Flagellar microstructures of male tiger beetles (Coleoptera: Cicindelidae): implications for systematics and functional morphology
AbstractA comparison of appressed teeth-like structures, coined tempers, on the flagellum of the male internal sac among 10 North American and one Asian species of tiger beetles is consistent with earlier proposed genera of Cicindela Linné, ranked here as subgenera. Based on scanning electron photomicrographs, observations revealed that the flagellum has a single groove along its whole length, with tempers in the groove, and for most species tempers are present only on one side of the ungrooved flagellar surface; tempers point basally (proximally) both on the flagellar surface and within the flagellar groove; and a distributional pattern of the tempers appears to be unique to each subgenus. The species Cicindela punctulata Olivier and Cicindela lepida Dejean have a lumen in place of a flagellar groove, the former with tempers on the ungrooved flagellar surface and the latter without. Tempers on the ungrooved surface of the flagellum are assumed to grip the inner wall of the spermathecal duct while penetrated by the flagellum during insemination or preinsemination clearing. The presence of tempers on one side of the flagellum promotes rapid, smooth insertion and removal of the flagellum from the duct. It is proposed that tempers of the flagellar groove assist the flow of seminal materials to the spermatheca by guiding the narrow neck of the spermatophore into the spermathecal duct while the flagellum is inserted.