  We study manifestations of spin-charge separation (SCS) in transport through
a tunnel-coupled interacting single-channel quantum ring. We focus on the
high-temperature case (temperature $T$ larger than the level spacing $\Delta$)
and discuss both the classical (flux-independent) and interference
contributions to the tunneling conductance of the ring in the presence of
magnetic flux. We demonstrate that the SCS effects, which arise solely from the
electron-electron interaction, lead to the appearance of a peculiar fine
structure of the electron spectrum in the ring. Specifically, each level splits
into a series of sublevels, with their spacing governed by the interaction
strength. In the high-$T$ limit, the envelope of the series contains of the
order of $T/\Delta$ sublevels. At the same time, SCS suppresses the tunneling
width of the sublevels by a factor of $\Delta/T$. As a consequence, the
classical transmission through the ring remains unchanged compared to the
noninteracting case: the suppression of tunneling is compensated by the
increase of the number of tunneling channels. On the other hand, the
flux-dependent contribution to the conductance depends on the
interaction-induced dephasing rate which is known to be parametrically
increased by SCS in an infinite system. We show, however, that SCS is not
effective for dephasing in the limit of weak tunneling. Moreover, generically,
in the almost closed ring, the dephasing rate does not depend on the
interaction strength and is determined by the tunneling coupling to the leads.
In certain special symmetric cases, dephasing is further suppressed. Similar to
the spinless case, the high-$T$ conductance shows, as a function of magnetic
flux, a sequence of interaction-induced sharp negative peaks on top of the
classical contribution.
