Dark mom is an anagram of Mod Mark.
Slann are lizardmen in Warhammer. Slans could be the never released lizardmen. It should be noted Mod Mark always wanted to release them, but never has yet.
Carthaginian could refer to Hannibus, one of the never released Dragon Riders. Hannibal was the leader of the famous Carthiginian army, that tried to invade Rome.
With the latest podcasts, and the information regarding the future release of Dragon Riders, it could very well mean the unreleased lizardmen are finally coming to the game:
"Mod Mark will be happy to hear that his Lizardmen are Runescape's Dragon Riders."