Description of Globodera capensis n. sp. (Nematoda: Heteroderidae) from South Africa

Abstract

A new cyst nematode, herein described as Globodera capensis n. sp., was found on several farms in the Swartland and Sandveld areas in South Africa. As the host plant of G. capensis n. sp. is currently unknown, the species is represented by cysts and second-stage juveniles (J2) only. The cysts have a spherical form, are yellow to dark brown in colour and have bullae (vulval bodies) and subcuticular punctations. Six to 20 cuticular ridges/lines are present between the anus and vulval basin, Granek’s ratio is 0.7-4.0, the vulval basin diam. is 16-28.5 μm and vulval basin to anus distance is 19-60 μm. The J2 is 430-528 μm long and the stylet is 23-28 μm long with anteriorly flattened to rounded stylet knobs. These stages are morphologically and morphometrically very near to, or indistinguishable from PCN, G. artemisiae, G. millefolii and G. tabacum tabacum. It can be distinguished by the molecular characteristics of the ITS-region of the ribosomal DNA. Pairwise distances between closely related Globodera species show that G. capensis n. sp. differs the least in number of base differences per sequence from G. millefolii (63-64 bp) and most from an undescribed Globodera from Chile (72-73 bp). Phylogenetic relationships of G. capensis n. sp. with selected species of Punctoderinae, inferred from ITS-rRNA sequences by using the Maximum Likelihood method, indicate that G. capensis n. sp. occupies a basal position within a lineage of Globodera species from Europe, Asia and New Zealand that parasitises non-solanaceous plants. For diagnostic purposes, digestion of the ITS1 with AluI will distinguish G. capensis n. sp. from G. mexicana, G. pallida, G. rostochiensis and G. tabacum, but not from G. artemisiae, G. millefolii and G. zelandica, whilst FauI will distinguish G. capensis n. sp. from all the other Globodera species tested.