Mormolyce phyllodes Hagenbach, 1825
Widespread and locally common in surviving rainforests of Southeast Asia, especially in Java, Indonesia, Brunei, Malaysia, Sumatra, Thailand and Papua New Guinea, this species is generally well known as an ornament; specimens are sold mounted in picture frames etc., and are available worldwide via the internet. Such ornamentals are obviously very popular and beyond this unmounted specimens are always available inexpensively at insect exhibitions and there are usually plenty of them. This is the most widespread member of the genus which includes seven species; all occur in Indonesia and four are endemic to that country, two further species also occur in Malaysia. The present species occurs as three regional subspecies; M. p. borneensis Gestro, 1875 from Borneo, Brunei, Indonesia and Malaysia, M. p. engeli Leiftinck & Wiebes, 1968 from Indonesia, and the nominate subspecies which is widespread. The common name relates to the general habitus but the hugely developed elytra render the beetles cryptic as they search for prey among cracks in the soil, leaf-litter, foliage or bark, and the greatly elongate forebody and antennae facilitates detecting and capturing prey. The main predators of violin beetles are birds and bats, less so terrestrial mammals. Both adults and larvae are predatory and both secrete a defensive fluid based on Butyric acid. Adults are active from August until November, they are mostly crepuscular and nocturnal and can fly over long distances, although they cannot fly from the ground and need to climb up trunks to do so, they are strongly attracted to arboreal fungi and readily come to artificial lights. Eggs are laid in sporocarps (species of Fomes have been recorded) and larvae develop over about nine months in an internal chamber, they pupate within and this stage lasts between two and three months, and the resulting adults chew their way out.
Adults reach 60-100 mm in length and this, coupled with the general habitus will identify the species as there is nothing remotely similar, but there are some points of interest. The antennae are slender and very long, and while the basal segment is thickened and scape-like, the second segment is diminutive. The narrow head has greatly elongated temples, convex and prominent eyes and relatively tiny palps and mandibles. The pronotum is strongly toothed laterally and sculpted dorsally. The elytra are hugely expanded, translucent and textured as to resemble a leaf, and despite extending well beyond the abdomen they are shaped in such a way as to leave the apical abdominal segment exposed from above. Beyond being slender and very long, the legs are typically carabid in form; the femora and tibiae are unmodified and the front tibiae are notched. There are no tibial bristles or obvious terminal spurs. The tarsi are five-segmented, slender and unmodified and, compared with the long legs, they are relatively short. There are no reliable sexual characters and while the antennae may sometimes by longer in males this has been shown to vary.