Neuroanatomy and neurochemistry: implications for the phylogeny of the lower Neoptera

Physiologists and developmental biologists routinely collect data that, whe n analyzed from a phylogenetic perspective, may improve our understanding o f the evolutionary relationships of many enigmatic groups of organisms. Imm unohistochemical studies of the innervation of the salivary glands provide data that clarify the evolutionary relationships of the lower Neoptera, a m ajor unresolved issue in our understanding of insect phylogeny. Support for the hypothesis that the Phasmatodea and Orthoptera are sister taxa is prov ided by the dorsal position of the cell body of salivary neuron 1 in the su besophageal ganglion and the presence of serotonin in salivary neuron 2.