There are a few other documented versions of this issue, but they are all related to the older versions of XAMPP that suggest adding unset DYLD_LIBRARY_PATH to the startup manager, this is already added in 1.8.3-5, Another suggests starting mysql from the terminal, which gives me an error.
/Applications/XAMPP/xamppfiles/bin/mysql.server start
Starting MySQL
. ERROR! The server quit without updating PID file (/Applications/XAMPP/xamppfiles/var/mysql/stn04.local.pid).
There are no other versions of MySQL running in activity monitor.