Biological classification. It ranks below family and above species, consisting of structurally or phylogenetically (see phylogenetic tree) related species or a single species exhibiting unusual differences. For example, the species of roses collectively form the genus Rosa and those of horses, donkeys, and zebras form the genus Equus. The genus name, capitalized and usually italicized, is the first word of a scientific name in the system of binomial nomenclature.
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Members of the southeast Asian planthopper genus Ancyra are well-known for having a pair of prolonged filaments at the tips of the forewings that arise near a pair of small glossy spots; this creates the impression of a pair of antennae, with corresponding "eyes" (a remarkable case of automimicry). The "false head" effect is further reinforced by the bugs' habit of walking backwards when it detects movement nearby, so as to misdirect predators to strike at its rear, rather than at its actual head.