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.

A new orthopteran-parasitizing horsehair worm, Acutogordius taiwanensis sp. n., with a redescription of Chordodes formosanus and novel host records from Taiwan (Nematomorpha, Gordiida)

“…Larval worms are thought to stay on the river bottom and be passively ingested by paratenic hosts (Hanelt et al 2005). Folding their bodies may provide a benefit by reducing the water flow or by making them easy to ingest because the postseptum in Acutogordius , as well as in Gordius , is significantly longer than in other genera (Hanelt and Janovy 2002, Szmygiel et al 2014). …”

“…The terminology for larval stages used in this study primarily followed that of Hanelt and Janovy (2002) and Szmygiel et al (2014).…”

A new horsehair worm, Chordodes formosanus sp. n. (Nematomorpha, Gordiida) from Hierodula mantids of Taiwan and Japan with redescription of a closely related species, Chordodes japonensis

“…The terminology of larvae follows that of Bohall et al (1997), Hanelt and Janovy (2002), and Bolek et al (2010).…”

Going Solo: Discovery of the First Parthenogenetic Gordiid (Nematomorpha: Gordiida)

“…2B). Females did not attempt to attach egg strings to aerators, air hoses, or 1 liter bottles but instead deposited egg strings free in the water column, as previously described for P. varius [20]. Undeveloped eggs were 41.6 (36.5–48.7) µm by 26.9 (23.4.0–30.2) µm.…”

“…At least 30 measurements were taken of each character, following a previously described protocol [20]. Adults were examined by scanning electron microscopy (SEM) by removing a 5–10 mm section of the mid-body cuticle and the entire posterior end.…”