Possible link between the structure of otoliths and amphibious mode of life of three mudskipper species (Teleostei: Gobioidei) from the Persian Gulf

The otoliths of three mudskipper species from the Persian Gulf that are characterised by different degrees of amphibious adaptation were examined using SEM imaging and otolith morphometry. Scartelaos tenuis, which is the most aquatic of the three species, has rhomboid to rectangular otoliths that conform to the general otolith type of many marine gobiid species. The otoliths of Periophthalmus waltoni, which is one of the most amphibious mudskipper species, are pentagonal-shaped and deviate from the usual otolith type of the Gobiidae by the absence of a posterodorsal projection and deep ostial lobes. Boleophthalmus dussumieri is intermediate with respect to its amphibious adaptation between S. tenuis and P. waltoni, and the shape of its otoliths is intermediate between the otoliths of those two species. Otolith morphometry related to sulcus measurements more clearly separated P. waltoni from B. dussumieri, than S. tenuis from either P. waltoni or B. dussumieri. As P. waltoni and B. dussumieri can occur syntopically and display similar behaviours, the morphometric disparity of their sulcus proportions might be related to efficient intraspecific communication among neighbouring species.