(a) The first word denoting the genus starts with a capital letter while the specific epithet starts with a small letter In plant nomenclature (ICBN), tautonyms are not valid i.e. generic name and specific name should not be same in plants. E.g. Mangifera mangifera But tautonyms are valid for animal nomenclature (ICZN-International Code of Zoological Nomenclature) e.g. & Naja naja (Indian cobra), Rattus rattus (Rat).