I apologize -- I failed to restart the computer as you asked in your instructions. I followed your instructions again and this is what I got after connecting the arduino.
blaise@king-desktop:~$ dmesg
[ 77.408032] usb 4-1: new full speed USB device using ohci_hcd and address 3
[ 77.635264] usb 4-1: configuration #1 chosen from 1 choice
[ 77.686607] usbcore: registered new interface driver usbserial
[ 77.686636] USB Serial support registered for generic
[ 77.686687] usbcore: registered new interface driver usbserial_generic
[ 77.686691] usbserial: USB Serial Driver core
[ 77.699577] USB Serial support registered for FTDI USB Serial Device
[ 77.699662] ftdi_sio 4-1:1.0: FTDI USB Serial Device converter detected
[ 77.699710] usb 4-1: Detected FT232RL
[ 77.699715] usb 4-1: Number of endpoints 2
[ 77.699719] usb 4-1: Endpoint 1 MaxPacketSize 64
[ 77.699724] usb 4-1: Endpoint 2 MaxPacketSize 64
[ 77.699728] usb 4-1: Setting MaxPacketSize 64
[ 77.701241] usb 4-1: FTDI USB Serial Device converter now attached to ttyUSB0
[ 77.701285] usbcore: registered new interface driver ftdi_sio
[ 77.701290] ftdi_sio: v1.5.0:USB FTDI Serial Converters Driver
After I did this, I opened the arduino IDE and did not see the USB connection under tools -> serial ports.
I left the ide running and disconnected, then reconnected the arduino -- still no change in the serial port options.