Malazan Empire: Dumb House Paran thought.. - Malazan Empire

Okay, i've spent the greater part of a month worrying about this..

Why is Ganoes Paran known as his surname 'Paran'.. and both Felisin and Tavore known by their first names?
ie..why not Adjunct Paran ?

i will feel real stupid if i got his name backwards..but they always refer to it as the House Paran.
blinky