Not physically. The implication is that, since the Asari are all innately psychic, they use their mind powers to manipulate how they are percieved by other species. Like Grant_us_eyes said, this is all based on one encounter with NPCs having a conversation about an Asari dancer where each of them, being members of a different species, all said the Asari look more like them than any other. It's not a complete illusion, the Salarian still asked what 'that pit in her stomach' was, and the human said it was her naval. So they still present themselves as mammalian regardless of species.