Stenus heterocerus, L. Benick, 1929

Mainda, Tobias, 2020, Stenus praedator sp. nov. from the Philippines and a new species group in Stenus Latreille, 1797 (Coleoptera: Staphylinidae, Steninae), Zootaxa 4759 (3), pp. 405-412 : 410-411

Key to the species of the S. heterocerus group

1 Pronotum moderately finely and sparsely punctured (Figs 13, 16)............................................... 2

- Pronotum coarsely and densely punctured (Figs 14, 15, 17, 18)................................................. 3

2 Elytral punctation sparser and less coarse ( Fig. 4 ). Aedeagus ( Fig. 9 ). 6.6 mm. Negros................ S. inflaticollis Puthz

- Elytral punctation denser and coarser ( Fig. 1 ). Pronotum (Fig. 13). Aedeagus unknown. 6.5–7.0 mm. Samar .............................................................................................. S. heterocerus L. Benick

3 Pronotum without impunctate areas (Fig. 14). Abdominal segments posteriorly enlarged. ♂: metafemur with node-shaped dila- tion in basal third ( Fig. 2 ); aedeagus ( Fig. 11 ). ♀: legs unmodified. 6.0– 7.5 mm. Mindanao......... S. thaumatocerus Puthz

- Pronotum with some impunctate shiny areas................................................................ 4

4 Interstices of pronotum and elytra wider. Body with Prussian blue hue. ♂: parameres not extending beyond apex of median lobe ( Fig. 8 ). 6.5–7.5 mm: Leyte ............................................................ S. ernstjuengeri Puthz

- Interstices of pronotum and elytra narrower. Body black. ♂: parameres extending beyond apex of median lobe........... 5

5 Punctation of frons less sparse ( Fig. 3 ). ♂: apical portion of median lobe longer and less broad ( Fig. 7 ). 7.4 mm. Mindanao..................................................................................... S. praedator sp. nov.

- Punctation of frons sparser ( Fig. 6 ). ♂: apical portion of median lobe shorter and broader. 7.5 mm. Mindanao..................................................................................................... S. quatei Puthz

Figures

FIGURES 4–6. Holotypes of S. inflaticollis (photo: Field Museum of Natural History 2019) (4), S. ernstjuengeri (photo: Museum of Comparative Science 2019) (5) and S. praedator sp. nov. (6).

FIGURES 7–9. Aedeagi of S. praedator sp. nov. (7), S. ernstjuengeri (8) and S. inflaticollis, holotype, from Puthz (1998) (9).

FIGURES 1–3. Holotypes of S. heterocerus (photo: Field Museum of Natural History 2019) (1), S. thaumatocerus (photo: Field Museum of Natural History 2019) (2), S. quatei (photo: Bishop Museum, James Boone 2019) (3).

FIGURES 10–12. Aedeagi of S. quatei, holotype, from Puthz (2013) (10), S. thaumatocerus, holotype, from Puthz (1974) (11) and antennomere X of S. thaumatocerus, holotype (12).