tribus

Tribus, Latin for “tribe,” designates a taxonomic rank used in biology to group related genera within a family. The rank sits below subfamily and above genus in zoological classification, and likewise in botanical classification where tribes are used to subdivide families. In zoology, tribe names are typically formed with the suffix -ini, such as Hominini for the tribe that includes Homo and Pan within the family Hominidae. In botany, the corresponding tribe names commonly end with -eae, such as Andropogoneae in Poaceae.

Etymology and history: Tribus comes from Latin tribus, meaning “a tribe, a crowd, or a group.” The term was adopted into scientific taxonomy in the early modern period to denote an intermediate rank that helps reflect evolutionary relationships when enough data exist to partition a group at a level smaller than a subfamily but larger than a genus. The rank is used variably across organisms; some groups have extensive tribal classifications, others rely on subtribes or clades instead.

Usage and scope: Not all groups employ the rank; its use varies by literature and taxonomy. When used, tribes are often defined by a combination of morphological, molecular, and phylogenetic evidence. In some groups the boundaries between tribes can be controversial or poorly resolved, reflecting ongoing advances in systematic biology.

Other senses: Outside biology, tribus or tribus historically referred to political divisions of citizens in ancient Rome (comitia tributa). The term remains a Latin root in many European languages and continues to influence the English word “tribe.”