What are the primes of $\mathbb{Z}[\sqrt{-p}\colon \text{$p$ prime}]$?

Question

Let $R$ denote subdomain of $\mathbb{C}$ which is isomorphic to the direct limit of the diagram of commutative rings $\mathbb{Z}\hookrightarrow\mathbb{Z}[\sqrt{-2}]\hookrightarrow\mathbb{Z}[\sqrt{-2},\sqrt{-3}]\hookrightarrow\mathbb{Z}[\sqrt{-2},\sqrt{-3},\sqrt{-5}]\hookrightarrow\dotsm$.

What is the set of primes of $R$? What is a citable reference (with proof) for this?