Cartan subalgebras of matrix algebras over fields and division algebras

Question

Let $D$ be a division algebra and $n\in \mathbb{N}$. If $D$ is a field, then it is well-known that the diagonal-matrices form a Cartan subalgebra of $gl(n,D)$. Is there a complete description of all Cartan subalgebras?

Answer 1

partial answer was given on mathoverflow