Key to Hylomyrma species

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

1

Propodeal lobe bidentate (Fig. 3B) => 2
Propodeal lobe unidentate, dorsal region rounded (Fig. 3A) (Peru) => Hylomyrma wachiperi

Figure 3. Lateral view of propodeum; propodeal lobe outlined. A) H. wachiperi (MZSP67468); B) H. mariae paratype (MZSP67393).

2

return to couplet #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

return to couplet #2

Dorsal margin of petiole strongly convex (Fig. 4A) => 4
Dorsal margin of petiole slightly convex (Fig. 4B) => 6

4

return to couplet #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) => 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

5

return to couplet #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) => 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

Figure 4. Lateral view of petiole; dorsal margin of petiole outlined. A) H. margaridae paratype (USNMENT00688844); B) H. reginae (USNMENT00688778); C) H. columbica (COLOMBIA: on fiber plant from Colombia at Quarantine [USNM]).

Figure 5. Frontal view. A) H. villemantae (MZHY199 [MZSP]), photo by M.A. Ulysséa; B) H. peetersi paratype (USNMENT00413896); C) H. margaridae paratype (USNMENT00688844), photos by Ricardo Kawada.

Figure 6. Lateral view of mesosoma. A) H. margaridae paratype (USNMENT00688844); B) H. peetersi paratype (USNMENT00413896).

6

return to couplet #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

return to couplet #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) => 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

return to couplet #6

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

9

return to couplet #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) => [[Hylomyrma reginae
Subtriangular projection on ventral surface of petiole absent; subpostpetiolar process less prominent (Fig. 10C–D) => 10

Figure 7. Lateral view of procoxa. A) H. lispectorae paratype (MZSP67347); B) H. columbica (COLOMBIA: on fiber plant from Colombia at Quarantine [USNM]).

Figure 8. Lateral view of mesosoma. A) H. montana (MZSP67433); B) H. lispectorae paratype (MZSP67347).

Figure 9. Lateral view of head; eye format outlined. A) H. jeronimae paratype (MZSP67341); B) H. blandiens (MZSP67435).

10

return to couplet #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) => Hylomyrma immanis
Integument shinier, covered with thick striae, interspaces distinguishable => 11

11

return to couplet #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) => 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

return to couplet #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

Figure 10. Lateral view of petiole and postpetiole; projection on mesoventral surface of petiole (black) and subpostpetiolar process (white) pointed. A) H. reginae (USNMENT00688778); B) drawing of H. reginae holotype from Kutter, 1977; C) H. immanis (MZSP67335); D) H. praepotens (MZSP67411).

Figure 11. Dorsal view of mesosoma. A-B) H. marielleae paratype (MZSP67399); C) H. longiscapa (MZSP67436).

13

return to couplet #12

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

return to couplet #12

Interspaces between striae on mesosomal dorsum indistinguishable (Fig. 12A) => 15
Interspaces between striae on mesosomal dorsum smooth (Fig. 12B) => 21

Figure 12. Dorsal view of mesosoma; striae type (regular) outlined. A) H. blandiens (MZSP67435); B) H. reitteri (MZSP67443).

15

return to couplet #14

Mesonotal striae predominantly longitudinal (Fig. 12A–B) => 16
Mesonotal striae predominantly transverse (Fig. 13A–C) => 19

Figure 13. Dorsal view of pronotum and mesonotum; striae direction outlined. A) H. transversa (MZSP67452); B) H. columbica (COLOMBIA: on fiber plant from Colombia at Quarantine [USNM]); C) H. dolichops (COLOMBIA: Nariño: Orito, Territorio Kofan, 00°30’N, 77°13’W, 700m, Bosque caída, T2T6 [IHVL]).

16

return to couplet #15

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

17

return to couplet #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) => 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

Figure 14. Dorsal view of petiole and postpetiole. A) H. macielae paratype (MZSP67389); B) H. blandiens (MZSP67435); C) H. dentiloba (MZSP67320).

18

return to couplet #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) => 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

return to couplet #15

Striae on mesonotum predominantly straigh (Fig. 13A) (Bolivia, Brazil, Colombia, Peru) => Hylomyrma transversa
Striae on mesonotum semicircular (Fig. 13B–C) => 20

20

return to couplet #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) => 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

return to couplet #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

Figure 15. Frontal view. A) H. virginiae paratype (ECUADOR: Pichincha, 584 [IHVL]); B) H. mitiae holotype (MZSP67401), photo by Gabriel Biffi; C) H. reitteri (MZSP67443); D) H. dandarae paratype (COLOMBIA: Caquetá [IHVL]); E) H. adelae paratype (MZSP67312).

22

return to couplet #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) => 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

return to couplet #21

Striae on mesosoma rugose (Fig. 16A) => 24
Striae on mesosoma regular (Fig. 12B) or irregular (Fig. 16B) => 29

Figure 16. Dorsal view of mesosoma; striae type (A: rugose, B: irregular) outlined. A) H. balzani (MZSP67434); B) H. versuta (MZSP67461).

24

return to couplet #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) => Hylomyrma primavesi

25

return to couplet #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

return to couplet #25

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

27

return to couplet #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) => 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

return to couplet #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) => 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

return to couplet #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) => 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

Figure 17. Dorsal (A-B) and lateral (C) view of mesosoma; promesonotal junction and metanotal groove outlined. A) H. dandarae paratype (COLOMBIA: Caquetá [IHVL]); B) H. primavesi paratype (MZSP67418); C) H. primavesi paratype (MZSP67418).

Figure 18. Dorsal view of postpetiole and gaster. A) H. versuta (MZSP67461); B) H. lopesi paratype (MZSP67385).

30

return to couplet #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) => 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

References

Ulyssea, M.A., Brandao, C.R.F. 2021. Taxonomic revision of the Neotropical ant genus Hylomyrma Forel, 1912 (Hymenoptera: Formicidae: Myrmicinae), with the description of fourteen new species. Zootaxa 5055, 1–137 (doi:10.11646/zootaxa.5055.1.1).