THE GLANDULAR SENSORY ORGAN OF DESMODORIDAE (NEMATODA)-ULTRASTRUCTURE AND PHYLOGENETIC IMPLICATIONS

The glandular sensory organ found in representatives of all genera of Stilbonematinae (Nematoda, Desmodoridae) so far described was investigated by means of scanning and transmission electron microscopy. It is composed of one type A and one type B glandular cell, one monociliated sensory cell, and a hollow seta. Whereas the Stilbonematinae have ectosymbiotic bacteria coating the cuticle, for an outgroup comparison three non-symbiotic species belonging to three genera from the closely related subfamilies Desmodorinae and Spiriniinae were chosen. In these three species the glandular sensory organ is composed of one type A glandular cell, one biciliated sensory cell, and a hollow seta. The consistent structure of a highly complex organ such as the glandular sensory organ with one type B glandular cell and one monociliated sensory cell suggests that the Stilbonematinae are monophyletic in spite of their otherwise diverse morphology.