Neogastropoda are generally considered to be monophyletic, although their monophyly is usually challenged in molecular phylogenies. Such results suggest that serious reconsideration of the synapomorphies and autapomorphies defining the group is needed. One of the uncontroversial monophyletic groupings within the neogastropods is the superfamily Buccinoidea. This taxonomically rich clade lacks two out of three characters that are considered to be key autapomorphies of Neogastropoda, namely accessory salivary glands and the rectal gland. The only other autapomorphy that unites Buccinoidea with the rest of Neogastropoda is the valve of Leiblein. This study of the mor- phology of the valve of Leiblein of different neogastropods (two species of Raphitominae, Conidae, one of Muricidae, one of Nassariidae, one of Buccinidae, one of Cancellariidae, and one of Olividae) revealed its strong morphological hetero- geneity. Published and original data on the embryonic devel- opment of the valve in Buccinidae and Muricidae demonstrate that the valve originates from different sections of the anterior foregut. Preliminary data indicate that the homology of the valve of Leiblein within Neogastropoda is, at best, question- able. This casts further doubts on the monophyly of the Neo- gastropoda, which probably include at least two stems.
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