Euastacus fetzneri sp. nov., a new highly range restricted dwarf spiny freshwater crayfish (Crustacea: Decapoda: Parastacidae) from the upper Nerang River, Southeast Queensland, Australia, with a conservation assessment and recommendations.
Abstract
The Australian freshwater spiny crayfish genus Euastacus Clark, 1936 is the most speciose genus of the family Parastacidae, with 56 species currently described. A new species of dwarf spiny crayfish, Euastacus fetzneri sp. nov., is described from the uppermost headwaters of the Nerang River catchment in southeast Queensland, Australia. The species represents the most habitat-restricted freshwater crayfish known globally. This groundwater-dependent species inhabits a narrow seepage zone, with its known distribution largely restricted to stretches of less than 70 metres of stream channel below four permanent subterranean emergence points. Morphologically and genetically allied to the geographically proximate E. binzayedi and sympatric with the dwarf-group E. maidae, E. fetzneri is distinguished by the presence of four mesial carpal spines on the major cheliped (versus three in E. binzayedi) and a large, sharp ventral carpal spine (versus obsolete or absent in E. maidae), and unique genetic markers. Ecological observations, burrowing behaviour, and biological notes are provided. Given its extremely limited distribution, small population size, and the high vulnerability of its habitat to disturbance, E. fetzneri meets IUCN Red List criteria as Critically Endangered (CR B1ab(iii, iv)).
