Superfamily CRICONEMATOIDEA

                                           Rev 09/26/07

Classification:

      Tylenchida
       Tylenchina
        Criconematoidea (Taylor, 1936)
    Synonyms:
      Criconematina (Siddiqi, 1980)
      Hemicycliophoroidea (Skarbilovich, 1959)
      Tylenchocriconematoidea (Raski & Siddiqui, 1975)

Classification and Characteristics Chart of the Order Tylenchida

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Morphology and Anatomy:

All stages:

• Usually under 1 mm long, but longer in a few cases (up to 1.9 mm in Hemicycliophorinae). 
• Marked sexual dimorphism; male slender, female sausage-shaped, cylindrical or spheroidal. 

Female:

• Female and juvenile with extremely variable cuticle; thick with retrorse annuli, lacking lateral field, may have lobes, crenation, spines, scales; or thick with smooth, coarse, rounded annuli covered or not with an extra-cuticular layer; or thin cuticle with fine rounded annuli and lateral fields often marked with lines (obliterated in swollen stages). 
• Labial area in female and juvenile with usually one or two often modified annuli; oral aperture dorso-ventrally longitudinal on a raised area or labial disc. 
• Basically, there are six pseudolips of which the four submedian ones can bear each a submedian lobe; no sensillae visible on surface of lip area.  Labial framework hexaradiate, with light to strong sclerotization. 
• Amphid openings round to oval, close to labial disc area. 
• Deirids reported in thin-cuticled genera Tylenchulus and Paratylenchus. 
• Phasmids absent. 
• Females and most juveniles with well-developed stylet, often very long, with cone markedly longer than the shaft; basal knobs well-developed, either sloping backwards or anchor-shaped. 
• Female and juvenile esophagus with median bulb enormously developed, muscular, containing a large, often elongated cuticular valvular apparatus and being amalgamated with procorpus, which is usually broad and surrounds the basal region of the stylet;
• Isthmus either slender and offset from glandular bulb or short, broad and amalgamated with glandular bulb. 
• Esophageal glandular bulb small, offset from intestine (except in Sphaeronema whittoni and Meloidoderita kirjanovae in which the glands are free). 
• Orifice or dorsal esophageal gland at a short distance (usually under 4 µm) behind stylet base. 
• Vulva transversely oval or slit-like, located posteriorly, usually at over 75% of body length. 
• Female genital tract has one branch, anterior, outstretched (may be coiled in swollen females). 
• Post-vulval uterine sac absent. In juveniles, female genital primordium shows no element of a posterior branch. 
• Spermatheca usually offset and inclined laterally or ventrally. 
• Uterus with a distinct columned part, but number of rows of cells apparently not constant; in swollen females vagina can have a thickened wall, transformed into a cyst in Meloidoderita. 
• Swollen female may deposit numerous eggs in a gelatinous matrix produced by the excretory system. 
• Intestine syncytial, lacking a definite lumen, often extending beyond anus.
• Female anus a small pore, absent in rare cases.

Male:

• Small, slender. 
• Cuticle thin, with narrow annuli; no extra-cuticular layer; typical lateral field present.
• Stylet mostly absent or degenerated and non-functional. 
• Esophagus degenerated, nonfunctional. 
• One testis. 
• Spicules often very long and setaceous, with small narrow head, elongate-slender shaft and finely pointed distal end; variable in shape, but often arcuate.
• Gubernaculum linear or crescent-shaped in lateral view, not protrusible.
• Caudal alae, when present, usually low, rarely peloderan; but well-developed, leptoderan in Tylenchocriconematinae and most Hemicycliophorinae. 
• cloacal lips usually narrow and elevated, or drawn out as a penial tube. 
• Hypotygma may be present or absent.

References:
Raski & Luc, Rev. Nematol. 10(4):409-444 (1987)

H. Ferris.

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