Litylenchus crenatae




Rev 07/25/2022

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     Litylenchus crenatae Kanzaki, Ichihara, Aikawa, Ekino & Masuya, 2019

Designated subspecies: Litylenchus crenatae mccannii Carta et al., 2020

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Morphology and Anatomy:


  • Body cylindrical, vermiform, neither clearly obese or semi-obese
  • Cuticle striated, lateral field with typically six incisures, increasing to 6-8 incisures at midbody
  • Lip region weakly offset from bodycontour by a very shallow constriction
  • Stylet with narrow lumen, cone about one-third stylet length; shaft with prominent rounded basal knobs
  • DEGO just posterior to stylet knobs
  • Esophagus with cylindrical procorpus, weakly muscular metacorpus and large, broad and glandular postcorpus with short dorsal overlap of intestine
  • Excretory pore with clear secretory-excretory duct
  • Testis single, right subventral to ventral of intestine, outstretched, reaching to level, or beyond, esophageal glands with amoeboid sperm at posterior end
  • Distal end of vas deferens and rectum forming a cloacal tube around anterior part of spicule
  • Spicules typical of genus  separate with roundish capitulum and a smooth, curved horn-like blade
  • Gubernaculum present, simple crescent or bow-shaped
  • Bursa well developed, peloderan, arising before cloaca and terminating near tail tip
  • Tail conoid, bluntly pointed


  • Body cylindrical, vermiform to semi-obese, somewhat wider than male but not obese.
  • Monodelphic, prodelphic, ovary stretching to level of, or beyond, esophageal glands
  •  Gonad consisting of ovary, oviduct, spermatheca, crustaformeria, uterus, vulva/vagina and post-uterine sac from anterior to posterior; oocytes arranged in single row in entire ovary
  •  Spermatheca elongated oval- or roundish rectangle-shaped, not offset from gonad, filled with large sperm
  •  Crustaformeria consisting of four rows of four large and rounded cells, forming a quadricolumella
  •  Vagina perpendicular to body surface or slightly inclined anteriorly, with muscular constriction at uterus-vulva junction.
  • Vulva a horizontal slit, not protruding
  •  Post-uterine sac well developed,
  •  Rectum and anus present, functional; rectum < 1 abd, with muscular constriction at junction with intestine
  • Tail short, broad, distal end abruptly narrowing to a very short, conoid and bluntly pointed, tip.

.Ref: Kanzaki et al., 2019




 Reported median body size for this species (Length mm; width micrometers; weight micrograms) - Click:


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Litylenchus crenatae was described from the leaves of crenatae repens in Wellington, on the North Island of N

Extracted from leaf galls on leaves of Fagus crenata (beech) in Japan.  Similar galls were seen on Alnus (elm), Ostrya (hophornbeam) and other Fagus spp. but identity with this nematode species not yet confirmed (Kanzaki et al., 2019).

In USA, Beech Leaf Disease (BLD) was first discovered in Ohio in 2012 and has since spread to stands of American beech (Fagus grandifolia Ehrh.) across much of northern Ohio, western and northern Pennsylvania, New York, and Ontario, Canada (Ewing et al. 2018; Marra and LaMondia, 2020) .It has also been found on European beech (Fagus sylvatica L.) in Ohio.

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Economic Importance:

Beech trees are important shade and landscape trees. The wood is excellent as firewood.


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For an extensive host range list for this species, click

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Life Cycle:


Ecophysiological Parameters:

For Ecophysiological Parameters for this species, click If species level data are not available, click for genus level parameters

Mature males and females found in leaf galls from late spring to early summer.  The tree hosts are deciduous so the nematodes must be able to survive elswhere, possibly on the tree, until development of new leaves.  Life cycle details have not yet been elucidated.

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BLD symptoms are dark interveinal darkening of leaves appearing soon after spring flush. There is some puckering, crinkling and irregular thickening of leaves. Advanced stages of the disease lead to canopy thinning and sometimes to tree death. Beech seedlings inoculated with L. crenatae mccannii develop BLD symptoms (Carta et al. 2020; Marra and Lamondia, 2020).

Nematodes extracted leaves of American and European beech in North America are most similar to Litylenchus crenatae which is associated with leaf gall symptoms on Japanese beech (Fagus crenata) (Kanzaki et al. 2019). However, North American populations differ in morphology, host range, and ribosomal DNA markers from those in Japan, the North American nematodes associated with BLD have been designated subspecies L. crenatae mccannii (Carta et al. 2020).


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Host Plant Resistance, Non-hosts and Crop Rotation alternatives:

For plants reported to have some level of resistance to this species, click


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Carta, L.K., Handoo, Z.A., Li, S., Kantor, M., Bauchan, G., McCann, D., Gabriel, C.K., Yu, Q., Reed, S., Koch, J., Martin, D., Burke, D.J. 2020. Beech leaf disease symptoms caused by newly recognized nematode subspecies Litylenchus crenatae mccannii (Anguinata) described from Fagus grandifolia in North America. Forest Pathology 50:e12580.

Ewing, C. J.Hausman, C. E.Pogacnik, J.Slot, J., & Bonello, P. (2018). Beech leaf disease: An emerging forest epidemicForest Pathology, 49: e12488.

Kanzaki, N., Y. Ichihara, T. Aikawa, T. Ekino and H. Masuya. 2019. Litylenchus crenatae n. sp. (Tylenchomorpha: Anguinidae), a leaf gall nematode parasitising Fagus crenata Blume. Nematology 21:5-22.

Marra, R.F., LaMondia, J. 2020. First Report of Beech Leaf Disease, caused by the foliar nematode, Litylenchus crenatae mccannii, on American Beech (Fagus grandifolia) in Connecticut. Plant Disease 104:


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Copyright © 1999 by Howard Ferris.
Revised: July 25, 2022.