Habitus of representative species of the three most diverse aquatic beetle families from Volcán Tacaná, Chiapas, Mexico A Elmoparnus pandus Spangler & Perkins, 1977 (Dryopidae) B Helichus suturalis LeConte, 1852 (Dryopidae) C Copelatus distinctus Aubé, 1838 (Dytiscidae) D Platambus americanus (Aubé, 1838) (Dytiscidae) E Cylloepus atys Hinton, 1946 (Elmidae) F Hexacylloepus metapa Silva-Polizei, Barclay & Bispo, 2020 (Elmidae) G Macrelmis leonilae Spangler & Santiago-Fragoso, 1986 (Elmidae) H Microcylloepus Troilus Hinton, 1940 (Elmidae) I Onychelmis longicollis (Sharp, 1882) (Elmidae).