Did you reach under the fuel rail and feel the whole way along the underside? The connector would not be visible from above.Thanks, I had a look but there is not a female plug that I can see.
The car appears to be running ok, it's just frustrating.
Oh and the connector you photographed seems to be female, so itshould be easy to feel the pins on the underside of the fuel rail (if it is the same).
A quick google returned the attached image and the info that the connector I spotted is for the fuel rail pressure sensor (which has the same pin configuration as your connector.