Comparative morphology between the white grubs Pseudosymmachia tumidifrons and Brahmina faldermanni (Coleoptera: Scarabaeidae: Melolonthinae) using scanning electron microscopy

Abstract

Melolonthinae are the largest group of scarab beetles, causing destructive damage to human economy for the larvae attacking a wide variety of crops, pastures and turfs. Rhizotrogina are one of the most specious groups, with their larval taxonomy far from satisfactory. In this study, the larvae of Pseudosymmachia tumidifrons and Brahmina faldermanni were studied through rearing and direct observations using light and scanning electron microscopy. The larvae share the following morphological characters: three pairs clypeal setae, six minute sensilla on haptomerum, and absence of any stridulatory structures on mandibles. The larvae also exhibit distinct morphological differences, such as the number of heli, presence or absence of proplegmatia, size arrangement of spiracles, and the arrangement of palidia on raster. The dramatically morphological differences between these two closely related genera indicate the heterogeneity of the subtribe Rhizotrogina. The morphological and functional diversity of raster were briefly discussed.