The line of contact between G. p. palpalis and G. f. quanzensis passes near Brazzaville, at the south and southwest of the Congolese capital. Observations made between 1948 and 1961 show the advance of G. p. palpalis towards Brazzaville, along the Djoué Valley and the Congo River. Recent captures confirm this spectacular advance of G. p. palpalis to the detriment of G. f. quanzensis along the Djoué Valley. Indeed, G. f. quanzensis is no longer found in a distance of 20 km where it used to co-exist with G. p. palpalis. Ecological competition for food or habitat thus occurs between these two closely related species. It is suggested that both heterospecific copulations and demographic pressure play a crucial part in the exclusion.
