Mitochondrial gene orders for nine malacostracan crustaceans. The style of the figure is adapted from Figure 1 of Lavrov et al. . Protein and ribosomal RNA genes (large boxes) are abbreviated as in the text. Transfer RNA genes are abbreviated with single letter codes (see Figure 1). The striped box represents the AT-rich region. The ancestral pancrustacean gene order is found for five of the nine taxa, including Squilla mantis. The position of AT-rich region 1 in the S. mantis genome is noted with an arrow. Genes are transcribed from right to left except when underlined. Shaded boxes indicate genes whose positions differ from their positions in the ancestral pancrustacean sequence. The number in parentheses next to taxa names represents the minimum number of rearrangement events that separates that gene arrangement from the ancestral pancrustacean gene order (see Miller et al.  for a fuller discussion of the rearrangements in C. destructor).