  Systematic microcanonical inflection-point analysis of precise numerical
results obtained in extensive generalized-ensemble Monte Carlo simulations
reveals a bifurcation of the coil-globule transition line for polymers with a
bending stiffness exceeding a threshold value. The region, enclosed by the
toroidal and random-coil phases, is dominated by structures crossing over from
hairpins to loops upon lowering the energy. Conventional canonical statistical
analysis is not sufficiently sensitive to allow for the identification of these
separate phases.
