Key to Mexican species of Labena

1. Thorax coarsely punctate; punctures on mesopleuron separated by about their diameter. [Head with blackish band through ocelli. Wings usually more or less infuscate]............................................................ L. grallator (Say), ♀ ♁

– Thorax smooth or finely punctate; mesopleuron usually polished, impunctate or very finely and sparsely punctate.............................................................2

2. Fore wing hyaline with a distinct blackish spot near distal end of marginal cell (Fig. 8). Metasoma in female sometimes very slender, 2.0-3.7 times as long as posteriorly broad......................................................................................... 3

– Fore wing hyaline or yellowish, without an apical blackish spot. Metasoma in female quite stout, first tergite 1.6-2.0 times as long as posteriorly broad ...14

3. Female ........................................................................................................4

– Male ...........................................................................................................9

4. Flagellum, in dorsal view, with either a very pale median band, or with basal 0.7 pale yellowish brown, with distal apex black. Metasoma bicolored, tergites 2-7 widely black anteriorly, with yellow band posteriorly. [Mid tibia with a row of stout dark flattened bristles on outer surface] .......... L. espinita Gauld

– Flagellum, in dorsal view, more or less uniformly black. Metasoma more or less unicolourous, sometimes with median longitudinal stripes on first tergite ......................................................................................................... 5

5. Head, in dorsal view, with a transverse black mark immediately in front of occipital carina. [Propodeum with area basalis half as long as wide. Legs yellow, hind coxa with a dorsal black spot (in material from Costa Rica) or without (in specimens from México)] ............................................... L. zerita Gauld

– Head, in dorsal view, yellow to brownish (Fig. 7), at most slightly darker brown close to occipital carina ....................................................................6

6. Clypeus with lower margin truncate, with a very strong transverse raised crest parallel and close to lower margin.................................. L. gloriosa Cresson

– Clypeus with lower margin strongly convex, with lower region flat, without transverse crest near lower margin............................................................... 7

7. First tergite yellow with a median longitudinal black stripe. Ovipositor extending beyond apex of metasoma by about 2.6 times length of hind tibia. Propodeum with lateral end of posterior transverse carina quite strongly raised into a low, rounded flange, displaced forwards, slightly overhanging the area lateralis ........................................................................ L. schausi Cushman

– First tergite without longitudinal black stripe, more or less uniformly yellow to brown. Ovipositor extending beyond apex of metasoma by 1.5-1.9 times length of hind tibia. Propodeum with lateral end of posterior transverse carina raised or not raised into rounded flange ............................................... 8

8. Propodeum with area lateralis small, of subequal area to area coxalis. Basal area usually slightly transverse. Mesoscutum yellow with three distinct brown longitudinal marks............................................................. L. tarsata Gauld

– Propodeum with area lateralis large, of much greater area than area coxalis. Basal area usually elongate, rarely almost as long as wide. Mesoscutum yellow to brown, without distinct longitudinal marks.................. L. eremica Gauld

9. Flagellum, in dorsal view, yellowish with distal apex black ........................ 10

– Flagellum, in dorsal view, more or less entirely black or blackish brown....11

10. Tergite 3 with hind margin transverse or very weakly concave. Outer surface of mid tibia with 4-5 large conspicuous dark bristles. Head, in dorsal view, with a transverse black mark immediately in front of occipital carina. Mesopleuron yellow with black marks near anterior and posterior margins. Propodeum widely black anteriorly and laterally ........................ L. espinita Gauld

– Tergite 3 with hind margin strongly concave. Outer surface of mid tibia with weak inconspicuous bristles. Mesopleuron yellow, without black marks. Propodeum yellow, sometimes brownish near anterior margin ...... L. tarsata Gauld

11. Tergites 3-5 with hind margins more or less straight. Posterior transverse carina of propodeum laterally very strongly raised........................................12

– At least some of tergites 3-5 with hind margins concave. Posterior transverse carina of propodeum laterally not noticeably strongly raised..................... 13

12. Clypeus with lower margin truncate, with a very strong transverse raised crest parallel and close to lower margin. First tergite more or less entirely yellowish brown............................................................................ L. gloriosa Cresson

– Clypeus with lower margin strongly convex, with lower region flat, without transverse crest near lower margin. First tergite yellow with a median longitudinal black stripe.......................................................... L. schausi Cushman

13. Propodeum with area dentipara open posteriorly. Mesoscutum more or less brownish yellow to yellowish, sometimes infuscate centrally... L. eremica Gauld

– Propodeum with area dentipara completely enclosed. Mesoscutum yellow with three black longitudinal marks..................................... L. zerita Gauld

14. First sternite without a central transverse ridge. Propodeum with area superomedia closed by a carina posteriorly, thus discrete from area petiolaris which is usually replaced by a single median longitudinal carina. Head in dorsal view with gena moderately narrowed behind eyes. Mid leg in female with second tarsomere transverse, about as long as third and fourth tarsomeres together. Tergites 3-5 in male slightly transverse with hind margin straight... ............................................................................. L. marginata Szépl., ♀ ♁

– First sternite with a distinct central transverse ridge (Fig. 4). Propodeum with area superomedia open posteriorly, broadly confluent with area petiolaris (Fig. 5). Head in dorsal view with gena strongly narrowed behind eyes (Fig. 2). Mid leg in female with second tarsomere longer than broad, longer than third and fourth tarsomeres together. Tergites 3-5 in male strongly transverse, with hind margin conspicuously concave (male of L. acerba sp. n. unknown)...15

15. Flagellum almost entirely black, narrowly yellowish basally and apically, without a pale median band (Fig. 3). Propodeal area which is comprised by the confluent areas superomedia and petiolaris slightly transverse, 0.9 times as long as maximally broad (Fig. 5). Body yellow except for three brownish longitudinal marks on mesoscutum ..................................... L. acerba sp. n., ♀

– Flagellum blackish with a central yellowish band in female, and with proximal 0.7 or more yellowish orange and distal apex black in male. Propodeal area which is comprised by the confluent areas superomedia and petiolaris distinctly elongate, almost 1.5 times as long as maximally broad. Body yellow with black marks on occiput along occipital carina, around ocelli, on mesoscutum, on peripheries of mesoscutum, scutellum and mesopleuron, and on carinae bordering area lateralis of propodeum............... L. guanacasteca Gauld, ♀ ♁