This seems to be a oversight that is exacerbated by the game's mechanics.
In the Elder Scrolls IV: Oblivion there is only one form of vampirism, it is likely too much effort to develop a second form of vampires for this rare exception. This is especially true when considering the vampire mechanics are so poorly tested that the quest to cure vampirism may become bugged forcing you to permanently remain a vampire. When developing a game of this scale resources cannot always be allocated to give attention to every article of lore the franchise offers.
While the different clans of vampires were distinct in The Elder Scrolls III: Morrowind, even imbuing different strengths depending on your clan, there is no mechanic to support the same behavior in TES: Oblivion. As such, this question is never answered in-game and you are free to determine why Vicente does not make further mention of his (assumed) clan lineage.
That being said, he has a unique weakness to Garlic. Discreetly placing it in his inventory causes significant debuffs to his character. There is no such item in TES: Morrowind so it's never mentioned in that game. If you so choose, you can attribute this weakness to his Morrowind clan lineage rather than Cyrodiilic brethren - vampires who do not suffer this flaw.