Skull shape variation in the Armored Sailfin catfish, Pterygoplichthys disjunctivus (Siluriformes: Loricariidae), described using geometric morphometrics

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Research Paper 01/09/2017
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Skull shape variation in the Armored Sailfin catfish, Pterygoplichthys disjunctivus (Siluriformes: Loricariidae), described using geometric morphometrics

Mark Anthony J. Torres, Jan Deo B. Moldez, Cordulo P. Ascaño
J. Bio. Env. Sci.11( 3), 73-80, September 2017.
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The two-dimensional shapes of the skulls of male and female Armored Sailfin Catfish, Pterygoplichthys disjunctivus, were reconstructed in this study using Thin-Plate Spline (TPS) grids. The rationale for doing this is to draw out hypotheses regarding the life history and population dynamics of the Armored Sailfin Fish, which is becoming a nuisance in some freshwater environs. Because of the skull’s rigid structure, it offered many stable landmark points that are compatible with geometric morphometric computations and modeling. Through Relative Warp Analysis of forty-nine homologous points, it was observed that the skulls in both sexes differ widely in the length-width aspect ratio (RWI: 38%). The skulls were also asymmetrical with regard to the anterior latero-ethmoidium side of the structure based on analyses of five other relative warps that had a cumulative variance of 38.29% (RW2 to RW6). Because these variations are localized around regions associated with feeding structures, it does not escape our minds that the fishes might differ in their individual feeding habits.


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