Morphological and molecular analyses unveil phenotypic polymorphism in hairy maggots of the genus <i>Chrysomya</i>

Some species of the genus Chrysomya, known as hairy maggot blowflies (Diptera: Calliphoridae), are medically and forensically important insects worldwide. However, identifying these species can be challenging due to morphological characteristics overlapping. In this study, we investigated morphological and molecular differences among three hairy maggot blowflies: Chrysomya rufifacies Macquart, 1843, Chrysomya albiceps (Wiedemann, 1819), which are widely distributed throughout the Old World, respectively; and Chrysomya villeneuvi Patton, 1922, which is restricted to Asia. Morphological analysis revealed overlapping characters in larval and adult stages of C. rufifacies and C. albiceps based on traditional diagnostic characters, confirming phenotypic polymorphism in both species. Due to the global spread of these species, likely by human activity and climate change, a morphological and phylogenetic investigation was underway. A revision of the established morphological keys was proposed, and the phylogenetic analysis supported a sister relationship among the three species, with C. rufifacies more closely related to C. albiceps (genetic distances of 2.42%-3.13%) than to C. villeneuvi (3.49%-4.40%). Notably, C. albiceps differed from C. villeneuvi (3.31%-3.48%), suggesting that C. albiceps, occupies an intermediate evolutionary position between C. rufifacies and C. villeneuvi.