The relationships among rare ‘leafless’ species of Tetratheca Sm. occurring on banded ironstone ranges near Koolyanobbing, Western Australia, and allied, unclassified, populations from Eneabba, Newdegate and the Die Hardy Range have been assessed by molecular characters. These findings, in conjunction with morphological investigations, have identified a new species and two new subspecies from within the ‘T. aphylla group’ and these are formally described here. Tetratheca nephelioides R.Butcher, is geographically restricted to the Eneabba area and has close morphological affinity to T. aphylla F.Muell. Tetratheca aphylla subsp. megacarpa R.Butcher, is restricted to the Newdegate area, some 300 km south of the only known populations of T. aphylla subsp. aphylla in the Helena and Aurora Range. Tetratheca paynterae Alford subsp. cremnobata R.Butcher is restricted to the Die Hardy Range, c. 10 km north-east of the only known population of T. paynterae subsp. paynterae at ‘Windarling’. All of these taxa are recognised as Declared Rare Flora. In the process of updating the existing key to ‘leafless’ species of Tetratheca to include these new taxa, two additional new species were identified from within collections of T. nuda Lindl. These are described here as T. angulata R.Butcher and T. applanata R.Butcher. Images and distribution maps for all taxa are provided.
