There's a Mad Hoosa's Shield found in a store in Old Ebonheart, a shield from Hammerfell to be exact. 

The issue is more of a conflict of lore, specifically between Valenwood and Beyond Skyrim. Mad Hoosas is a replacement for Medusas, found within BS's Hammerfell lore (I believe it was originated from BS lore, but I honestly couldn't find anything to confirm or deny that with a quick google search) - and has then found its way into TR. The conflict moreso comes from Valenwood, which is planning on having its own replacement for Medusas (Medritha, current working title), which are very different from the Mad Hoosas of Beyond Skyrim.

I suppose the correction would be either

-Decide to use both (Mad Hoosas and Medrithas being two separate, but similar creatures found in two separate provinces). 

-Change the name of the shield.

Turns out Mad Hoosas come from TR Hammerfell in Oblivion. The "both" option it is imo.