Tetratheca spenceri R.Butcher & Cockerton

The new species of Tetratheca Sm. described herein was discovered opportunistically by Goldfields resident Charlie Spencer while exploring the Coolgardie bioregion in late 2011; it is named T. spenceri R.Butcher & Cockerton in honour of him. Tetratheca spenceri is currently known from a single population on a laterite outcrop south-east of Coolgardie and is of conservation significance. Five rare, short-range endemic Tetratheca taxa are already known from Banded Iron Formation ranges in the Coolgardie bioregion. Tetratheca spenceri can be distinguished from all other species of Tetratheca in the region by its combination of straight, finely wrinkled, glaucous stems, alternate, appressed, narrowly deltoid scale-leaves, moderately long peduncles bearing long, glandular hairs, uniformly pink petals, two ovules per locule, which are crowded together near the apex of the septum, and narrowly obovate, glabrous fruit. The new species is described and illustrated herein, its affinities are discussed, and its distribution mapped. A key to the ‘leafless’ taxa of Tetratheca in Western Australia is included.