Biology, distribution, and conservation of the Gamilaroi crayfish Euastacus gamilaroi Morgan, 1997 (Decapoda: Astacidea: Parastacidae), a freshwater crayfish from New South Wales, Australia

Euastacus gamilaroi Morgan 1997, the Gamilaroi crayfish, was initially described based on specimens collected in 1954 from Hanging Rock, New South Wales, but since then scant subsequent records hinder conservation of this endangered species. Extensive sampling during 2006-2023 delineated the distribution, habitat preferences, biological traits, and conservation status of the species. Together with concurrent molecular taxonomic analyses were extend the species range from headwater regions of highland streams above 960 m altitude of Burrows Creek to include highland streams of Duncan and Dungowan creeks (Peel-Namoi River/western drainage) and Tomalla, Back, and Ben Halls creeks (Barnard-Manning River/eastern drainage). We provide information on the distribution, biology, and ecological associations of the species. Results advocate for the classification of E. gamilaroi as an endangered species, recognizing its distinctive ecological niche and its status as a climate refugee, aiming to protect this rare species from climate-related challenges. We also present a taxonomic key differentiating E. gamilaroi from other species of Parastacidae in the region.