Adaptations of immature stages of Sphaeridiinae (Staphyliniformia, Hydrophiloidea: Hydrophilidae) and state of knowledge of preimaginal Hydrophilidae

Several evolutionary trends of sphaeridiine beetles are discussed: terrestrial habits, larval developmental time, number of eggs/egg case, shape of the egg cases, prey consumption, construction of pupal chambers, reduction of the legs, development of hypopharyngeal lobes, symmetry of mandibles and labroclypeus, reduction of the ligula and fusion of stemmata. A discussion on the state of knowledge of the immature stages of Hydrophilidae at a generic level is presented; of the four most diverse zoogeographic areas, the Oriental, Australian and Ethiopian are the less known and the Neotropical is relatively well known; the Palaearctic and Nearctic are the least diverse but the best known.