A. irradians has popularly been divided into subspecies. Using Abbott (American Seashells 1974) as a baseline the subspecies names were:

Argopecten irradians irradians (Lamarck, 1819)
Argopecten irradians concentricus (Say, 1822)
Argopecten irradians amplicostatus (Dall, 1898)

The distribution of these three shells is displayed in the below slide. Note that despite the occasional adventitious occurrence of an A. irradians between North Carolina and Palm Beach County, Florida, (see Lee 2009) living populations of the Bay Scallop have not been documented within this “Gap.”