No /dev/tty ports showing on Mac OS X with Arduino Uno R3

I’m brand new to Arduino and followed the ‘Getting Started w/ Arduino on Mac OS X’ guide to set everything up, but I ran into some trouble when I had to choose my Serial Port.

The guide says to use a port with /dev/tty.usbmodem in it, but when I connect the board to my computer, no /dev/tty ports appear (not even for Bluetooth). I selected the only non-Bluetooth port that appeared, /dev/cu.usbmodem1421 and everything seems to work fine (I’m able to upload sketches).

Can anybody explain why my /dev/tty ports aren’t appearing and whether or not it matters?

Cheers.

Technical Details:
Computer: 2012 MacBook Air running OSX 10.10.5 Yosemite
Board: Arduino Uno R3
IDE Version: 1.6.7

See screenshot for available ports.

The /dev/cu. and/dev/tty. devices appear to work identically and newer versions of Arduino stopped showing both in the port list. They chose to drop the /tty version.