  We prove a {\Gamma}-equivariant version of the algebraic index theorem, where
{\Gamma} is a discrete group of automorphisms of a formal deformation of a
symplectic manifold. The particular cases of this result are the algebraic
version of the transversal index theorem related to the theorem of A. Connes
and H. Moscovici for hypoelliptic operators and the index theorem for the
extension of the algebra of pseudodifferential operators by a group of
diffeomorphisms of the underlying manifold due to A. Savin, B. Sternin, E.
Schrohe and D. Perrot.
