Please help can someone please help figure out how this type of thread called?

I don't think you'll find any charts, tables, or references for a feature like that. It is really custom made for the application. What fits, how secure, how much rotation, how much force, friction fit vs. detents.... There are a hundred variables to account for, and it won't be the same on a second device.

As a starting point, maybe try a regular thread. You can always extend the thread profile to stick way out like it does in the image. You'd have to experiment a bit with the pitch, but once you had one "fin" made, it would be easy to pattern the remainder.

The overall appearance is similar to a triple start or triple lead thread: http://www.mmsonline.com/columns/dealing-with-multiple-start-threads-on-turning-centers

What did you find it on?
I don't think it is an actual "thread" as in you'll find a table listing its major and minor diameters along with pitch and clearances. It looks more like a "thread like" feature to create a twist lock mechanism.

The best option might be to reverse engineer it with calipers, and some photos. Laser scanning can help. but seems a little overboard for this application.

this looks like it is not a standard thread so i would be surprised if there are any thread specs anywhere, this will have been a one off as it is just for locking and is not a full thread.