Abstract
Scale characteristics and its detailed structure from different body regions were studied in three Plectorhynchus species in terms of morphometry and Scanning Electron Microscopic techniques. The present work has been suggested to the rarity of taxonomic and biological information about the three Plectorhynchus species, P. gaterinus, P. pictus and P. schotaf from the Red Sea. A wide spectrum of size-free intraspecific and interspecific variations was recorded and documented concerning the overall form of the scales and their morphometrics, scale surface morphology, the primary, secondary and tertiary radii counts, shape of interradial tongues and the first circuli, the interradial circuli, most outer lateral circuli, inner lateral circuli, denticles on circuli, interradial and intercircular grooves, segmentation and granulation pattern of the caudal field and the shape of ctenii. The quantitative scale characters of Plectorhynchus species are subjected to cluster analysis that revealed two main subclusters, the first includes P. gaterinus and P. schotaf, and the second subcluster includes P. pictus. In addition to the intraspecific variations, the highly significant interspecific variations in the morphometric indices also were evident from one body region to another (P<0.01). The pattern of variations reflected by CVA referred to the partial discrimination between the three Plectorhynchus species considered. Among the scale characteristics used to differentiate between Plectorhynchus species are the overall shape of the lateral line canal, the relative position of its anterior and posterior openings and the cantilevered anterior extension of the canal. [Ahmed S. A. Harabawy, Imam A. A. Mekkawy and Ali Alkaladi. Identification of three fish species of genus Plectorhynchus from the Red Sea by their scale characteristics. Life Sci J 2012; 9(4): 4472-4485]. (ISSN: 1097-8135). http://www.lifesciencesite.com. 673