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If the races are sufficiently different or if they have been tested to show little genetic connection regardless of phenotype, two or more groups/races can be identified as subspecies, which is an official biological taxonomical unit subordinate to species. If not, they are denoted as races, which means that a taxonomic rank should not be given to the group, or taxonomists are unsure whether or not a formal rank should be given.
According to Ernst W. Mayr, "a subspecies is a geographic race that is sufficiently different taxonomically to be worthy of a separate name."