Bidirectional sex change in the magenta dottyback Pictichromis porphyrea: first evidence from the field in Pseudochromidae

Abstract

Protogyny and protandry are well known among fishes, but bidirectional sex change has been reported from only 25 species in six families; field evidence is limited to nine species in four families. The present study confirmed bidirectional sex change of the magenta dottyback Pictichromis porphyrea in the field, the first field evidence for this phenomenon in the family Pseudochromidae. Field experiments were conducted on the patch reefs of Sesoko Island, Okinawa. The sex ratio was female-biased, and males were significantly larger than females. These features are common to protogynous species with a polygynous mating system, although mating behavior was not observed. When members of the opposite sex were removed from a certain area, nearly half of the tagged fish moved to different sites. Among the fish that moved from the original site, four females changed to male, and two males changed to female. Gamete release was confirmed both before and after the sex change. The sex-changed males were larger than their neighbors, whereas the sex-changed females were smaller than their neighbors, suggesting that the sex change was socially controlled in both directions.