A critical study of Gomphus modestus Needham, 1942, with notes on related species (Anisoptera: Gomphidae)

Gomhus (Gomphurus) modestus Needham has often been confused with other species of the Gomphurus group. The penis is shown to be a good specific character in this group. The flagella of modestus are short, not long as in G. vastus Walsh with which Needham compared his species. The males of modestus have penes very much like G. dilatatus Rambur, but the subgenital plates of the females are most like G. lineatifrons Calvert. The brownish G. vastus from Texas is here considered the end of a clinal variation in color of this species. Similar dines are suggested for Gomphus (Stylurus) townesi Gloyd, and G. (Stylurus) plagiatus Rambur. G. flavocaudatus Walker is certainly the light end of a clinical variation in color of G. exilis Selys. The need is shown for further study of the relationship between the darker G. brimleyi Muttkowski found from North Carolina to north-western Florida and the yellower G. cavillaris Needham from central and southern Florida.