Many thanks to Gary Stiles for directing me to his comments in the articles by Stiles,Roselli and Bohóhorquez,1999,Bulletin of the British Ornithologists' Club,119,no.2,on pp.120-21 for very valuable discussion of the place of race abbreviatus.  To see the results go to Ramphastos swainsonii and remember to click on Citations,Notes and Synonyms to look at the reasons.

Enjoy,

John Penhallurick