  We perform extensive molecular dynamics simulations of a highly charged
flexible polyelectrolyte (PE) chain in a poor solvent for the case when the
chain is in a collapsed state and the electrostatic interactions, characterized
by the reduced Bjerrum length $\ell_B$, are strong. We detect the existence of
several sub-regimes, $R_g \sim \ell_B^{-\gamma}$, in the dependence of the
gyration radius of the chain $R_g$ on $\ell_B$. In contrast to a good solvent,
the exponent $\gamma$ for a poor solvent crucially depends on the size and
valency of counterions. To explain the different sub-regimes we generalize the
existing counterion fluctuation theory by a more complete account of the volume
interactions in the free energy of the chain. These include interactions
between the chain monomers, between monomers and counterions and the
counterions themselves. We also demonstrate that the presence of the condensed
counterions can modify the effective attraction among the chain monomers and
impact the sign of the second virial coefficient.
