Leberis aenigmatosa Smirnov, which belongs to a monotypic genus endemic to Australia, is fully redescribed from material collected from granite rock-pools in Western Australia. All three male instars are described for the first time. The redescription includes an extensive series of line drawings. Leberis shows some affinity with the genus Celsinotum Frey of eastern Australia. There is strong evidence for isolation and radiation of eastern and western chydorid populations.