Manifestation of riddling in the presence of a small parameter mismatch between coupled systems.

Riddling bifurcation, i.e., the bifurcation in which one of the unstable periodic orbits embedded in a chaotic attractor becomes unstable transverse to the attractor, leads to the loss of chaos synchronization in coupled identical systems. We discuss here the manifestation of the riddling bifurcation for the case of a small parameter mismatch between coupled systems. We show that for slightly nonidentical coupled systems, the transverse growth of the synchronous attractor is mediated by transverse bifurcations of unstable periodic orbits embedded into the attractor. The desynchronization mechanism is shown to be similar to the case of chaos-hyperchaos transition.