FIGURES 11 – 26 in Taxonomic revision of New World species of the genus Oosternum Sharp (Coleoptera: Hydrophilidae: Sphaeridiinae) I. Definition of species groups and revision of the Oosternum aequinoctiale group

FIGURES 11 – 26. Characters for distinguishing species groups of the genus Oosternum (see Table 1 for details). 11 – 12, 23: O. sculptum group; 13 – 14: O. group C; 15 – 16, 19, 26: O. aequinoctiale group; 17: O. soricoides group; 18, 21: O. sahlbergi group; 20, 25: O. attacomis group; 22, 24: O. group A