Previously, the genus Stylogomphus in North America was believed to contain only a single species, S. albistylus. We present evidence for recognizing a second species, S. sigmastylus sp. nov.: holotype ♂, allotype ♀: Big Swan Creek, near Gordonsburg Church of Christ, Lewis County, Tennessee, 11 June 1990, C. Cook leg., deposited in the Florida State…