PlantFiles: Tsuru Holly
Ilex rugosa

Ilex rugosa is native to Northern Japan and Korea. It is a very low, spreading Holly with large bright red berries, leaves about 3" with fine, indented serrations that suggest the spines of other Hollies. The name rugosa probably refers to the kind of wrinkled appearance of the leaves, like some leathers. Not a dark green color.
For these characteristics, Kathleen Meserve of Long Island, New York chose this plant to cross with other hollies to produce cold hardier hybrids.
The resulting crosses with English Holly, Ilex aquifolium, became known as the Blue Hollies - Ilex x meserveae 'Blue Boy' and 'Blue Girl', 'Blue Prince' and 'Blue Princess', etc.

Apparently it is uncommon in cultivation in the United States, but a few arboretums have examples.