Chlaenius (Chlaeniostenus), 1919

Serrano, Artur R. M., 2024, Ground beetles of the tribes Chlaeniini Brullé, 1834 and Rhopalomelini Alluaud, 1930 (Carabidae: Licininae) of Guinea-Bissau: description of two new species and faunistic notes, Zootaxa 5397 (1), pp. 1-35 : 18

Key to the Chlaenius (Chlaeniostenus) species of Guinea-Bissau

An identification key for the Guinea-Bissau species is provided, including the new species. However, as the male genitalia are a fundamental diagnostic character, this key can be used only for male specimens. Chlaenius denticulatus denticulatus and C. helios are identified in any alternative dichotomic step 4, since both can present specimens within these options. After reaching the identification of a species, other characters can be added, to reinforce a positive diagnosis (e.g., pronotum and ventral characters/traits).

1. Elytra shiny black, without any yellow marginal band; under side blackish, abdominal sternites without yellow margin............................................................................ C. sollicitus Laferté-Sénectère, 1851

- Elytra green or bluish-green, with metallic sheen and a yellow marginal band..................................... 2

2. Yellow marginal band of elytra reaching the 8 th striae........................................................ 3

- Yellow marginal band of elytra reaching partially or only all of the 7 th striae (or even the 6 th striae).................... 4

3. Smaller species (9–11.5 mm); abdominal sternites narrowly marginated with yellow colour..... C. angustatus Dejean, 1831

- Larger species (>11.5 mm); abdominal sternites all blackish or dark brown....... C. melancholicus Laferté-Sénectère, 1851

4. Yellow marginal band of elytra reaching the 7 th striae only in its posterior third or along all the striae (or even the middle of the 7 th interval).......................................................................................... 5

- Yellow marginal band of elytra reaching only the 6 th or even the 5 th striae........................................ 11

5. Apex of the median lobe of aedeagus in dorsal view strongly enlarged and bent towards the left side [see fig. 13b in Kirschenhofer (2019)]; the upper edge of the yellow elytral band in the posterior region slightly dented, invading all the apical intervals; abdominal sternites narrowly marginated with yellow colour........................... C. cylindricollis Dejean, 1831

- Apex of the median lobe of aedeagus (in dorsal view) slightly (or not enlarged) and bent towards the left side............ 6

6. Larger species (13–16 mm)............................................................................. 7

- Smaller species (10–13 mm)........................................................................... 10

7. Body length (14–16 mm); median lobe knee shaped at the base................................................ 8

- Body length (13–14 mm); median lobe not knee shaped at the base............................................. 9

8. Apical lamella of the median lobe of aedeagus with a strong tooth bending downward in the left side [see fig. 12b in Kirschenhofer (2019)]; the upper edge of the yellow elytral band in the posterior region dented, invading the 2 nd, the 4 th and the 6 th apical intervals; abdominal sternites brownish, lighter at the lateral edges........................... C. sellatus Dejean, 1831

- Median lobe of aedeagus (in dorsal view) arcuate inwards just prior to apex, enlarged and acute at both sides of apex, toothed upward laterally [see fig. 9 in Kirschenhofer (2019)].................................. C. helios Kirschenhofer, 2019

9. Pronotum cordiform, lateral sulci deep, slightly arcuate inwards, reaching the middle region of the disk; apical lamella of the median lobe of aedeagus rounded in dorsal view, toothed upward laterally ( Fig. 2d )...................... C. silvai n. sp.

- Pronotum almost cylindrical-shaped, lateral sulci deep, straight, not reaching the middle region of the disk; apical lamella of the median lobe of aedeagus large and rounded, slightly bent to the left (dorsal view), untoothed laterally ( Fig. 1d ).......................................................................................... C. kirschenhoferi n. sp.

10. Male genitalia as in Kirschenhofer (2019, fig. 11)........................... C. anthracoderus Laferté-Sénectère, 1851

- Male genitalia as in Kirschenhofer (2019, fig. 16)........................... C. denticulatus denticulatus Dejean, 1831

11. Larger species (14–16 mm); median lobe of aedeagus in dorsal view arcuate inwards just before the apex, enlarged and acute at both sides of apex, toothed upward in each side [see fig. 9 in Kirschenhofer (2019)]....... C. helios Kirschenhofer, 2019

- Smaller species (10–13 mm); median lobe of aedeagus (in dorsal view) not as above.............................. 12

12. Elytra broadly oval-shaped; male genitalia as in Kirschenhofer (2019, fig. 14).................. C. dorsalis Dejean, 1831

- Elytra subparallel sided; male genitalia as in Kirschenhofer (2019, fig. 16)........ C. denticulatus denticulatus Dejean, 1831

Figures

FIGURE 1. Chlaenius (Chlaeniostenus) kirschenhoferi n. sp. (a) habitus, holotype male (dorsal view); (b) habitus, holotype male (ventral view); (c) and (d) median lobe of aedeagus, holotype male (lateral and dorsal views, respectively); (e) right and left parameres of aedeagus, holotype male (lateral view).

FIGURE 2. Chlaenius (Chlaeniostenus) silvai n. sp. (a) habitus, holotype male (dorsal view); (b) habitus, holotype male (ventral view); (c) and (d) median lobe of aedeagus, holotype male (lateral and dorsal views, respectively); (e) right and left parameres of aedeagus, holotype male (lateral view).