A new system for Nematoda: combining morphological characters with molecular trees, and translating clades into ranks and taxa

Summary Very recently, we proposed a new classification for the phylum Nematoda, based primarily on phylogenetic hypotheses resulting from small subunit ribosomal DNA (SSU rDNA) sequence analysis. The strength and weaknesses of this new system are discussed with particular regard to ranks and names of clades. As almost 2 years have passed since we finished writing the original manuscript, we also provide a timely update on the implications of subsequent phylogenetic analyses, with appropriate improvements and corrections to our system. We emphasise the importance of disentangling the deep branches of the nematode tree, and discuss various scenarios with some tantalising implications for understanding of morphology and ecology of the earliest nematodes.