Panulirus cygnus is a species of spiny lobster (family Palinuridae), found off the west coast of Australia. Panulirus cygnus is the basis of Australia's most valuable fishery, making up 20% of value of Australia's total fishing industry, and is identified as the western rock lobster. Taxonomy Panulirus cygnus was previously classified under several taxonomic arrangements, the description as a new species was published in 1962. The Western Australian crayfish was identified in 1916 as Panulirus penicillatus (Olivier, 1791). This was reassessed at the British Museum by Isabella Gordon in 1936 as Panulirus longipes at the request of Ludwig Glauert, a diagnosis that was conserved, despite further doubts, due to its extensive use by the state's crayfishing industry and associated legislation. The author, Ray George, recognised the similarities to other species of Panulirus in a comparative study, but proposed the anatomical characteristics were of an undescribed species. The generic name is an anagram of Palinurus, as with other genera of its nominal family Palinuridae, the spiny lobsters. The name is derived from Palinurus, mentioned in the Aeneid, whose improper burial caused his soul to drift near the coast to the open seas; an appropriate metaphor for the habits of the spiny lobsters that develop near the coast and migrate away from it. The specific epithet is named for an emblem of Western Australia, the black swan Cygnus atratus. The holotype was collected by George in a pool at Rottnest, at a depth of 1 metre, and preserved at the state's museum (WAM); other specimens in their collection were reclassified as paratypes. George's taxon was recognised as a subspecies until the 1970s, when a revision elevated the population to the rank of species. The recognition of the species was relevant to the conservation of its related fishing industry, it is unique to the region and could not be naturally repopulated from other regions. Common names of the species include "western rock lobster", "Australian spiny lobster", "crayfish" or "crays". The common names of "lobster", "homard" and "yabbie" are also used to refer to this species, along with many other crustaceans. Description The species has five pairs of legs that are used to move across the ocean floor, the fifth set possessing claws in the female, and six smaller pairs are located at the mouth. The eyes are located at the ends of stalks. They vary in colour from a brownish purple to a