Description of Globodera ellingtonae n. sp. (Nematoda: Heteroderidae) from Oregon

Zafar A. Handoo, Lynn K. Carta, Andrea M. Skantar, David J. Chitwood

Abstract


A new species of cyst nematode, Globodera ellingtonae, is described from soil collected from a field in Oregon. Second-stage juveniles (J2) of the species are characterized by body length of 365-515 mm, stylet length of 19-22.5 mm, basal knobs rounded posteriorly and pointed anteriorly, tail 39-55 mm, hyaline tail terminus 20-32.5 mm, and tail tapering uniformly but abruptly narrowing and constricted near the posterior third of the hyaline portion, ending with a peg-like, finely rounded to pointed terminus. Cysts are spherical to sub-spherical, dark to light brown and circumfenestrate and cyst wall pattern is ridge-like with heavy punctations. Males have a stylet length of 21-25 mmand spicule length of 30-37 mmwith a pointed thorn-like tip. Females have a stylet length of 20-22.5 mm, one head annule and labial disc, heavy punctations on the cuticle, and short vulval slit 7.5-8 mm long. Morphologically this new, round-cyst species differs from the related species G. pallida, G. rostochiensis, G. tabacum complex and G. mexicana by its distinctive J2 tail, and by one or another of the following: shorter mean stylet length in J2, females and males; number of refractive bodies in the hyaline tail terminus of J2; cyst morphology including Granek’s ratio; number of cuticular ridges between the anus and vulva; and in the shape and length of spicules in males. Its relationship to these closely related species are discussed. Based upon analysis of ribosomal internal transcribed spacer (ITS) sequences, G. ellingtonae n. sp. is distinct from G. pallida, G. rostochiensis, G. tabacum and G. mexicana. Bayesian and Maximum Parsimony analysis of cloned ITS rRNA gene sequences indicated three clades, with intraspecific variability as high as 2.8%. In silico analysis revealed ITS restriction fragment length polymorphisms for enzymes Bsh 1236I, Hinf I, and Rsa I that overlap patterns for other Globodera species.

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