I found this:
"As Ian Lyons said, some of the papers you want to use aren't supported by the 21/2200.
But note that the media list changes (on the Mac platform, anyway)
depending on which black cartridge you're using, MatteBlack or Photo Black."
Best regards --Gernot Hoffmann
I should have mentioned that I found that page from Ian Lyons earlier too. The strange thing is that I had access to those media types in an older version of OS X and I'm using the Photo Black Cartridge at the moment so glossy and semigloss should be there. I have Windows 10 installed as a virtual machine on the same Mac (running under VMWare Fusion) and when changing to Windows, I have access to both Glossy and Semigloss Paper so it seems to have something to do with the OS X driver. The latest OS X Intel driver from Epson Stylus Photo 2100 : Drivers & Software did not change anything either.
It was not a Photo Black Cartridge I had installed. It was a Matte Black so now it makes sence! D'OH!