A BIOGEOGRAPHICAL ANALYSIS OF THE TASMANIAN ENDEMIC PTUNARRA BROWN BUTTERFLY, OREIXENICA-PTUNARRA COUCHMAN (LEPIDOPTERA, NYMPHALIDAE, SATYRINAE)

Considerable geographic variation occurs in the Tasmanian endemic butt erfly, Oreixenica ptunarra, and there is a high correlation between cl usters of morphological characters and ecological factors, especially climate and elevation. Evidence is presented for the existence of a lo ngitudinal dine in phenotypic characters of wing pattern and size, whi ch is unrelated to the modest amount of variation in the male genitali a (a possible surrogate for genetic variability). Butterflies from war mer, less cloudy eastern Tasmania are larger and less dark in colour t han those from the west, culminating in the small dark populations of the north-west. This suggests selection for efficiency in thermoregula tion as climatic conditions become more marginal for adult activity fr om east to west. The prevailing subspecies classification does not ful ly reflect the range of variation in this species. Conservation strate gies that aim to guarantee the survival of the collective phenotype of O. ptunarra based on this taxonomy are therefore misinformed. The nor th-west populations are disjunct geographically and in features of phe notype, but are not especially discrete in the morphology of the male genitalia. We propose that the subspecies angeli Couchman and roonina Couchman be reduced to synonymy with nominotypical ptunarra Couchman, and a new subspecies should be recognised to incorporate populations f rom the montane grasslands of northwestern Tasmania.