Figs. 18–28 in The Predaceous Diving Beetles (Coleoptera: Adephaga: Dytiscidae) from the Miradores Lagoon, Veracruz, Mexico

Figs. 18–28. Morphological structures of Dytiscidae. 18) Middle part of prosternum and prosternal process on the same plane (Laccophilinae, Copelatinae, Colymbetinae, Cybistrinae, Dytiscinae) (a: prosternal process); 19) Middle part of prosternum and prosternal process not on the same plane, prosternal process at a lower level (Hydroporinae) (a: prosternal process); 20) Apical half of median lobe of Celina slossoni; 21) Apical half of the median lobe of Celina angustata; 22) Metanepisternum (a) reaching mesocoxal cavity; 23) Metanepisternum (a) not reaching mesocoxal cavity; 24) Metacoxal processes apically broad and trilobite in Hydrovatini (a: lateral lobes; b: middle lobe); 25–26) Parameres in lateral and dorsal view of Hydrovatus youngi; 27–28) Parameres in lateral and dorsal view of Hydrovatus davidis. Figs. 18, 19, 22–24 taken from Arce-PÉrez and Roughley (1999); Figs. 20, 21 from Young (1979); Figs. 25–28 from Biström (1996).