Evolution in action-peacock-feather like supraocular tentacles of the lionfish, Pterois volitans - the distribution of a new signal

Observations on populations of the lionfish, Pterois volitans (Scorpaenidae), in the Red Sea revealed that during the last four decades a novel phenotype of this species has started to evolve, which instead of the typical ray-like supraocular tentacles bears a pair of feather-like tentacles, one or both of which bear a sharply defined eye-mark, previously noted in this fish in the eastern Indian ocean. During the ongoing studies of the last 25 years it has become clear that this ornamentation, possibly first observed in the Red Sea at the southern tip of Sinai, had gradually extended both westward to the Egyptian shores, and eastward, along the 180 km of the Gulf of Aqaba. In the last decade such ornamented specimens have begun to appear and multiply at the northern tip of the Gulf, within the large population of 'regular' lionfish bearing ray-like tentacles. The evolutionary basis for this development, and the possible usefulness of this novel signal are discussed.