Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3.

The Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae) has been recently diagnosed and artificially subdivided into three sections based on the morphology of the female subgenital plate. In the present study, the species in the third and final section, characterized by the posterior margin of the subgenital plate with the central lobe and posterolateral corners almost at the same level, are revised.

The group includes 13 species: nine from Mexico (Ambrysus altiplanus Reynoso, A. colimanus Polhemus & Polhemus, A. hydor La Rivers, A. inecol Reynoso, A. magniceps La Rivers, A. quadracies La Rivers, A. scalenus La Rivers, A. signoreti Stål, A. sonorensis Usinger), one from Belize (A. cayo Sites & Shepard), one from El Salvador, Guatemala, Honduras, and Mexico (A. dyticus La Rivers), one from Guatemala and Mexico (A. sitesi Reynoso), and one from Mexico and the United States (A. occidentalis La Rivers).

Supplemental descriptions are provided for eight species for which important features of the last abdominal segments of the male and female were unknown or poorly known. Also, A. portheo La Rivers and A. rotundus La Rivers are proposed as junior synonyms of A. signoreti. These changes bring the total number of species in the complex to 23, in the nominotypical subgenus to 59 species, and in Ambrysus Stål to 67.

Furthermore, new state records from Mexico are presented for A. hydor, A. magniceps, and A. occidentalis, in addition to a compilatory checklist of the species in the genus Ambrysus. Also, we provide an illustrated key to the species complexes in the subgenus Ambrysus Stål, the sections in the A. signoreti complex, and the species in its Section 3. This work represents our final major contribution to clarify the taxonomy of species in the North American genus Ambrysus.