What is the default terminal (shell) for Xubuntu?
All Ubuntu variants use Bash as their default shell. They all use different terminal emulators. However, Xubuntu uses the Xfce 4 terminal emulator (Kubuntu uses konsole and Ubuntu gnome-terminal).
You can always use "echo $SHELL" to get current shell environment.
It's called Terminal, but it's different from the Gnome Terminal.
See What is Terminal - Xfce