Ultramicroscopy of structures involved in the posterior region of scales in two flathead fishes (Teleostei: Perciformes)
Morphology of structures involved in the posterior region of scales in two flathead fish species viz. Platycephalus indicus and Grammoplites suppositus was studied using ultramicroscopy. The fish individuals were divided into three size groups based on their standard lengths and their scales were removed from four body regions. The microscopic observations indicated that the scales of both species were ctenoid. The posterior margin of all scales was formed by two rows of ctenii. Typically, the shape of the posterior region of scales in P. indicus was crescent, while it was triangular in G. suppositus. The number of ctenii in the scales of P. indicus was minimum 12 and maximum 60, while in G. suppositus it was minimum 6 and maximum 38. Moreover, the results indicated that the number of ctenii was increased during fish development because the smaller fishes have fewer ctenii in their scales than the adults, while, their general morphology has not been changed properly. This developmental change was significantly higher in P. indicus than G. suppositus. The increase of ctenii during fish development allows greater flexibility in movement. In conclusion, modification in the ornamentations of the posterior region has a hydrodynamic function and they are subject to modification during the fish development. The ctenii varying considerably in the number and could be easily counted, therefore, could be used as an appropriate taxonomic character at least in flathead fishes or even other fish groups.
Bräger Z., Moritz T. (2016). A scale atlas for common Mediterranean teleost fishes. Vertebrate Zoology, 66: 275-386.
Burdak V.D. (1969). Ontogenesis of squamation in the mullet (Mugil saliens Risso.). Zoologicheskii Zhurnal, 48: 241-247.
Burdak V.D. (1986). Morphologie fonctionnelle du tegument ecailleux des poissons. Cybium, 10: 147.
Fricke R., Eschmeyer W.N., Van der Laan R. (2020). Eschmeyers Catalog of Fishes: Genera, Species, References. last access in 08/08/2020. http:// researcharchive.alacademy.org/research/ichthyol ogy/catalog/fishcatmain.as.
Froese R., Pauly E. (2015). FishBase. World Wide Web electronic publication. www.fishbase.org.
Hughes D.R. (1981). Development and Organization of the posterior field of ctenoid scales in the Platycephalidae. Copeia, 3: 596-606.
Johnson G.D. (1984). Percoidei: development and relationships. In: H.G. Moser., Richards W.J., Cohen D.M., Fahay M.P., Kendall A.W., Jr. Richardson S.L. (Ed.), Ontogeny and systematics of fishes. American Society of Ichthyologists and Herpetologists No. I.
Imamura H. (1996). Phylogeny of the family Platycephalidae and related taxa (Pisces: Scorpaeniformes). Species Diversity, 1: 123-233.
Imamura H., McGrouther M. (2008). New records of a flathead fish, Onigocia grandisquama (Regan, 1908) (Teleostei: Platycephalidae) from Australia. Memoirs of the Queensland Museum, 2: 239-243.
Lippitsch E. (1990). Scale morphology and squamation pattern in cichlids (Teleostei, Perciformes): A comparative study. Journal of Fish Biology, 37: 265-291.
Mastrototaro F., Roberto C., Francesca C., Letizia S. (2007). First record of dwarf flathead Elates ransonnetii (Platycephalidae) in the Mediterranean Sea (North-Western Ionian Sea). Cybium, 31: 393-394.
Motamedi M., Teimori A., Amiri V., Askari Hesni M. (2020). Characterization of age-dependent variability in the flank scales of two scorpaeniformes fishes by applying light and scanning electron microscopy imaging. Micron. 128 p.
Roberts C.D. (1993). Comparative morphology of spined scales and their phylogenetic significance in the teleostei. Bulletin of Marine Science, 1: 60-113.
Sire J.Y. (1986). Ontogenetic development of surface ornamentation in the scale of Hemichromis bimaculatus (Cichlidae). Journal of Fish Biology, 28: 713-724.
Sire J.Y., Arnulf I. (2000). Structure and development of the cteniial spines on the scales of a teleost fish, the cichlid Cichlasoma nigrofasciatum. Acta Zoologica, 81: 139-158.
Takagi K. (1953). A study of the scale of the gobiid fishes of Japan. Journal of the Tokyo University of Fisheries, 39: 231-257.
Wonsettler A.L., Webb J.F. (1997). Morphology and development of the multiple lateral line canals on the trunk in two species of Hexagrammos (Scorpaeniformes: Hexagrammidae) Journal of Morphology, 233: 195-214.