Larval morphology of Panorpodes kuandianensis (Insecta, Mecoptera, Panorpodidae) and its evolutionary implications

Larval characters play a significant role in evolutionary and systematic studies of holometabolous insects. However, Panorpodidae, a derived family of Mecoptera, are largely unknown in their immature stages to date. Here, the first instar larva of the short-faced scorpionfly Panorpodes kuandianensis Zhong, Zhang & Hua, 2011 is described and illustrated using light and scanning electron microscopy. The larva of Panorpodes is remarkable for the absence of compound eyes on the head and the presence of seven small unpaired proleg-like processes along the midventral line on abdominal segments II-VIII. The homology of these unpaired appendage-like processes, their ecological adaptation, and the evolutionary implications of some larval characters of Panorpodidae are discussed.