Key to Hylomyrma species

The following key to Hylomyrma species is based on Ulyssea & Brandao (2021).

1

 * Propodeal lobe bidentate (Fig. 3B)
 * Propodeal lobe unidentate, dorsal region rounded (Fig. 3A) (Peru) Hylomyrma wachiperi

2

 * Dorsal margin of petiole continuous, anterior surface of node not differentiated from anterior peduncle (Fig. 4A–B)
 * Dorsal margin of petiole discontinuous, anterior surface of node differentiated from anterior peduncle (Fig. 4C)

3

 * Dorsal margin of petiole strongly convex (Fig. 4A)
 * Dorsal margin of petiole slightly convex (Fig. 4B)

4

 * 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) Hylomyrma 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

 * 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) Hylomyrma margaridae
 * 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) Hylomyrma peetersi

6

 * Procoxa striae with variable thickness (Fig. 7A); postpetiolar dorsum predominantly smooth
 * Procoxa striae with uniform thickness (Fig. 7B); postpetiolar dorsum striate

7

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

8

 * Eye reniform (Fig. 9A); propodeal spine relatively short (PSL 0.21–0.24 mm) (Costa Rica, Panama) Hylomyrma jeronimae
 * Eye drop-shaped (anterior region narrower than posterior region) (Fig. 9B); propodeal spine relatively long (PSL 0.25–0.58mm)

9

 * 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) ''[[Hylomyrma reginae
 * Subtriangular projection on ventral surface of petiole absent; subpostpetiolar process less prominent (Fig. 10C–D)

10

 * 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) Hylomyrma immanis
 * Integument shinier, covered with thick striae, interspaces distinguishable

11

 * 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) Hylomyrma 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) Hylomyrma sagax

12

 * 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)
 * 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

13

 * Thick, dark and unbranched setae (Fig. 11B) (Bolivia, Brazil, Ecuador, French Guiana, Peru) Hylomyrma marielleae
 * Thin, light and branched setae (Fig. 11C) (Brazil, Ecuador, Peru, Suriname, Venezuela) Hylomyrma longiscapa

14

 * Interspaces between striae on mesosomal dorsum indistinguishable (Fig. 12A)
 * Interspaces between striae on mesosomal dorsum smooth (Fig. 12B)

15

 * Mesonotal striae predominantly longitudinal (Fig. 12A–B)
 * Mesonotal striae predominantly transverse (Fig. 13A–C)

16

 * Body covered with conspicuous and branched setae, trifid (Costa Rica) Hylomyrma plumosa
 * Body mostly covered with thin and unbranched setae; if branched setae present, they are inconspicuous

17

 * 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) Hylomyrma macielae (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

 * 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) Hylomyrma 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) Hylomyrma dentiloba

19

 * Striae on mesonotum predominantly straigh (Fig. 13A) (Bolivia, Brazil, Colombia, Peru) Hylomyrma transversa
 * Striae on mesonotum semicircular (Fig. 13B–C)

20

 * 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) Hylomyrma 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) Hylomyrma dolichops

21

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

22

 * 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) Hylomyrma virginiae
 * 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) Hylomyrma mitiae

23

 * Striae on mesosoma rugose (Fig. 16A)
 * Striae on mesosoma regular (Fig. 12B) or irregular (Fig. 16B)

24

 * 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
 * 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) Hylomyrma primavesi

25

 * Posterior surface of profemur mostly smooth; base of first gastral segment with short striae, shorter than postpetiole length
 * Posterior surface of profemur with transverse striae; first gastral segment with long striae, similar to or longer than postpetiole length

26

 * Dorsal margin of mesosoma continuous, without differentiated metanotal groove (Fig. 16A) (Argentina, Brazil, Paraguay) Hylomyrma balzani
 * Dorsal margin of mesosoma discontinuous, metanotal groove distinguishable by altered sculpture (Fig. 17A–B) or a slight depression (Fig. 17C)

27

 * 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) Hylomyrma dandarae
 * 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) Hylomyrma macielae

28

 * 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) Hylomyrma mariae
 * 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) Hylomyrma adelae

29

 * 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) Hylomyrma 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

 * 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) Hylomyrma reitteri
 * Striae between frontal carina and eye margin rugose; in lateral view, mesosomal striae directed to propodeal spine; ventral surface of petiole striate (Brazil) Hylomyrma lopesi