fuel pipe

When i fill the tank up on my c230 I have discovered a leak on a hose that comes from the filler cap. Anyone any ideas what the pipe is called or a part number?

Hi Guys. I have a C220 CDI Auto, on a 2001. Recently i have been coming up with numerous little issues. Anyways, not so long ago i had a fuel pipe replaced which cost me about £28 (In the photo the prominant black ribbed pipe). However i now suspect its the pipe i have cricled in red...