Morphometric analysis of nonadult characters of common species of American gordiids (Nematomorpha: Gordioidea).

ABSTRACT

The nonadult stages, egg strings, eggs, larvae, and cysts of Gordius robustus, Paragordius varius, and Chordodes morgani are described morphometrically. The goal was to document the differences between species and to evaluate the usefulness of morphometrics in species identification. In concert, multivariate analysis of variance (MANOVA) and univariate analysis of variance (ANOVA, a posteriori contrasts) statistical tests demonstrated that each species is morphometrically distinguishable from all others. Additionally, discriminant function analysis indicated that postseptum length, pseudointestine length, and stylet width were the most important variables in the discrimination of species based on larval characters. Finally, differences in oviposition behaviors among these 3 species were found. It is suggested that ovipositioning differences may place larvae into distinct niches and may ultimately lead to the use of different paratenic hosts by different gordiid species.