Xylocopa pubescens strongly resembles Xylocopa aestuans, but the latter is found in Africa, the Middle-East and parts of Asia.
Originally, Xylocopa pubescens is found throughout the Eastern Mediterranean Basin, North Africa and the Middle East.
Until recently, Xylocopa pubescens was not known in Europe, but it seems that since 2015 it expanded its distribution to Spain and Greece in Europe.
As a result, it is very likely that my photo shows Xylocopa pubescens.
Research has proved that this would mean that my sighting may be the firsting sighting of Xylocopa pubescens in Europe.
I am awaiting further confirmation.

Lavrion, Greece, 28 September 2012