カブトムシ幼虫の雌雄は糞でも判る

C. Takai-Yamashita, S. Yamashita, Y. Mabuchi, A. Teramae, T. Matsuyama, Y. Taguchi, T. Mushika, Y. Wada, S. F. Novasari, J. Ikeda, Y. Ohya (2022) Sex determination of Japanese rhinoceros beetles, Trypoxylus dichotomus (Coleoptera: Scarabaeidae), based on their dropping shape. Advanced Powder Technology, 33(5): 103552. https://doi.org/10.1016/j.apt.2022.103552.

projected area/Feret diameter (A/F)を見れば雌雄が判別できるとのことで面白い。が、projected areaが具体的にどこなのかがちょっと判らなかった。