Inter-population variability of Longidorus euonymus Mali and Hooper, 1974 (Nematoda, Dorylaimida) and comment upon the number of juvenile developmental stages

Longidorus euonymus is distributed widely in central and southern Europe. Nematodes typically have four pre-adult stages, however, there has been confusion in the scientific literature with regard to the number of juvenile developmental stages (JDS) of L. euonymus with three and four JDS being reported. A principal component analysis of published morphometric data from 33 L. euonymus populations unequivocally showed that there were four juvenile developmental stages. Furthermore, 18S rDNA sequence analysis indicated that L. euonymus was more closely related to L. elongatus and L. attenuatus than to L. vineacola. This was in discordance with the original description of the species; however, the maximum likelihood distances between the species were relatively small.