Key to males of Plumarius from Argentina north of Patagonia

1. Lateral ocelli in frontal view reaching or surpassing upper margin of head (Fig. 21A).............................. 2

- Lateral ocelli in frontal view not reaching upper margin of head (Figs 2 A–18A)................................... 4

2. Malar area as long as apical width of F1; lower area of genal bridge close to mandibular articulation with carinae (Fig. 21 B) (Vertex smooth anteriorly, without punctures)................................ P. stangei Diez, Fidalgo & Roig-Alsina

- Malar area 1.3–1.9 × as long as apical width of F1; lower area of genal bridge close to mandibular articulation smooth, without carinae............................................................................................. 3

3. Vertex densely punctate anteriorly; metatrochanter with ventral setose area, such area absent on ventral surface of coxa........................................................................ P. culminatus Diez, Fidalgo & Roig-Alsina

- Vertex smooth anteriorly, without punctures; metacoxa and, metatrochanter with ventral setose areas..... P. willinki Fidalgo

4. Radiating striae arising close to anterior mandibular articulation running up to malar area, antennal insertion and supraclypeal area; clypeus with at least few striae laterally; aedeagus with preapical spines (except P. s p in i fe r u s)................... 5

- Radiating striae absent, a single furrow runs from near anterior mandibular articulation to antennal insertion; clypeus without striae; aedeagus without preapical spines..................................................... P. politus sp. nov.

5. Face in lateral view not bigibbous, either clypeus or supraclypeal area alone strongly convex, or both slightly convex to flat..................................................................................................... 6

- Face in lateral view bigibbous, due to convex clypeus and convex supraclypeal area (Fig. 21 C)......... P. hirticornis André

6. Metacoxa on under surface with specialized setose area (Fig. 21 D).............................................. 7

- Metacoxa on under surface with hairs sparse, similar to those under mid coxa..................................... 10

7. Maxillary palp short, segments 4–6 as long as or shorter than segment three; scape basally swollen or projected.......... 8

- Maxillary palp long, segments 4–6 1.3–1.6 × as lon as segment 3; scape without basal swellings or projections............................................................................................. P. filipalpis Roig -Alsina

8. Supraclypeal area with step-like protuberance (Fig. 21 E); scape basally with ventral compressed, rounded expansion............................................................................................. P. gradifrons Diez

- Supraclypeal area flat in profile; scape cylindrical or projected into spine........................................ 9

9. Scape with basal spiniform projection (Fig. 21 F); maginal cell with anterior margin 2.6 × posterior margin................................................................................................. P. spiniferus Roig-Alsina

- Scape cylindrical (Fig. 3 C); marginal cell with anterior margin 1.8–2.2 × posterior margin.......... P. sarophorus sp. nov.

10. T7 with median longitudinal carina (Fig. 4 D).............................................................. 11

- T7 without median longitudinal carina................................................................... 12

11. Clypeus with a globular median prominence (Fig. 4 C); marginal cell with anterior margin 2.4 × longer than posterior margin.................................................................................... P. globulosus sp. nov.

- Clypeus slightly convex to flat; marginal cell with anterior margin 3.2 × longer than posterior margin … P. angulatus sp. nov.

12. Median ocellus in frontal view crossed by (Figs 1, 4 A), or tangent to (Fig. 9 A) supra-torular line; genal carina present.... 13

- Median ocellus in frontal view above supra-torular line (Fig. 14 A); genal carina usually absent....................... 20

13. Marginal cell with anterior margin 2.5–3.0 × longer than posterior margin........................................ 14

- Marginal cell with anterior margin 1.9–2.4 × longer than posterior margin...................................... 16

14. Area anterior to pronotal lobe smooth; propodeum behind spiracle not swollen......................... P. no a sp. nov.

- Area anterior to pronotal lobe with striae; propodeum elevated behind spiracle.................................... 15

15. Malar area short (1.0–1.1 × apical width of F1); outer margins of malar areas in frontal view diverging from margin of eye to margin of mandible (Fig. 7 A, arrow); punctures of anterior part of mesoscutum usually not extending beyond notauli; apex of paramere rounded..................................................................... P. divergens sp. nov.

- Malar area long (1.3–1.8 × apical width of F1); outer margins of malar areas in frontal view parallel (Fig. 8 A); punctures of anterior part of mesoscutum extending beyond notauli on anterior dorsal surface; apex of paramere truncate (Fig. 8 D, F).......................................................................................... P. malaris sp. nov.

16. Median ocellus in frontal view tangent to supra-torular line (Fig. 9 A); torulus separated from lateral ocellus by 0.80 × distance to margin of clypeus.................................................................... P. gracilior sp. nov.

- Median ocellus in frontal view crossed by supra-torular line (Fig. 10 A); torulus separated from lateral ocellus by 0.30–0.40 × distance to margin of clypeus........................................................................... 17

17. F1 short, approximately as long as distance from upper margin of clypeus to lower margin of median ocellus (1:1.0–1.2) (Fig. 1, a).............................................................................................. 18

- F1 longer than distance from upper margin of clypeus to lower margin of median ocellus (1: 1.3–1.4)............... … 19

18. Head in frontal view as wide as long; lateral ocelli in frontal view usually above imaginary line tangent to upper margin of eyes (Fig. 10 A)............................................................................ P. riojanus sp. nov.

- Head in frontal view 1.3 wider than long; lateral ocelli in frontal view crossed by imaginary line tangent to upper margin of eyes (Fig. 11 A).................................................................... P. exophthalmus sp. nov.

19. Propodeum swollen behind spiracle; clypeus in profile nearly flat (Fig. 12 C)....................... P. planatus sp. nov.

- Propodeum not swollen behind spiracle; clypeus in profile more convex (Fig. 13 C)................ P. albinervis sp. nov.

20. Scape basally without ventral rounded projection.......................................................... 21

- Scape basally with ventral rounded projection (Fig. 14 C)........................................ P. t u m i d u lu s Papp

21. Apical margin of clypeus pointed (Fig. 16 A) or rounded; clypeus 1.3–1.4 × wider than high; protarsomere 1 with two outer lat- eral spines......................................................................................... 22

- Apical margin of clypeus nearly straight; clypeus transverse (1.6 × wider than high) (Fig. 15 A); protarsomere 1 without outer lateral spines......................................................................... P. truncatus sp. nov.

22. Marginal cell with anterior margin 2.1 × as long as posterior margin, or longer, apex of cell narrowed................. 23

- Marginal cell with anterior margin at most 1.8 × as long as posterior margin, apex of cell obtuse.................... 24

23. OOD 2.7–3.0 × maximum diameter of lateral ocellus...................................... P. mikrommatus sp. nov.

- OOD 1.8 × maximum diameter of lateral ocellus............................................. P. obscurus sp. nov.

24. Torulus closer to lateral ocellus than to clypeus (1.4:2.0–1.2:2.0); marginal cell narrowed in central area, shortest distance between pterostigma and vein 4Rs, 0.28 × length of posterior margin of cell (r–rs) (Fig. 18 D).......... P. gracilis sp. nov.

- Torulus nearly as close to lateral ocellus as to clypeus (1.4:1.5); marginal cell wider in central area, shortest distance between pterostigma and vein 4RS, 0.55–0.70 × length of posterior margin of cell........................................ 25

25. OOD 1.6–1.7 × maximum diameter of elipsoidal lateral ocellus; lateral striae of clypeus extending on lateral third of clypeus...................................................................................... P. fidalgoi sp. nov.

- OOD 2.3–2.5 × maximum diameter of lateral ocellus, which is nearly circular; lateral striae of clypeus extending on lateral fourth of clypeus..................................................................... P. ocellulatus sp. nov.