The first part of a binomial is the generic name, the genus to which the species belongs. The second part is either called the specific name (a term used only in zoology) or the specific epithet (the term used in botany, which can also be used in zoology). usable definition of the word species and reliable methods of identifying particular species are essential for stating and testing biological theories and for measuring biodiversity, though other taxonomic levels such as families may be considered in broad-scale studies.