Are Hoovooloo's members of a species?

Since matter is the principle of individuation (not of individuality but of individuation), do Hoovooloos have what it takes to be individuals within a species, like men, or must we say that each hoovooloo, like each angel, is his own species?
Consider, the essence of a hoovooloo is to be a hyperintelligent pan-dymensional shade of the colour blue.
Would a particular hoovooloo be identical this essence, or does it have anything belonging to itself so as to set it apart from its essense? There is no matter in its definition. But there is an accident the definition (shade of the colour blue). So, are hoovooloos like angels or like men? What do you, my fellow Douglas Adams fans, think?