syntype

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun One of two or more biological specimens or other elements used for the original published description of a species or subspecies when no holotype was designated.
• noun One of two or more biological specimens or other elements simultaneously designated as type specimens in the original published description of a species or subspecies.

from The Century Dictionary.

• noun In the nomenclature of types in natural history, any specimen of the original series (from which a species has been described and named) when there is no holotype: same as cotype.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun biology Any of several specimens selected as types for the name of a species