The taxonomy, ecology and conservation status of the Golden-rayed Blue: A threatened butterfly endemic to western Victoria, Australia

The Golden-rayed Blue, Candalides noelkeri sp. nov. (Lepidoptera: Lycaenidae), from the Wimmera of western Victoria, Australia, is described and illustrated. The male and female genitalia and immature stages are figured, described and compared with those of Candalides heathi and C. xanthospilos. Candalides noelkeri sp. nov. is placed in the C. xanthospilos species-group, being most closely allied to and allopatric with C. heathi. It is predominantly univoltine, with adults usually present from late November to early February. However, it has a facultative pupal diapause that gives rise to a partial overlapping second generation in mid-summer. The species is ecologically specialized, monophagous and has a narrow geographical range, currently known only from two localities in a restricted area near Natimuk. Within this limited area it is restricted to flood plains bordering natural salt-lakes where the larval food plant, a prostrate form of Myoporum parvifolium (Myoporaceae), grows as a low spreading ground cover plant. Morphological and geological evidence suggest a recent (late Pleistocene) allopatric speciation event between C. noelkeri sp. nov. and C. heathi. The small, peripheral spatial distribution of C. noelkeri sp. nov. implies that differentiation has been achieved by the founder effect, either through peripheral isolates speciation (peripatric speciation) or postspeciation dispersal, possibly as a result of a barrier created by the volcanic plains in western Victoria. Available information indicates that C. noelkeri sp. nov., Victoria's only endemic species of butterfly, is facing a high risk of extinction and accordingly its conservation status should be considered as Endangered. The most serious threat at the type locality is habitat change or succession caused by invasion of Melaleuca halmaturorum, which is creating a dense shaded paperbark forest that is reducing both the preferred open sunny microhabitat and the extent of the larval food plant. Recognition of C. noelkeri sp. nov. as a flagship taxon is likely to enhance the conservation of biodiversity in remnant flood plain/salt-lake ecosystems of temperate south-eastern Australia.