Review of the Hemiosus Sharp and Derallus Sharp of North America, Central America, and the Caribbean (Coleoptera: Hydrophilidae: Berosini) Short, Andrew Edward Z. Torres, Phillip J. Zootaxa 2006 1369 1 17 Sharp Sharp [400,588,1804,1830] Insecta Hydrophilidae Derallus Animalia Coleoptera 8 9 Arthropoda genus     1Metaventrite with median carina relatively fine and narrow (e.g. Fig. 10). Mesosternal process forming a bifid or toothed tubercle, but never a single broad pillar. Punctation on pronotum and elytra distinct..................................................................................... 2 - Metaventrite with the median carina very broad ( Fig. 11). Mesosternal process forming a robust, posteriorly curved pillar. Punctation on pronotum and elytra extremely fine ( Fig. 9) ......................................................................................... D. angustusSharp    2Interstria X with a single row of fine punctures, or at most an irregular double row (e.g. Figs. 6–7). Aedeagus normal, without extension of basal piece; parameres may be blunt but never quadrate ........................................................................................... 3  - Interstria X with a broad field of punctures, usually three across on anterior half ( Fig. 8). Aedeagus with basal piece greatly extended, with apical portion of parameres bluntly quadrate ........................................................................................ D. rudisSharp    3Mesosternal process with posterior tooth distinctly more elevated than anterior tooth, the latter sometimes appearing nearly absent................................................................ 4  - Mesosternal process with two apical teeth more or less coplanar.....  D. altus(LeConte)    4Ground punctation between intervals fine but distinct ( Fig. 7) .... D. terraenovaeOliva  - Ground punctation between intervals present but nearly obsolete.................................. ................................................................................................. D. ambitusd’Orchymont