A word in the scientific name of an animal or a plant following the name of the genus and denoting a species, variety, or other division of the genus, as sativa in Lactuca sativa.

• 种名部分接在属名之后的动物或植物的科学名称，指一个种、变种或属下面的其它类别，如家莴苣在莴苣属、家莴苣种中