Sure there's equine_penis but not every artist draws that little straw of a protruding urethra (I guess protruding_urethra might be an alternative tag). Actually I think most of them don't, even if they've gotten everything else correct. Anyway just curious if I've missed a tag someone made for it.
Fun fact: "medial ring" is a made-up term. The proper anatomical name is "preputial ring"
"Medial ring" is actually a "structure in fission yeast".
Updated by Ryu Deacon