Agriculture of North America. Sustainability in Plant and Crop Protection. Springer, Cham.

Dasgupta, D. R., Raski, D. J and Van Gundy, S. D. 1969. Revision of the genus Hemicriconemoides Chitwood & Birchfield, 1957 (Nematoda: Criconematidae). J. Nematol. 1: 126-145.

Geraert, E. 2010. The Criconematidae of the World. Identification of the Family Criconematidae (Nematoda). Ghent, Academia Press. 615p.

 Inserra, R.N., Stanley, J.D., Ochoa, A., Schubert, T.S., Subbotin, S.A., Crow, W.T., McSorley, R. 2014. Hemicriconemoides Species as Crop Damaging Parasitic Nematodes in Florida. Nematology Circular No. 223 Florida Department of Agriculture and Consumer Services., Division of Plant Industry.

McSorley, R., Campbell, C.W. and Goldweber, S. 1980. Observations on a mango decline in south Florida. Proceedings of Florida State Horticultural Society 93, 132-133.

Raski, D.J. and Luc,, M. 1987.  Rev. Nematol. 10:409-444 (1987).

Scheck, H.J. 2021. California Pest Rating Proposal for Hemicriconemoides spp. (Chitwood & Birchfield, 1957) Sheathoid nematodes  CDFA, Sacramento.

 Van den Berg, E., Tiedt, L.R., Inserra, R.N., Stanley, J.D., Vovlas, N., Palomares Rius, J.E., Castillo, P., Subbotin, S.A. 2014. Morphological and molecular charcterisation of some Hemicriconemaodes species (Nematoda: Criconematidae) together with a phylogeny of the genus. Nematology 16:519-553.

Whitlock, L.S. and A.E. Steele. 1960. Notes on Hemicriconemoides gaddi from camellias in Louisiana and Georgia. Plant Disease Reporter 44: 446-447.

Zeng, Y., Ye, W., Tredway, L., Martin, S. and Martin, M., 2012. Taxonomy and morphology of plant-parasitic nematodes associated with turfgrasses in North and South Carolina, USA. Zootaxa, 3452(1), pp.1-46. Dasgupta, D.R., D.J. Raski and S.D. Van Gundy 1969. Revision of the genus Hemicriconemoides Chitwood and Birchfield, 1957 ( Nematoda: Criconematidae). J. Nematology 1:126-145.


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Copyright © 1999 by Howard Ferris.
Revised: May 13, 2022.