Family Leptonchidae

Revised 03/14/23

Leptonchidae Thorne, 1935         

synonyms:   

Belonenchidae Thorne, 1964

Basirotyleptidae Siddiqi and Khan, 1964

Tylencholaimellidae, Jairajpuri, 1964

Encholaimidae Golden and Murphy, 1967

Tyleptidae Monteiro, 1970
   

There are two cuticle types in the Dorylaimida: (a) dorylaimoid with the inner layer not loose or separated from the outer layes and without radial cuticular elements; (b) tylencholaimoid in which the  inner cuticular layer is loose and there are irregular radial elements. Among all the families of the Dorylaimida, only Leptonchidae and Tylencholaimidae have the tylencholaimoid cuticle; other families have a dorylaimoid cuticle (Wu et al., 2019).

Males with two testes and two adanal papillae.

• Small to medium size, up to 3 mm long.
• Cuticle typical tylencholaimoid, with loose inner cuticle layer and abundant radial refractive elements.
• Excretory pores in two lateral rows on each side on cuticle.
• Lip region cap-like, usually offset by constrictionc.
• Cheilostom a truncate cone.
• Odontostyle highly variable, usually thin and needle-like, almost always shorter than lip region width.
• Odontophore rod-like, with or without basal flanges.
• Anterior region of esophagus slender and weakly muscular; esophagus expansion a basal bulb, often pyriform, occupying 1/4 to 1.3 of total esophaguus length; sometimes with a valved chamber.
• Female genital system didelphic or monodelphic.
• Vulva transverse, rarely longitudinal or pore-like.
• Male with dorylaimid spicules and few evenly-spaced ventromedian supplements.
• Tail similar in noth sexes: short and rounded, occasionally conical or long and filiform.

Ref: Pena-Santiago, 2006.

Characteristics of some Genera:

Leptonchus  spear very slender, spear extension arced and strongly cuticularized.  Diovarial, amphidelphic.

Proleptonchus:  spear curved, spear extension not strongly cuticular. Monovarial, prodelphic.

Dorylaimoides spear asymmetrical, spear extension angular.  Diovarial, amphidelphic. (moved to family Mydonomidae)

Doryllium:  Very short spear, spear extension with flanges or flattened knobs.  Monovarial, opisthodelphic. (Moved to family Tylencholaimellidae)

Tylencholaimellus  Spear with dorsal thickened portion; spear extension knobbed at base.  Monovarial, opisthodelphic. (Moved to family Tylencholaimellidae)

Funaria: very small spear; stoma wall cuticularized, stoma an inverse cone. Diovarial, amphidelphic.

Apoleptonchus very slender spear, narrow lumen, small aperture; spear extension with or without flanges. Didelphic or monodelphic.

Proleptonchoidesvery slender spear, narrow lumen, small aperture; spear extension with flanges. Monodelphic prodelphic..

Paraleptonchusvery slender spear, narrow lumen, small aperture; spear extension arched; esophagus anterior convoluteed.  Monovarial prodelphic.

Meylis Spear slender, extension simple, no flanges. Diovarial amphidelphic.

Bertzuckermania Spear slender, extension simple, no flanges. Diovarial amphidelphic..

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References

Andrassy, I. 2009. Free-living Nematodes of Hungary (Nematoda Errantia) Vol. 111. Humgarian Natural History Museum, Budapest. 508p.

Bongers, De Nematoden Van Nederland

Goodey, Soil and Freshwater Nematodes

Goseco,C.G., Ferris, V.R. and Ferris, J.M. 1974. Revisions in Leptonchoidea (Nematoda: Dorylaimida). Leptonchus, Proleptonchus, Funaria, and Meylis n.gen. in Leptonchidae, Leptonchinae. Research Bull. Ag. Exp. Sta, Purdue Univ. 911. 32p.

Pena-Santiago, R. 2006. Dorylaimida Part 1. Superfamilies Belondiroidea, Nygolaimoidea and Tylencholaimoidea. Pp 326-391 in  E. Abebe, István Andrássy, W. Traunspurger (eds) Freshwater Nematodes: Ecology and Taxonomy. CABI Publishing.

Wu, W-J., Xu, C-L., Xie, H., Wang, D-W. 2019. Three new species, one new genus and subfamily of Dorylaimida (de man, 1876) Pearse, 1942, and revisions of the families Tylencholaimellidae Jairajpuri, 1964 and Mydonomidae Thorne, 1964 (Nematoda, Dorylaimida). PeerJ 7:e7541 https://doi.org/10.7717/peerj.7541

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