Morphology of larval Gordius dimorphus (Nematomorpha: Gordiida).

Scanning electron microscopy was used to analyze superficial features of Gordius dimorphus Poinar, 1991, larvae that might serve as generic or specific diagnostic characters. Three adults of G. dimorphus (2 males and 1 female) were maintained under laboratory conditions until oviposition, which occurred within long strings commonly referred to as egg strings. Larvae have a cylindrical body, annulated and divided into 2 sections, plus an anterior preseptum and a posterior postseptum. Three concentric rings with 6 spines each surround the proboscis. The proboscis is retractile, dorsoventrally flattened, with 1 pair of forceps-like projections on its distal-most portion. On the surface of each projection, 3 pairs of aculeiforms spines are aligned and lean toward the proboscis opening. One large spine is present on the posterior portion of the postseptum. Papillae were not observed. Gordius dimorphus larvae are similar to previous light microscope descriptions. This is the first record of G. dimorphus in Brazil.