For National summons, how about some demonic lions?
They might come in pairs...
http://en.wikipedia.org/wiki/Lions_of_Tsavo
Or, if you want to stick to West African lore, you could add the following:
Obia, a monstrous animal summoned to serve witches, also the name of the witches, themselves,
Sasabonsam, a vampire with iron teeth and iron hooks in place of hands, and on their feet,
Zin, water spirits that live in the Niger river.