I'm stumped. I usually use these two guides. Had a quick look and didn't see it, but you may want to look in more detail: KEH Camera Blog: The Lens Mount Guide: Part 1 SLR Lens Mount Identification Guide
It's hard to tell if those three little wings are part of the mount or not. The rest of it looks a bit like an m42 screw mount.
Looks like a Petri lens mount according to the second link above, it has the same lens position protuberance on the lower left.
+1 The images I've seen of the Petri mount seem to be identical to that lens, however the aperture lever on your lens photo seems to be missing. Perhaps it's an earlier variant with no Auto-Aperture capability, or it may have been modified (removed) for use in video? Interesting lens though... if you've got it, it would be nice if you could post some images from it. Welcome to the forum btw, Infinex!
Perhaps this is one of Komura's Unidapter lenses with a Petri adapter already attached? Is the mount portion separate and removable?
The mount is separable and movable but there is no lens in it? bought it cheaply at 9.99usd from ebay {} {} {} Is it possible to use other adpater and glue it?
That's not the mount, that's the whole rear focusing helicoid. The mount piece would be the small silver piece on the end with the three flanges on it. If it screws off, you might have something more easily adapted underneath it. Did the seller have any idea what the mount was? Or what camera it was for?
