The Blue-headed Pionus, Pionus menstruus: its Latin name refers to its red vent although all other Pionus parrots also have red vents.
Like all Pionus parrots, it comes from Latin America -- the Blue-headed native to southern Central America through to Brazil and Bolivia.
Reichenow's Blue-headed Pionus, Pionus menstruus reichenowii, is a subspecies of the Blue-headed above, but sometimes treated as a separate species.
The blue colour is less bright and extends to the chest and belly (instead of green). It is native to eastern coastal forests of Brazil.
Plum-crowned Pionus, Pionus tumultuosus, also called Speckle-faced Pionus (together with the White-headed Pionus below) is native to north-western South America.
White-headed Pionus, Pionus (tumultuosus) seniloides, is also called Speckle-faced Pionus (together with the Plum-crowned Pionus above).
White-capped Pionus, Pionus senilis, also called White-crowned Pionus, is native to Central America. As in all Pionus, male and female have similar plumage.
Coral-billed Pionus, Pionus sordidus, also called Red-billed, comes from the north and northwest of South America.
The Dusky Pionus, Pionus fuscus, also called the Dusky Parrot, is native to the north-eastern corner of South America.