Larval structures and bionomics of Semijulistus spectabilis (Coleoptera: Rhadalidae)

Abstract: Morphology of mature larvae and life cycle of Semijulistus spectabilis (Lewis, 1895) (Coleoptera: Rhadalidae) are described here for the first time. A comparative analysis of the larval morphology of S. spectabilis and other rhadalid species revealed that the larvae of S. spectabilis lacked the typical characteristics observed in other rhadalid species, i.e., pigmented and sclerotized (whole or partial) thoracic tergites, abdominal tergite IX bearing a pair of urogomphi or a pigmented sclerite. Furthermore, S. spectabilis exhibits distinctive characteristics that deviate markedly from the fundamental larval morphology typical of the melyrid lineage, including a small head capsule, a slender body, and an exceptionally thin cuticle. Although the total duration of the larval stage was long, there were fewer larval molts until they prepupated than observed in other members of the melyrid lineage.

Key words: Coleoptera, Cleroidea, Rhadalidae, developmental period, larva, morphology, voltinism, Japan, Palaearctic Region