Thanks for you comments, which are very helpful!
I find it interesting that this special graphical notation, which is so established in the Bayesian community and especially in the PyMC community, seems to be a mix of different diagram types (Bayesian network, Kruschke diagram, Plate notation), but obviously neither has a name nor some complete documentation. Seems like Jesse’s description is the most complete documentation for this so far.
I probably perceive it like this because I do not have a long background in Bayesian modeling and am now starting this journey in the PyMC context. Most of you probably have already experience with other probabilistic languages and have read more literature about this, so that it just looks natural to you.
May the force be with you
Matthias