The Great Mormon (Papilio memnon anceus) is a striking mainland Asian form of this highly variable swallowtail butterfly. Males, like the specimen collected on August 30, 1997, from Belitung Island, Indonesia, are deep black with a velvety sheen and subtle blue iridescence. They lack tails on their hindwings, distinguishing them from many other swallowtails. Females, in contrast, exhibit a range of mimicry patterns, often imitating toxic butterflies for protection.

Thriving in tropical forests and gardens, anceus caterpillars feed on citrus plants before maturing into their large-winged adult form. Their adaptability and strong flight make them successful pollinators. The anceus form, found across mainland Asia and nearby islands, represents the classic Great Mormon, displaying less variation compared to its island counterpart, merapu.