2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/105021We investigate the integrability of almost complex structures on the twistor space of an almost quaternionic manifold constructed with the help of a quaternionic connection. We show that if there is an integrable structure it is independent on the quaternionic connection. In dimension four, we express the anti-self-duality condition in terms of the Riemannian Ricci forms with respect to the associated quaternionic structure.LaTeX, 12 pages, no figuresDifferential GeometryHigh Energy Physics - TheoryMathematical Physics53C25; 53C15text