Aminergic receptors: S. mediterranea and S. mansoni. Neighbor-joining tree (bootstrap value = 500) of putative aminergic GPCRs. Included in this analysis are 21 (of 24) S. mansoni and 57 (of 66) S. mediterranea full-length and near full-length aminergic receptors, alongside 14 known C. elegans amine receptors. The latter grouping includes receptors that respond to tyramine, octopamine, dopamine, serotonin, and acetylcholine . Branch lengths are scaled to bootstrap support, branches terminating in Schistosoma receptors are shown in green, and branches terminating in Schmidtea receptors are shown in blue. Flatworm receptors are outlined (solid lines) and classified by ligand with respect to their nearest-related C. elegans homologs. Two diverged flatworm-specific receptor groupings are outlined with a dashed line.