Morphometric Evaluation of Hypotriploid and Triploid Populations of Meloidogyne arenaria

A morphometric comparison of seven hypotriploid populations with five pooled triploid populations of Meloidogyne arenaria was made using standard descriptive statistics, stepwise discriminant analysis (SDA), and cluster analysis. Six morphometric characters of females, 14 of second-stage juveniles (J2), and 18 of males were measured for each population. Useful differentiating characters included: body length in J2; stylet length in females and J2; stylet-knob dimensions in females and males; dorsal esophageal gland orifice distance in all three life stages; esophagus-length ratio in males and J2; excretory pore position in J2; and spicule length in males. SDA and cluster analysis showed that in each life stage, the hypotriploid populations were set off to varying degrees from the triploid populations. In addition, the relationships among populations differed when different life stages were compared. No consistent relationships could be detected among the populations, when morphometric data of the present study and morphological findings of the same populations in a parallel study were considered. Morphometric differences were not sufficient to propose any of the hypotriploid populations as new species.