Two morphologically cryptic species have until now been treated under the name Tibicen dorsatus (Say). T. dorsatus is redescribed, and a neotype is designated from topotypic material collected from Atchison County, KS. Tibicen tremulus sp. n. is described and diagnosed from T. dorsatus and from similar species by using the shape of the male claspers and color pattern. Calling songs of the males are distinct, as evidenced by field recordings of multiple individuals of both species. Males of T. dorsatus produce a rattling song, during which syllables are repeated at a rate of 38.9 ± 1.7 s⁻¹ and are broadcast over a constant carrier frequency band of 2.6–12.7 kHz, 4.0 ± 0.3 kHz at maximum amplitude. The main portion of the song of T. tremulus consists of amplitude and frequency modulated syllables repeated at a rate of 16.2 ± 0.6 s⁻¹, frequency 5.4 ± 0.3 kHz at maximum amplitude. During these modulations, amplitude increases and a base frequency range of 3.9–5.8 kHz broadens to 3.6–7.7 kHz for a duration of 19.7 ± 2.7 ms. Dorsoventral movements of the male abdomen accompany the amplitude and frequency modulations in T. tremulus, a behavior not observed in singing males of T. dorsatus. Museum records show T. dorsatus to be widespread in the prairie biome of the central United States. T. tremulus occurs west of −97° longitude, where it seems to be widely if not entirely sympatric with T. dorsatus.