Key to species of Hylomyrma based on workers

1. Propodeal lobe bidentate (Fig. 3B)........................................................................ 2

- Propodeal lobe unidentate, dorsal region rounded (Fig. 3A) (Peru)................................ H. wachiperi n. sp.

2(1). Dorsal margin of petiole continuous, anterior surface of node not differentiated from anterior peduncle (Fig. 4A–B)....... 3

- Dorsal margin of petiole discontinuous, anterior surface of node differentiated from anterior peduncle (Fig. 4C)......... 12

3(2). Dorsal margin of petiole strongly convex (Fig. 4A).......................................................... 4

- Dorsal margin of petiole slightly convex (Fig. 4B)........................................................... 6

4(3). Striae on dorsal surface of head with smooth crests (Fig. 5A); mesosoma with a few elliptic and concentric striae; postetiolar dorsum and gaster smooth (Brazil)............................................................. H. villemantae

- Striae on dorsal surface of head with punctuated appearance (Fig. 5B–C); mesosoma longitudinally striate; postpetiolar dorsum and base of first gastral segment with longitudinal striae...................................................... 5

5(4). In lateral view, striae of mesosoma directed to propodeal spine (Fig. 6A); petiole mesoventral surface armed with conspicuous spine; petiolar dorsum with transverse and longitudinal striae; subpostpetiolar process more prominent (SPP 0.13–0.14 mm) (Guyana, French Guiana)............................................................... H. margaridae n. sp.

- In lateral view, striae of mesosoma directed to propodeal dorsum (Fig. 6B); petiole mesoventral surface armed with inconspicuous subtriangular projection; petiolar dorsum entirely covered with transverse striae; subpostpetiolar process less prominent (SPP 0.11–0.12 mm) (Guyana, Venezuela).................................................... H. peetersi n. sp.

6(3). Procoxa striae with variable thickness (Fig. 7A); postpetiolar dorsum predominantly smooth......................... 7

- Procoxa striae with uniform thickness (Fig. 7B); postpetiolar dorsum striate....................................... 8

7(6). Regular and irregular striae on mesosoma, interspaces between striae smooth; dorsal margin of mesosoma somewhat straight (mesosoma slightly flattened dorsally) (Fig. 8A) (Costa Rica, Ecuador, Panama)........................... H. montana

- Mesosoma covered with irregular to vermicular striae of variable thickness, interspaces indistinguishable; dorsal margin of mesosoma notably convex (Fig. 8B) (Colombia, Ecuador)...................................... H. lispectorae n. sp.

8(6). Eye reniform (Fig. 9A); propodeal spine relatively short (PSL 0.21–0.24 mm) (Costa Rica, Panama)..... H. jeronimae n. sp.

- Eye drop-shaped (anterior region narrower than posterior region) (Fig. 9B); propodeal spine relatively long (PSL 0.25–0.58 mm)................................................................................................ 9

9(8). Subtriangular projection on mesoventral surface of petiole present (anterior to petiolar spiracle) (Fig. 10A–B); subpostpetiolar process very prominent (Fig. 10A) (Brazil, Guyana, French Guiana, Suriname)............................. H. reginae

- Subtriangular projection on ventral surface of petiole absent; subpostpetiolar process less prominent (Fig. 10C–D)....... 10

10(9). Integument predominantly subopaque, covered with very thin striae (microsculpture) superimposed on vermicular striae (macrosculpture), interspaces between striae indistinguishable (Bolivia, Brazil, Colombia, Ecuador, Guyana, French Guiana, Peru, Trinidad and Tobago, Venezuela)................................................................. H. immanis

- Integument shinier, covered with thick striae, interspaces distinguishable........................................ 11

11(9). Regular to irregular striae on mesosoma; transverse striae on petiolar dorsum; sternite of the first gastral segment with semicircular striae covering the midbasal and lateral regions (Brazil, Colombia, Ecuador)........................ H. praepotens

- Vermicular striae on mesosoma; petiolar dorsum mostly covered with irregular to vermicular striae; sternite of the first gastral segment with striation restricted to laterobasal region (Colombia)......................................... H. sagax

12(2). Antennal scape relatively long, surpassing the posterior margin of head in full-face view (SI 88.37–100 mm); vermicular striae on mesonotum (Fig. 11A).............................................................................. 13

- Antennal scape relatively short, never surpassing the posterior margin of head in full-face view (SI 65.16–81.81 mm); mesonotum striae variously shaped, but never vermicular........................................................... 14

13(12). Thick, dark and unbranched setae (Fig. 11B) (Bolivia, Brazil, Ecuador, French Guiana, Peru).......... H. marielleae n. sp.

- Thin, light and branched setae (Fig. 11C) (Brazil, Ecuador, Peru, Suriname, Venezuela).................... H. longiscapa

14(12). Interspaces between striae on mesosomal dorsum indistinguishable (Fig. 12A).................................... 15

- Interspaces between striae on mesosomal dorsum smooth (Fig. 12B)............................................ 21

15(14). Mesonotal striae predominantly longitudinal (Fig. 12A–B)................................................... 16

- Mesonotal striae predominantly transverse (Fig. 13A–C)..................................................... 19

16(15). Body covered with conspicuous and branched setae, trifid (Costa Rica).................................. H. plumosa

- Body mostly covered with thin and unbranched setae; if branched setae present, they are inconspicuous................ 17

17(16). Eye oval; metanotal groove distinguished by a slight depression; propodeal spine long (PSL 0.28–0.34 mm); postpetiolar dorsum with longitudinal, discontinuous and slightly curved striae (Fig. 14A) (Colombia, Ecuador).......................................................................... H. macielae n. sp. (in part; specimens from Leticia, Colombia)

- Eye reniform or drop-shaped; metanotal groove indistinct; propodeal spine short (PSL shorter than 0.27 mm); postpetiolar dorsum with longitudinal, continuous and regular striae (Fig. 14B–C)........................................... 18

18(17). Dorsal margin of mesonotum convex dorsally; propodeal spine slightly longer than the dorsal tooth of propodeal lobe (PSL 0.20–0.27 mm); striae length on first gastral segment similar to postpetiolar length (Fig. 14B) (Bolivia, Brazil, Colombia, Ecuador, Guyana, French Guiana, Peru, Suriname, Trinidad and Tobago, Venezuela)......................... H. blandiens

- Dorsal margin of mesonotum straight (mesonotum flattened dorsally); propodeal spine very short (PSL 0.15–0.16 mm), shorter than the dorsal tooth of propodeal lobe; striae length on first gastral segment shorter than postpetiolar length, restricted to basal region (Fig. 14C) (Panama).................................................................... H. dentiloba

19(15). Striae on mesonotum predominantly straigh (Fig. 13A) (Bolivia, Brazil, Colombia, Peru).................. H. transversa

- Striae on mesonotum semicircular (Fig. 13B–C)............................................................ 20

20(19). Eye midsize (MOD 0.21–0.24 mm), 13 facets at maximum diameter, drop-shaped; propodeal spine short (shorter than 2× the dorsal tooth of propodeal lobe); first half of petiolar node dorsum with semicircular striae, and second half with longitudinal striae; unbranched setae with sharp tip (Colombia, Venezuela)........................................ H. columbica

- Eye large (MOD 0.26–0.30 mm), 16–18 facets at maximum diameter, reniform; propodeal spine long (2× or longer than the dorsal tooth of propodeal lobe); dorsum of petiolar node with longitudinal striae; branched setae with lobed ends (Colombia, Ecuador, Venezuela).......................................................................... H. dolichops

21(14). Head dorsum with vermicular to vermiculated-areolated striae (Fig. 15A–B); postpetiolar dorsum and base of first gastral segment with anastomosed longitudinal striae................................................................ 22

- Head dorsum with longitudinal striae that are regular (Fig. 15C), irregular (Fig. 15D), or rugose (Fig. 15E); postpetiolar dorsum and base of first gastral segment with longitudinal striae not anastomosed........................................ 23

22(21). Gena and laterodorsal region of head covered with very thin striae (microsculpture) superimposed on vermicular to vermiculated-areolated striae (macrosculpture); dorsal margin of mesosoma continuous (LV), metanotal groove indistinct; subpostpetiolar process weak and slightly convex (Colombia, Ecuador)...................................... H. virginiae n. sp.

- Gena and laterodorsal region of head covered with very thin striae (microsculpture) between the vermicular to vermiculatedareolated striae; dorsal margin of mesosoma discontinuous (LV), metanotal groove distinguished by a slight depression (LV) and altered sculpture (DV); subpostpetiolar process prominent and subtriangular (French Guiana).......... H. mitiae n. sp.

23(21). Striae on mesosoma rugose (Fig. 16A)................................................................... 24

- Striae on mesosoma regular (Fig. 12B) or irregular (Fig. 16B)................................................. 29

24(23). Small to midsized ant (TL 4.28–5.23 mm, WL 1.08–1.40 mm); brownish body; propodeal spine longer than the dorsal tooth of propodeal lobe...................................................................................... 25

- Large-sized ant (TL 5.32–5.78 mm, WL 1.34–1.48 mm); black body; propodeal spine with length similar to the dorsal tooth of propodeal lobe (Brazil)................................................................... H. primavesi n. sp.

25(24). Posterior surface of profemur mostly smooth; base of first gastral segment with short striae, shorter than postpetiole length 26

- Posterior surface of profemur with transverse striae; first gastral segment with long striae, similar to or longer than postpetiole length............................................................................................. 28

26(25). Dorsal margin of mesosoma continuous, without differentiated metanotal groove (Fig. 16A) (Argentina, Brazil, Paraguay).............................................................................................. H. balzani

- Dorsal margin of mesosoma discontinuous, metanotal groove distinguishable by altered sculpture (Fig. 17A–B) or a slight depression (Fig. 17C)................................................................................. 27

27(26). On side of head, thinner striae (microsculpture) occur between the thicker striae (macrosculpture); striae on petiolar node mostly transverse; striae on postpetiolar tergite regular and longitudinal, striae weakly marked on lateral and posterior regions (Colombia)............................................................................ H. dandarae n. sp.

- On side of head, thinner striae are superimposed on thicker striae; striae on petiolar node mostly longitudinal; striae on postpetiolar tergite regular and longitudinal, striae well-marked (Colombia, Ecuador)........................ H. macielae n. sp.

28(25). Metanotal groove distinguished by a depression; propodeal spine very long (PSL 0.32–0.37 mm), longer than 2× the dorsal tooth of propodeal lobe; dorsum of petiolar node with rugose striae (Colombia)........................ H. mariae n. sp.

- Metanotal groove indistinct; propodeal spine short (PSL 0.22–0.26 mm), shorter than 2× the dorsal tooth of propodeal lobe; dorsum of petiolar node with irregular and transverse striae (Bolivia)................................ H. adelae n. sp.

29(23) Longitudinal striae on head dorsum irregular and with variable thickness; striae on mesosomal dorsum irregular, interspaces in part smooth and in part with thin striation; longitudinal striae on first gastral tergite slightly shorter than postpetiolar length (Fig. 18A) (Belize, Colombia, Costa Rica, Guatemala, Honduras, Mexico, Nicaragua, Panama)..................... H. versuta

- Longitudinal striae on head dorsum regular (Fig. 15C); striae on mesosomal dorsum regular to irregular, interspaces smooth (Fig. 12B); longitudinal striae on first gastral tergite slightly shorter than 1 / 3 of postpetiolar length (Fig. 18B)............ 30

30(29). Striae between frontal carina (posterior to torulus) and eye margin irregular; in lateral view, mesosomal striae directed to propodeal dorsum; ventral surface of petiole smooth (Brazil, Paraguay)...................................... H. reitteri

- Striae between frontal carina and eye margin rugose; in lateral view, mesosomal striae directed to propodeal spine; ventral surface of petiole striate (Brazil).............................................................. H. lopesi n. sp.