Reflections on the systematics of the Dorylaimoidea, a group of terrestrial and freshwater nematodes

The system of Dorylaimoidea is (some well-defined families excepted) unsatisfactory.It is difficult to establish groups on the basis of synapomorphies,the morphological characters being distributed erratically, many species were discovered and described in the 19th century when knowledge of the morphologywas almost nil (it remained in this state until 1936); moreover the importance of tail shape (very easy to observe) has been overrated strongly. Furthermore, the literature is full ofmisidentifications and should be consulted very critically.The author gives some suggestions that in future might lead to development of a better system.