C-projective symmetries of submanifolds in quaternionic geometry

The generalized Feix-Kaledin construction shows that c-projective 2n-manifolds with curvature of type (1,1) are precisely the submanifolds of quaternionic 4n-manifolds which are fixed-point set of a special type of quaternionic circle action. In this paper, we consider this construction in the presence of infinitesimal symmetries of the two geometries. First, we prove that the submaximally symmetric c-projective model with type (1,1) curvature is a submanifold of a submaximally symmetric quaternionic model and show how this fits into the construction. We give conditions for when the c-projective symmetries extend from the fixed-point set of the circle action to quaternionic symmetries, and we study the quaternionic symmetries of the Calabi and Eguchi-Hanson hyperkahler structures, showing that in some cases all quaternionic symmetries are obtained in this way.