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Burrowing Nematode

Scientific Name
Radopholus similis
Scientific Author
(Cobb, 1893) Thorne, 1949
Taxonomy
(Nematoda: Tylenchida: Pratylenchidae)
Pest Status
0 Unknown
Status
NZ - Exotic
Reliability
High
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Diagnostic Images

Pharyngeal Region - Female
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Caption
Slide mounted
Source
Zeng Zhao Landcare Research
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Diagnostic Images (6)
Other Images (8)
Diagnostic Notes
As a plant-parasitic nematode belonging to the order Tylenchida, R. similis has the following characteristics of that order: annulated cuticle; small, pocket-like amphids opening on the lip region; hollow, axial stylet in the stoma which can be protruded for feeding, excretory system with a single lateral canal; oesophagus divided into anterior procorpus, median bulb with valve plates, isthmus surrounded by nerve ring and a glandular basal portion; dorsal oesophageal gland open into the lumen of the oesophagus just behind the base of the stylet.

R. similis are small nematodes (less than 1 mm long) with elongate tail and marked sexual dimorphism in the anterior region. Female: Head hemispherical, rarely slightly set off. 3-6 lip annules. Stylet well defined with rounded knobs. 4 lateral incisures. Vulva post-equatorial, sometimes with slight protuberant lips. 2 functional and equally developed ovaries, each bearing a spheroid spermatheca often with small rod-shaped sperm. Metacorpus well developed, elongate to ellipsoidal with distinct valves. 3 glandular cells lie on the dorsal side of the body. Tail elongate-conoid with narrowly rounded terminus. Male: The knob-shaped head is set off by a definitive constriction. Compared to females lateral lips are distinctly smaller. Head annules not observed. Cephalic sclerotisation, stylet, median bulb and pharyngeal gland lobe weakly developed. 4 lateral incisures present. Inner incisures faint. Caudal alae pronounced, arising about one body width anterior to the spicule head and extending to about 1-2 body widths anterior to the tail tip. Gubernaculum with small titillae. Spicules dorsally arched.

CABI CPC 2006. Measurements (Topotypes, after Sher, 1968)

12 females: L = 520-880 (690) µm; a = 22-30 (27); b = 4.7-7.4 (6.5); b' = 3.5-5.2 (4.5); c = 8-13 (10.6); c' = 2.9-4.0 (3.4); V = 55-61 (56); spear = 17-20 (19) µm; o = 12-20 (18). 5 males: L = 590-670 (630) µm; a = 31-44 (35); b = 6.1-6.6 (6.4); b' = 4.1-4.9 (4.8); c = 8-10 (9); c' = 5.1-6.7 (5.7); spear = 12-17 (14) µm; spicules = 19-22 (20) µm; gubernaculum = 8-12 (9) µm.

Topotypes, after Taylor, 1969

20 females (young): L = 540-660 (605.2) µm; V = 53-58 (55.9); tail length = 55-77 (66.9) µm; spear = 18 µm; phasmids from tail terminus = 44-61 (53) µm. 6 females (gravid): L = 610-745 (685.8) µm; V = 52-57 (55.3); tail length = 52-74 (59.8) µm; spear = 18 µm; eggs = 50-68 (56.1) µm x 19-30 (23.3) µm. 12 males: L = 535-650 (585) µm; tail length = 64-86 (72.8) µm; spear = 12 µm; spicules = 18-19 (18.2) µm; gubernaculum = 10-11 (10.3) µm; phasmids from tail terminus = 46-58 (53.7) µm.

References

- Diagnostic characters: (Dr Zeng Qi Zhao, Landcare Research, Auckland, New Zealand).
More Information
Specimen Contact
MAF Plant Health & Environment Laboratory (Nematode collection held by Zeng Zhao at Landcare Research)
Author
Zhao, Z. Q. & Crosby, T. K.
Created
26/05/2011 07:34 AEST
Last Updated
07/07/2011 07:09 AEST
Citation
Zhao, Z. Q. & Crosby, T. K. (2011) Burrowing Nematode (Radopholus similis) Updated on 7/7/2011 7:09:28 AM Available online: PaDIL - http://www.padil.gov.au.
Image Use
Free for use under the Creative Commons Attribution 3.0 Australia License

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