Original combination

In the scientific name of organisms, basionym or basyonym (from Greek βάσις basis "base" + ὄνυμα onyma "name") means the original name on which a new name is based. The term original combination or protonym is used in the same way in zoology.Bacteriology uses a similar term, basonym, spelled without an i.

The term "basionym" is used in botany only for the circumstances where a previous name exists with a useful description, and the International Code of Nomenclature for algae, fungi, and plants does not require a full description with the new name. A basionym must therefore be legitimate. Basionyms are regulated by articles 6.10, 7.3, 41, and others.

The basionym of the name Picea abies (the Norway Spruce) is Pinus abies. The species was originally named Pinus abies by Linnaeus. Later on, botanist Karsten decided this species should not be grouped in the same genus (Pinus) as the pines, so he transferred it to the genus Picea (the spruces). The new name Picea abies is combinatio nova, a new combination (abbreviated comb. nov.).

In 1964, the subfamily name Pomoideae, which had been in use for the group within family Rosaceae that have pome fruit like apples, was no longer acceptable under the code of nomenclature because it is not based on a genus name. Claude Weber did not consider the family name Malaceae Small to be taxonomically appropriate, so he created the name Maloideae at the rank of subfamily, referring to the original description of the family, and using the same type. This change of rank from family to subfamily is an example of status novus (abbreviated stat. nov.), also called a "name at new rank".

...
Wikipedia