An account is given of the lichen genus Pertusaria in Australia, including Lord Howe Island, Norfolk Island and Macquarie Island. Keys and descriptions for the 128 species are given and the synonymy, chemistry, distribution and ecology of each species is discussed. Twenty new species are described: P. aquilonia, P. barbatica, P. boweniana, P. complanata, P. ewersii, P. georgeana, P. gundermanica, P. injuneana, P. meeana, P. nerrigensis, P. orarensis, P. pallida, P. pilosula, P. praetermissa, P. pseudothwaitesii, P. salebrosa, P. sydneyensis, P. umbricola, P. xantho-dactylina and P. xenismota .