The Structure of the Anterior Feeding Apparatus in Members of the Ironidae (Nematoda : Enoplida)

Abstract

The structure of the adult anterior feeding apparatus of Ironus, Thalassironus, Trissonchulus and Dolicholaimus is described, including hitherto unrecorded structures such as stomodeal pouches, protractors, retractors and tooth muscles. The existence of hydrostatic tissue is assumed. The feeding method of Ironidae was studied and the action of muscles associated with feeding was analysed. The unusual arrangement of the lips and position of the ventral gland orifice in the labial region of Ironidae is discussed, and the suggestion made that the ventral gland produces enzymes that may aid extra-corporal digestion. In attempting to homologize the different structures of the anterior feeding apparatus in the different genera, a general scheme for the Ironidae is drawn up, based on the supposed ancestral triradial symmetry of the teeth and stomodeal muscles. The taxonomy of Trissonchulus and Dolicholaimus is discussed.