  This article continues our previous study of level dynamics in the
[O(6)-U(5)]$\supset$O(5) transition of the interacting boson model
[nucl-th/0504016] using the semiclassical theory of spectral fluctuations. We
find classical monodromy, related to a singular bundle of orbits with infinite
period at energy E=0, and bifurcations of numerous periodic orbits for E>0. The
spectrum of allowed ratios of periods associated with beta- and
gamma-vibrations exhibits an abrupt change around zero energy. These findings
explain anomalous bunching of quantum states in the E$\approx$0 region, which
is responsible for the redistribution of levels between O(6) and U(5)
multiplets.
