بررسی دوشکلی جنسی در شکل و اندازه بال شب‌پره‌های Catocala abacta (Lepidoptera, Erebidae) و Catocala brandti

Sexual dimorphism is an especially common form of intraspecific variation in the Lepidoptera. If the sexes differ in the opportunity for selection in body size, dimorphic evolution leads to differences in the adult body size between males and females in a population which is mentioned as sexual size dimorphism. In Iran, moths of Catocala abacta Staudinger, 1900 and Catocala brandti Hacker & Kautt, 1999 mostly occur in Zagros forests. In this research, sexual wing dimorphism of the two species were studied by geometric morphometrics. Required specimens were collected by light trap from Malaqa in Khuzestan province (31°36'30''N 49°59'50''E) during May 2017. In order to investigate sexual dimorphism in shape and size of wings, forewings of 29 males and 32 females in C. abacta and 28 males and 29 females in C. brandti as well as hindwings of 29 males and 31 females in C. abacta and 30 males and 30 females in C. brandti were photographed after removing scales. We digitized 19 landmarks in forewings and 14 landmarks in hindwings to capture configuration of shape and size, using tpsDig software. Thirty four shape variables in forewings and twenty four in hindwings were obtained through relative warps analysis by tpsRelw and limits of shape variation were determined for males and females of the two species. The first 10 shape variables which were explained more than 90% of the variation in shape of each wings, were selected for multivariate analysis of variance (Manova). Results showed that shape of forewings in C. abacta (wilks' λ= 0.165, F(10,50) = 25.23, P<0.0001) and C. brandti (wilks' λ= 0.259, F(10,46) = 13.137, P<0.0001) were significantly different between males and females. Shape of hindwings in C. abacta (wilks' λ= 0.501, F(10,49) = 4.89, P<0.0001) and C. brandti (wilks' λ= 0.326, F(10,49) = 10.15, P<0.0001) were significantly different between males and females, too. Forewings were better separated males and females than hindwings. In forewings, difference between sexes is due to more elongated anterior part of wings in males. Calculation of centroid size of wings indicated that it was smaller in males than females for fore- and hindwings in C. abacta whereas centroid size of females was smaller than males for forewing in C. brandti. Centroid size was not significantly different between males and females in hindwings of C. brandti.