Genji firefly

The Genji firefly (Luciola cruciata, moved to the genus Nipponoluciola in 2022) is an aquatic lampyrid endemic to Honshu, Shikoku and Kyushu in Japan. Adults are sexually dimorphic: males measure 10.5–16.5 mm, females 15.0–18.6 mm, with black elytra and a pale pinkish-red pronotum, and males flash yellow-green while patrolling streams. Larvae live in clean, slow water and prey chiefly on freshwater snails for more than a year. Adults do not feed and live under three weeks. The IUCN has not assessed it; Japan treats it as an indicator insect for stream quality.