Short-range endemic (SRE) invertebrates are animals that display restricted geographic distributions, nominally less than 10,000 km2, that may also be disjunct and highly localised.
Isolating mechanisms and features such as roads, urban infrastructure, large creek lines and ridges can act to prevent the dispersal and gene flow of the less mobile invertebrate species.
Several animal groups studied in Australia consist largely of short-range endemics, including freshwater and terrestrial gastropods (snails and slugs), earthworms, velvet worms, mygalomorph spiders, schizomids, millipedes, phreatoicidean crustaceans, and freshwater crayfish.
The uncertainty in categorising a specimen as SRE originates in a number of factors including: Life stages of species that cannot be identified at the species level, e.g. some females and juveniles, are assessed based on the knowledge of the higher taxon they belong to, i.e. family or genus.
For example, all juvenile or female Antichiropus millipedes would be classified as 'confirmed SRE' as all but two of the 120+ known species in this genus are considered SREs.