Mitochondrial gene order of Nemertea and selected lophotrochozoan species. Colour coded genes show different positions from that seen in Lineus viridis, according to transpositions (green) or inversions (yellow, orange). The yellow inversion is a potential synapomorphy. tRNA genes are abbreviated by their amino acids (one letter code). Upper genes are plus-strand encoded, lower genes are minus-strand encoded. Gene orders according to the following references: Cephalothrix , Terebratulina , Ilyanassa , Katharina , Phoronis , Entoprocta .