Two reciprocally monophyletic mitochondrial clades of the commercially valuable jellyfish Catostylus mosaicus are endemic to south-eastern Australia. Here, medusae in the two clades are shown to differ also in colour and in the dimensions of their papillae, oral disk, and bell depth. They are referred to two varieties recognized in 1884 by von Lendenfeld. The clade occupying localities adjacent to Bass Strait is redescribed as subspecies C. mosaicus conservativus; the clade from New South Wales and southern Queensland spans the type locality (Port Jackson) of C. mosaicus and is designated C. mosaicus mosaicus. Their ecology and colour, in the context of von Lendenfeld's original descriptions, and the implications for fisheries are discussed.