The Anomura is not shown to be a monophyletic assemblage (Fig.1, point B). One excluded taxon is Lomis hirta (Lomidae), which is depicted in a very basal position, reflecting a plesiomorphic spermatozoal morphology (Tudge 1996b). Also, the questionable placement of the thalassinid, Thalassina squamifera, with the hippoid, Hippa pacifica, within the ‘anomuran‘ clade makes the Anomura paraphyletic. For both Lomis and Thalassina the spermatozoal and spermatophore morphology is not fully known or is contentious (Tudge, 1995a, b), and further study may alter these relationships.
The clade containing the vast majority of the anomuran taxa (Fig. 1, point B) is primarily characterized by the unambiguous character state change from spermatozoal microtubular arms of nuclear origin to such arms being cytoplasmic in origin (see character 1, Appendix A). This character is equivocal in Lomis and Thalassina (see Data matrix, Appendix B) and may go some way towards explaining their contentious placement (Fig. 1 & Fig. 2).