Lens Mount Identification
Canon 'new' FD
Contax & Yashica
Kodak Retina Reflex
Leica R ROM
Petri only made one lens mount. They also used M42 mounts. Some Petri lenses have Pentax K mounts. Those were actually made by Cosina and not Petri. Petri bayonet and M42 mount lenses are excellent. The Cosina made lenses are not the same quality, though.
This scenario was not unusual. Cosina made many cameras and lenses for failing and successful brands. Nikon's FM10 is 100% Cosina.
The Sigma mount has two variations. The first version has two bayonets to support heavy lenses. That feature was not actually used so they remove the extra bayonet with the introduction of the SD14. All Sigma AF bodies use the Sigma bayonet mount. Early Sigma MF bodies used Pentax mounts.