Hydraenidae of Madagascar (Insecta: Coleoptera) Author Perkins, Philip D. text Zootaxa 2017 2017-11-03 4342 1 1 264 journal article 31639 10.11646/zootaxa.4342.1.1 15799d2a-1968-4874-8100-452597d4e26b 1175-5326 1041066 2ACD54D2-3487-432D-9323-EEC131FE2E64 Hydraena Kugelann, 1794 Hydraena Kugelann, 1794: 578 (type species Hydraena riparia Kugelann 1794: 579 ). The hyperdiverse, cosmopolitan genus Hydraena is well defined by the following autapomorphic morphological characteristics: 1) presence of a labral-mandibular interlocking device ( Perkins 1989 ), 2) mentum with an acute median projection anteriorly ( Perkins 1989 ), 3) various complex sensilla ( Perkins 1997 ), and 4) specialized features of the exocrine secretion delivery system ( Perkins 1997 ). There is general agreement among current workers that Hydraena is monophyletic, based on these morphological characters (for example, Jäch et al. 2000).