Fig. 2

Summary of the Hox and ParaHox genes identified in the eight molluscan species studied herein. For comparison, the putative ancestral lophotrochozoan gene toolkit is provided. Tree topology follows Smith et al. [61]. The colored boxes indicate the anterior, central, and posterior Hox as well as the ParaHox paralog groups. To date, no known Hox or ParaHox sequences (represented by question marks) belonging to a monoplacophoran mollusk have been identified. The colored circles in the branch nodes represent the last common ancestor of the monophyletic clades Conchifera, Aculifera, and Mollusca, respectively. It is important to note that the figure does not depict the chromosomal organisation of the Hox and ParaHox genes in the studied species. Thus, it is well possible (and in case of the cephalopod Idiosepius even likely) that the Hox complement is not organised in a distinct cluster in (some of) the species depicted herein