Morphological and karyotypic differences within and among populations of Radopholus similis

Abstract

Twenty populations of Radopholus similis from three countries and diferent hosts (19 populations from ornamental plants and one population from ginger) were compared using morphological characters, mor-phometrics and karyotype between progeny from both single females and 30 females of each population. Morphological diversity existed in and among the populations, even within the progeny nematodes from single nematodes compared to that of 30 females. Te labial disc shape, the number of head annuli, the terminated position of lateral lips, the number of genital papillae before cloacal apertures and female and male tail terminal shape showed variation. In addition, genital papillae arranged in a double row before cloacal apertures was frst found in two ornamental populations. Te karyotype of all the 20 populations was n = 5. Combining our results and previous studies, we support that R. citrophilus is a synonym of R. similis, and that it is not possible to distinguish physiological races or pathotypes of R. similis according to morphological characters or karyotype.