Morphology of the egg-case and larva of Paracymus aeneus (Germar) (Coleoptera: Hydrophilidae)

The generic and species identity of previously described larva of Paracymus aeneus (Germar, 1824), the type species of the genus Paracymus Thomson, 1867, has been a subject of controversy owing to their morphological similarity to the genus Anacaena Thomson, 1859. In this study, we describe morphology of the egg-case and all three instar larvae of P. aeneus based on Japanese specimens obtained through rearing and provide the biological information on the species under rearing conditions. The morphology of the larvae corresponds with that of known Paracymus larvae rather than Anacaena. Consequently, larvae previously described as P. aeneus do not belong this species. Therefore, this is the first description of the immature stages of P. aeneus.