Natural History Collections “Rarity”
•Type or single locality only (= single “subpopulation” = single grid cell) or few collections/localities (e.g., 5 or fewer)
•Age of collection(s)
•Caveats: Taxonomic and collection artifacts
For example, natural history collections allow us to identify  “rare” species that are potentially at greatest risk of extinction and, therefore, of the highest priority for conservation action.  “Rarity” based upon natural history collections can be assigned to those species known only from a single collection (their so-called “type”) or locality (which translates into a single “subpopulation” in the parlance of IUCN Red List criteria), or from relatively few collections/localities, e.g., 5 or fewer.  Collections also carry a temporal component, such that species known only from older historical collections may deserve greater attention.  However, when we use natural history collections for conservation assessments, we must bear in mind possible artifacts stemming from both the nature of the collecting endeavor and the taxonomic process itself.