Phylogenetic trees of candidate ionotropic receptors (IRs, IGluRs, and VIGluRs), A is the ML phylogenetic tree and B is the NJ phylogenetic tree. Includes sequences from Procambarus clarkii, Litopenaeus vannamei, Eriocheir japonica sinensis, and other Decapoda. IRs font is colored red; IGluRs font is colored blue; VIGluRs font is colored black. Moreover, the region containing IR co-receptors are colored yellow or orange.