Stylidium spathulatum R.Br. (n=14) is lectotypified and a revised species description provided. On the basis of cytological and morphological evidence Stylidium planirosulum Wege (n=13) and S. glandulosissimum Wege (n=13) are described as new. A third morphologically allied species with conservation priority, Stylidium gloeophyllum Wege, is also described. Variation in trichome structure and distribution is shown to be highly diagnostic. Illustrations are provided for the three new species.