Description of the larva of Cybister (Melanectes) brevis Aubé, 1838 (Coleoptera, Dytiscidae, Cybistrinae)

Cybister (Melanectes) brevis Aubé, 1838 is an endangered species in Japan. Here, we present the first description of C. (M.) brevis larvae, emphasizing the chaetotaxy of the cephalic capsule, head appendages, legs, last abdominal segment, and urogomphi. Morphological differences between the subgenera Cybister Curtis, 1827 and Melanectes Brinck, 1945 include (1) the width of notches between medial and lateral projections of frontoclypeus, (2) the shape of egg bursters, and (3) the appearance of the clypeal lamellae.