Key to Horismenus species associated with bruchid beetles

1 Scutellum flat, partly to predominantly smooth (Figs 2, 6, 75).................................................. 2

- Scutellum distinctly convex, usually predominantly to completely reticulate (e.g. Fig. 20) (in H. distinguendus scutellum is smooth, but distinctly convex—see below)................................................................. 4

2 Female gaster very long, MM/LG = 0.6–0.7 (Fig. 74), posterior part of tergite I reticulate (Fig. 74); male scape inflated and dark in colour (Fig. 77)......... H. gabrielae sp. nov. (♀, ♂) (Mexico, from unidentified bruchids in seeds of Leucaena sp.)

- Female gaster shorter, MM/LG = 1.0–1.1 (Figs 15–16), posterior part of tergite I with punctures (Figs 15–16); male scape more slender and predominantly pale in colour (4, 8)......................................................... 3

3 Female gaster with apex pointed (Fig. 16); mesoscutum and scutellum dull golden-green (Fig. 2)............................................. H. depressus Gahan (♀, ♂) (USA (Arizona & Texas (new records), California, from Stator spp.)

- Female gaster with apex more blunt (Fig. 15); mesoscutum and scutellum bright metallic bluish-green (Fig. 6), sometimes also with purple tinges...................... H. depressoides sp. nov. (♀, ♂) (Honduras, Mexico, from Acanthoscelides sp.)

4 Femora dark brown or metallic........................................................................... 5

- Femora yellowish-white or yellowish-brown................................................................ 6

5 Scutellum smooth and shiny (Fig. 70); propodeum with median carina wide and expanding towards posterior part (Fig. 70)….......................................................................... H. distinguendus Blanchard (♀) (Argentina, Brazil, from an unidentified bruchid – morphologically this species is different from most other species associated with bruchids and also has several other host records (see Hansson 2009); it is possibly a hyperparasitoid)

- Scutellum with strong reticulation (Fig. 71); propodeum with median carina narrow and with sides more or less parallel (Fig. 71)............................ H. puniceus Hansson (♀, ♂) (Chile, Uruguay, from Pseudopachymeria spinipes (Er.))

6 Frons lateral to anterior ocellus with strong engraved reticulation (Fig. 69).................... H. erasmus Hansson (♂) (Ecuador, from an unidentified bruchid)

- Frons lateral to anterior ocellus with strong raised reticulation (e.g. Fig. 25)....................................... 7

7 Antennal scrobes join frontal suture separately (Fig. 68)...................................... H. perus Hansson (♀) (Peru, host unknown but possibly bruchids as the species is similar to H. missouriensis)

- Antennal scrobes join below frontal suture (as in e.g. Fig. 25) (in some specimens, especially males, scrobes join on frontal suture).............................................................................................. 8

8 Gaster with 1 st tergite with medioposterior part with reticulation....................... H. productus (Ashmead) (♀, ♂) (USA (New Mexico), from Bruchus amicus Horn)

- Gaster with 1 st tergite with medioposterior part with punctures (in some specimens almost smooth)..................... 9

9 Head and mesosoma black with metallic tinges..................................... H. bruchophagus Burks (♀, ♂) (USA (Texas), from Mimosestes sallaei (Sharp))

- Head and mesosoma bright metallic bluish-green to golden-green.............................................. 10

10 Female flagellum short (Figs 50, 54, 62, 66), e.g. 1 st flagellomere 1.8-2.1× as long as wide; male scape inflated (Figs 51, 55), 2.8× as long as wide.................................................................................. 11

- Female flagellum long (Figs 18, 24, 46), e.g. 1 st flagellomere 2.8-3.5× as long as wide; male scape narrow (Figs 19, 47), 4.1– 4.5× as long as wide (male unknown in H. multistriatus)...................................................... 12

11 Head stout (Fig. 64), in dorsal view 2.0× as wide as long; flagellum short (Figs 54, 55, 66), 1.6× as long as scape in female, 1.7× in male; male scape predominantly dark with at most basal ¼ pale (Fig. 55)................ H. stator sp. nov. (♀, ♂) (USA (Arizona), from Stator spp.)

- Head less stout (Fig. 60), in dorsal view 2.3× as wide as long; flagellum long (Figs 50, 51, 62), 1.9× as long as scape in female, 2.3× in male; male scape with apical ¼ dark and basal ½ pale (Fig. 51).............. H. missouriensis (Ashmead) (♀, ♂) (with large distribution, recorded from the USA (New York) southwards to Argentina (Hansson 2009), many hosts - see Hansson (2009)).

12 Propodeum with anterolateral foveae predominantly smooth (Fig. 39); gaster with 1 st tergite with medioposterior part with elongate punctures (Fig. 42)......................... H. multistriatus sp. nov. (♀) (Mexico, from Acanthoscelides sp.)

- Propodeum with anterolateral foveae predominantly reticulate (Figs 37, 38); gaster with 1 st tergite with medioposterior part with round punctures (Figs 40, 41)....................................................................... 13

13 Propodeum with anterolateral foveae with lateral margin rounded (Fig. 37); female 1 st flagellomere longer (3.1× as long as wide) (Fig. 34); male thoracic dorsum and vertex metallic bluish-green (Fig. 45)...... H. butcheri Hansson & Aebi (♀, ♂) (Mexico, USA (New Mexico), from Acanthoscelides sp. and Bruchus amicus)

- Propodeum with anterolateral foveae with lateral margin straight (Fig. 38); female 1 st flagellomere shorter (2.2× as long as wide) (Fig. 35); male thoracic dorsum and vertex golden-red (Fig. 21)........................ H. dennoi sp. nov. (♀, ♂) (Mexico, from Acanthoscelides sp.)