International Academy of Ecology and Environmental Sciences Proceedings of the International Academy of Ecology and Environmental Sciences 2220-8860 14 3 2024 9 1 Elytron shape variability among selected synanthropic beetles from Southern Philippines 86-94 EN Ernel D. Bagbag Cesar G. Demayo Mark Anthony J. Torres http://www.iaees.org/publications/journals/piaees/articles/2024-14(3)/shape-variability-among-selected-synanthropic-beetles.pdf> The shape of biological structures is frequently studied using qualitative features, although this methodology can produce ambiguities and score mistakes. In addition, the lack of homologous locations and the challenges in comparing linear measurements limit the ability of standard morphometrics to quantify shape. Geometric Morphometrics (GM) is an alternate method for examining an organism's shape that addresses the shortcomings of conventional morphometrics and qualitative features. This study used GM to investigate the phenetic relationships of selected synanthropic Coleopteran species based on the shape of their elytron, which is an autapomorphic trait of beetles. Using Principal Component Analysis (PCA), it was possible to see how the average shape of these structures changed over time, and the results showed considerable shape differences between species. The sampled elytra displayed a broad shape with outward displacement on the anterior part, and a concave shape with a displacement on the mid-lateral section (PC1 = 84%, PC2 = 6.79%). These structures represent adaptations seen in Coleopteran species, which offer insightful information about the morphological evolution of elytron and to understand diversification of beetles.