Scanning electron microscopy of the cephalic structures of Pneumospiruridae. (Thelazioidea - Nematoda). Revision of the family.

In a study with the scanning electron microscope (SEM) five different types of cephalic structure were found in five species of Pneumospiruridae recorded in Israel. The description, in the literature, of a sixth type, based on a study with the light microscope, was also considered in evaluating the results. By comparing descriptions and drawings of the known Pneumospiruridae with the SEM micrographs the species in the family were grouped into two genera: 1. Vogeloides Dougherty, 1952 in which the form of the cephalic structures could be correlated with the structure of the oesophagus; 2. Metathelazia Skinker, 1931 in which the cephalic structures could not be correlated with any other morphological or anatomical character. The species included in the genus Metathelazia were therefore grouped on the basis of the form of cephalic structures in 5 types: booliati, multipapillata, acomysi, capsulata and rodentium. The genus Pneumospirura Wu and Hu, 1938 is considered a subjective synonym of Metathelazia.