Sexual dimorphism and allometric relationships in the wings of two underwing moths (Lep., Erebidae, Catocala)

Abstract

Sexual dimorphism has been observed in various Lepidoptera species, with the majority exhibiting female-biased sexual size dimorphism. As the first geometric morphometric study on Catocala wings, we sought to determine the sexual dimorphism in the wing size and shape of Catocala abacta and C. brandti, as two sympatric congeneric species, and their associated allometric patterns. These two species frequently coexist in western Iran's oak forests. On the fore- and hindwings of males and females of the studied species captured in southwest Iran, 19 and 14 landmarks were digitized, respectively. The patterns of variation in the shape of wings were investigated using relative warp analysis. The results indicated an apparent sexual dimorphism in the shape of the forewings but not the shape of the hindwings. Females of C. abacta had larger centroid sizes than males, whereas males of C. brandti had larger centroid sizes than females in both wings. Additionally, we observed a distinct allometric pattern on both species' fore- and hindwings. Our finding corroborates previous research demonstrating sexual dimorphism in the wings of Lepidoptera as a proxy character, implying that selection may affect wing shape to improve flight behavior and efficiency.