Morphological and molecular studies on Aphelenchoides arachidis Bos, 1977 (Tylenchina: Aphelenchoididae) from groundnuts in South Africa

Abstract

Aphelenchoides arachidisis reported for the first time from South Africa and for the fourth time outside Nigeria. TheA. arachidis-infested pods from South Africa showed the following symptoms: small seeds with the testa wrinkled and darker in colour than that of non-infested seeds; the pods showed dark lesions and some seeds within the pods showed early germination. Differences between the two South African and the Nigerian populations ofA. arachidisinclude more lateral lines in some specimens (2-4vs2) and, on average, longer post-uterine sac length (extending for 74 (41-96) and 62 (33-82)vsabout 50% of vulva to anus distance). Scanning electron micrographs of this species are presented for the first time. The ITS regions of ribosomal DNA were amplified, sequenced, aligned and compared with other sequences ofAphelenchoidesspecies. Two pathogenic fungi,Thielaviopsis basicolaandNeocosmospora vasinfecta, were also isolated from this material.