Comparative morphology of female gonapophyses IX in Delphacidae (Hemiptera: Auchenorrhyncha: Fulgoromorpha) with key to tribes.

Diagnoses for delphacid species rely on male genitalia, with female structures rarely considered. In this study, we examined gonapophyses IX from 36 exemplar species, representing all 14 tribes of Delphacidae. From these 36 species, we found 53 potential synapomorphies. We present a key to delphacid tribes that integrates gonapophyses IX features. We hypothesize that the basal delphacids, the Asiracinae, have teeth concentrated at the apex to make short incisions into soft plant tissue. In Vizcayinae, these teeth are greatly reduced, extending past the apex, and may function to pierce host tissue. In Plesiodelphacinae, these teeth are increased in size and number, potentially to function as a saw. In Kelisiinae, teeth size is reduced, while teeth frequency is increased subapically. Finally, in the Stenocraninae and Delphacinae, the most derived lineages, an increase in tooth size and shape may have developed to cut into graminoid hosts with high concentrations of silicate.