Cotorra cabeciazul (AR)

Recent analyses suggest this species requires separate genus, for which name Thectocercus is available. N forms koenigi, neoxenus and haemorrhous are distinct from S forms acuticaudatus and neumanni in their flesh-coloured vs black lower mandible (3); reduced blue on crown and face (1 in comparison with neumanni); and smaller size, not in bill (which may be bigger) but mainly in tail length (effect size −1.87; score 1); more research needed to evaluate taxonomic status. Date of original publication of race koenigi disputed; this and use of the apparently synonymous nigrirostris (of the same author) require clarification.

Five subspecies recognized:

• P. a. koenigi (Arndt, 1990) – N & E Colombia and N Venezuela (E to Monagas).
• P. a. neoxenus (Cory, 1909) – I Margarita (Venezuela).
• P. a. haemorrhous (Spix, 1824) – Northern Blue-crowned Parakeet – interior NE Brazil (S Piauí, N Bahia, Pernambuco, Alagoas, N Minas Gerais).
• P. a. neumanni (Blake & Traylor, 1947) – upland E Bolivia (Cochabamba, W Santa Cruz, Chuquisaca, and perhaps Tarija).
• P. a. acuticaudatus (Vieillot, 1818) – Southern Blue-crowned Parakeet – lowlands of E Bolivia, Paraguay and SW Brazil to N Argentina (S to E La Pampa and W Buenos Aires); probably extinct in Uruguay.

33–38 cm; 170–176 g. Head dull blue, bare orbital ring white; body and wings green, paler below, sometimes with blue tinge on breast; tail old gold below with reddish inner webs basally, green above with outer feathers brownish red and tipped dark yellow-green. Immature has reduced blue on head. Race neumanni has forehead to nape blue, rest of head green, underparts washed blue; haemorrhous has only forecrown blue, no bluish wash below, and lower mandible horn-coloured; koenigi like haemorrhous but much smaller, with less red to inner webs of undersides of tail; neoxena same size as koenigi but breast and abdomen bluish green.