© 2001 Kluwer Academic Publishers. Printed in the Netherlands. 1 Phylogeny of decapods: moving towards a consensus

Although the recognition of four broad groups within Decapoda – natantians, macrurans, anomurans and brachy-urans – has long been a staple of textbooks and even the primary taxonomic literature, a precise resolution of phylogenetic relationships within the order has proved more difficult. Indeed, there have been as many schemes of decapod taxonomy and phylogeny as there were experts who wished to offer an opinion. In this decade, utilization of explicit cladistic methods of analysis and the application of molecular techniques have produced a series of clear hypotheses concerning the relationships within many of the groups of Decapoda. It is apparent that earlier conflicts of opinion can be related in part to the implicit problems of dealing with paraphyletic groups near the base of the tree that are too broadly defined by only general or plesiomorphic features. Comprehensive morphological analyses of both fossil and living forms, with attention being paid to defining synapomorphies, can lead to resolution of old controversies. Molecular techniques hold great promise towards providing further resolution, but currently suffer from insufficiencies of sampling. Nevertheless, where once there was chaos and vexation, there is now some enlightenment. The situation can only improve, but the broad outlines of decapod deep history are already emerging