Discovery of Dichocrocisfrenatalis Lederer, 1863 (Lepidoptera, Crambidae, Spilomelinae) in mangrove environments of the Ryukyu Islands, Japan, and tribal placement of the genus.

Dichocrocisfrenatalis Lederer, 1863, the little-known type species of the polyphyletic genus Dichocrocis, was discovered in the Ryukyu Islands, Japan. We provide a redescription of the adult morphology, including the male genitalia with highly developed hair-pencil structures, as well as female genitalia. The phylogenetic placement of this genus, and therefore its type species, within Spilomelinae has been uncertain, but our molecular phylogenetic analysis and morphological evaluation support the placement of the genus Dichocrocis in the tribe Steniini. Additionally, as a novel ecological observation, we report that the Japanese population of this species is abundant in mangrove environments, where the adults frequently aggregate on the underside of leaves and are preyed upon by a mangrove-associated robber fly.