I'm trying to find more information on this type of fastener. It looks like a variation on a bayonet mount but I'm not exactly sure how it is locking in place.
You are correct, this connection style is called a bayonet. It is secured by pushing the two mating parts together and rotating (usually clockwise) a small amount. There is generally chamfer on the male side (shown at the tip of your arrow in the second picture) which allows the two parts to locate easily and when rotated, this chamfer pulls the two parts together.
It is generally a very useful mechanism for quick-release connections, and can be used to make an air-tight join when combined with the use of a seal, for example an o-ring.