  We prove that any Borel Anosov representations of a surface group into
$Sp(4,\mathbb{R})$ that has maximal Toledo invariant must be Hitchin. We also
prove that a representation of a surface group into $Sp(2n,\mathbb{R})$ that is
$\{n-1,n\}$-Anosov is maximal if and only if it satisfies the hyperconvexity
property $H_n$.
