ABSTRACT
Some species have an extremely restricted (microendemic) distribution, living as a single population in a small area. The Devil’s Hole pupfish (Cyprinodon diabolis) is restricted to one thermal spring issuing from a mountainside in south-west Nevada (Moyle and Williams 1990). The Amargosa vole (Microtus californicus scirpensis) lives in a single watershed in California, United States (Murphy and Freas 1988). The rare black hairstreak butterfly (Strymonidia pruni) is confined to a few sites in central England and in central and eastern Europe.
