New species and new circumscriptions in Stylidium (Stylidiaceae)

The following four triggerplants from south-west Western Australia are newly described: Stylidium applanatum Wege, S. bellum Wege, S. diademum Wege and S. rosulatum Wege. Stylidium luteum R.Br. subsp. clavatum Carlquist is raised to species level, S. squamellosum DC. and S. striatum Lindl. are redefined, S. rigidifolium Mildbr. is placed into synonymy under S. striatum, and S. zeicolor F.L.Erickson & J.H.Willis is reinstated. With the exception of S. zeicolor and S. diademum, all of these species have a conservation listing.