In the April 2017 British Birds, there is an article by Guillermo Rodriguez, Juan Ramirez and Javier Elorriaga entitled 'Phenotypic characteristics of Common Buzzards on Fuerteventura'; the abstract says
"The Common Buzzards Buteo buteo ‘lanzarotae’ from Fuerteventura, in the Canary Islands, are distinctive. This taxon often resembles Long-legged Buzzard B. rufinus but also shows some plumage traits consistent with Common Buzzard B. buteo. We describe the plumage of ‘lanzarotae’, and highlight features that separate it from Common Buzzards in the western Canary Islands and from North African Long-legged Buzzard B. r. cirtensis. We suggest that the appearance of ‘lanzarotae’ may be the product of a hybrid origin and also that currently accepted records of Long-legged Buzzard in the Canary Islands are in fact ‘lanzarotae’."
N.b. IOC v9.2 does not recognise 'lanzarotae' but also does not include any part of the Canaries as part of the range of 'cirtensis' either.