Grevillea pieroniae Olde (Proteaceae: Grevilleoideae: Hakeinae), a rare new species in the Triloba Group from the Stirling Range, Western Australia, and a short history of the group

Twenty-one Grevillea species currently comprise the Triloba Group sensu Flora of Australia, or Group 1 sensu The Grevillea Book. All species except the transcontinental species G. anethifolia R.Br. are distributed in south-west Western Australia. Grevillea pieroniae Olde, herein described, is currently treated as Grevillea sp. Stirling Range (D.J. McGillivray 3488 & A.S. George) by the Western Australian Herbarium. It has some affinity with Grevillea anethifolia through shared possession of similar truncate-conical to cylindrical pollen-presenters. Grevillea pieroniae is a rare species that is potentially threatened by Phytophthora cinnamomi, fire frequency, a drying climate, as well as feral and native herbivore-grazing, so requires careful assessment and ongoing monitoring. A short history of the Triloba Group is provided to give context to Grevillea pieroniae and as precursor to other related species soon to be recognised.