It means of external origin, alien to the race or family. Strange , alien . Originated in another place or in another family or descent. There is also the word hectogeneo in Spanish, thus with h, and means that it has five components of matter but mixed in unequal proportions.
It may be an error by ectogen. See ecto- ("out" ), endogenous , exogenous , . . .
ECTO ECTOGENEO- prefix of the Greek , external , which is outside , and gene , race , birth , descent , generation; that is created externally