Derallus Sharp

Short, Andrew Edward Z. & Torres, Phillip J., 2006, Review of the Hemiosus Sharp and Derallus Sharp of North America, Central America, and the Caribbean (Coleoptera: Hydrophilidae: Berosini), Zootaxa 1369, pp. 1-17 : 9-10

Key to the Derallus Sharp exclusive of South America

1 Metaventrite 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. angustus Sharp

2 Interstria 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. rudis Sharp

3 Mesosternal 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)

4 Ground punctation between intervals fine but distinct ( Fig. 7 ) .... D. terraenovae Oliva

- Ground punctation between intervals present but nearly obsolete.................................. ................................................................................................. D. ambitus d’Orchymont

Figures

FIGURES 10 – 11. Ventral view of the metasternum of Derallus. 10: D. rudis Sharp; 11: D. angustus Sharp. Scale bar 0.2 mm.

FIGURES 6 – 9. Lateral view of left elytron of Derallus. Arrows indicate the tenth elytral interstria. 6: D. altus (LeConte); 7: D. terraenovae Oliva; 8: D. rudis Sharp; 9: D. angustus Sharp. Scale bars 1.0 mm.