Egami spotted a Tamron lens design patent. Teh design and the specs are exactly the ones of the Zeiss Batis 18mm f/2.8 lens. So it looks like Tamron designed that Zeiss lens too (yes also may other Zeiss lenses have a Tamron design). Anyway, not really a big deal: This lens is supersharp and one of the best lens you can buy today.
Zeiss Batis 18mm f/2.8 at [shopcountry 47045].