Identification key to Brachymyrmex species

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This key to the workers of Brachymyrmex is based on Ortiz-Sepulveda et al., 2019.

1

  • Clypeus with a single long apical hair near the anterior margin, two lateral hairs medially and two hairs near the toruli (Fig. 5(a1)); monomorphic => 2
  • Clypeus with a row of long thick hairs near the anterior margin (Fig. 5(a2)), remaining pilosity not as above; dimorphic => 39

Ortiz-Sepulveda, C., Van Bocxlaer, B. et al. 2019, Fig. 5(a).jpg

2

return to couplet #1

  • Metathoracic spiracles tumuliform (i.e., strongly protruding dorsally) (Fig. 6(a1)); known only from Brazil => 3
  • Metathoracic spiracles not (Fig. 6(a2)) or slightly protruding but not tumiliform (Fig. 6(a3)); naturally occurring throughout the Neotropics => 5

Ortiz-Sepulveda, C., Van Bocxlaer, B. et al. 2019, Fig. 6(a).jpg

3

return to couplet #2

  • Toruli surpassing the posterior clypeal margin in oblique anterodorsal view (Fig. 5(a3)); head and mesosoma smooth and shiny => 4
  • Toruli touching the posterior clypeal margin but never surpassing it in oblique anterodorsal view (Fig. 5(a2)); head and mesosoma finely punctate and opaque => Brachymyrmex brasiliensis

Ortiz-Sepulveda, C., Van Bocxlaer, B. et al. 2019, Fig. 5(a).jpg

4

return to couplet #3

  • Mesosoma without erect hairs; gaster with scattered long erect hairs, except for the first segment which has dense yellowish pubescence => Brachymyrmex feitosai
  • Mesosoma with two erect hairs on pronotum and two on mesonotum; gaster with scattered long erect hairs, also on the first segment => Brachymyrmex delabiei

5

return to couplet #2

  • Dorsum of the head, mesosoma and gaster with thick erect black hairs (as in Nylanderia) that contrast with the body color (head and gaster may be darker than mesosoma) => Brachymyrmex cavernicola
  • Dorsum of the head, mesosoma and gaster without hairs, or with thin hairs that do not contrast with the body color => 6

6

return to couplet #5

  • Eyes positioned below the cephalic midline (Fig. 5(b1)), with three or four ommatidia along the maximal diameter of the eye (EL) (Fig. 5(c1)) => 7
  • Eyes usually positioned on the cephalic midline (Fig. 5(b2)), with more than four ommatidia along the maximal diameter of the eye (Fig. 5(c2)) => 9

Ortiz-Sepulveda, C., Van Bocxlaer, B. et al. 2019, Fig. 5(b).jpg

7

return to couplet #6

  • Mesonotum not bulging dorsally above the pronotum in lateral view (Fig. 6(b1)) => 8
  • Mesonotum bulging dorsally above the pronotum in lateral view (Fig. 6(b2)) => Brachymyrmex modestus

Ortiz-Sepulveda, C., Van Bocxlaer, B. et al. 2019, Fig. 6(b).jpg

8

return to couplet #7

  • Scapes short, just reaching the posterior margin of the head or surpassing it by a length shorter than the maximal diameter of the eye (Fig. 5(d1, d2)) => Brachymyrmex donisthorpei
  • Scapes long, surpassing the posterior margin of the head by a length approximately equal to the maximal diameter of the eye (Fig. 5(d3)) => Brachymyrmex myops

Ortiz-Sepulveda, C., Van Bocxlaer, B. et al. 2019, Fig. 5(d).jpg

9

return to couplet #6

  • Two erect hairs between the metathoracic spiracles => 10
  • Without erect hairs between the metathoracic spiracles => 11

10

return to couplet #9

  • Scapes surpass the posterior cephalic margin by a length of approximately 1.5× the maximal diameter of the eye (Fig. 5(d3): 2A ≤ B); hairs on scapes decumbent; body uniform in color (usually dark brown) => Brachymyrmex admotus
  • Scapes surpass the posterior cephalic margin by a length of approximately 1.0× the maximal diameter of the eye (Fig. 5(d3): 2A > B); hairs on scapes appressed; head and mesosoma light brown, gaster darker => Brachymyrmex bonariensis

Ortiz-Sepulveda, C., Van Bocxlaer, B. et al. 2019, Fig. 5(d).jpg

11

return to couplet #9

  • Dorsal margin of the mesosoma having a marked sinusoidal shape (Fig. 6(c)) => 12
  • Dorsal margin of the mesosoma not sinusoidal or only of sub-siusoidal shape (Figs. 6(a2, a3, b1, b2, d1, d2, e1 ,e2)) => 13

Ortiz-Sepulveda, C., Van Bocxlaer, B. et al. 2019, Fig. 6(a).jpg Ortiz-Sepulveda, C., Van Bocxlaer, B. et al. 2019, Fig. 6(b).jpg Ortiz-Sepulveda, C., Van Bocxlaer, B. et al. 2019, Fig. 6(c).jpg Ortiz-Sepulveda, C., Van Bocxlaer, B. et al. 2019, Fig. 6(d).jpg Ortiz-Sepulveda, C., Van Bocxlaer, B. et al. 2019, Fig. 6(e).jpg

12

return to couplet #11

  • Clypeus with its medial anterior portion forming a “lip” (Fig. 5(e1)); head and mesosoma partially or completely alveolate (sometimes alveolate-strigate); dorsum of the mesosoma with many erect hairs; body uniform in color => Brachymyrmex nebulosus
  • Clypeus without anteromedial “lip” (Fig. 5(e2)); entire body non-alveolate; dorsum of the mesosoma without erect hairs; head and gaster black;mesosoma yellowish => Brachymyrmex bicolor

Ortiz-Sepulveda, C., Van Bocxlaer, B. et al. 2019, Fig. 5(e).jpg

13

return to couplet #11

  • Head with strong alveolate sculpture => 14
  • Head without alveolate sculpture => 15

14

return to couplet #13

  • Metanotal groove wider than the diameter of the metathoracic spiracles (Fig. 6(f1): A ≤ B); scapes surpassing the posterior margin of the head by approximately 1.0× the maximal diameter of the eye (Fig. 5(d3)); gaster with scattered pubescence (Fig. 6(g1)) => Brachymyrmex santschii
  • Metanotal groove narrower than the diameter of the metathoracic spiracles (Fig. 6(f2): A > B); scapes just reaching the posterior margin of the head (Fig. 5(d2)); gaster with dense pubescence (Fig. 6(g2)) => Brachymyrmex iridescens

Ortiz-Sepulveda, C., Van Bocxlaer, B. et al. 2019, Fig. 6(f).jpg Ortiz-Sepulveda, C., Van Bocxlaer, B. et al. 2019, Fig. 6(g).jpg

15

return to couplet #13

  • Mesometanotal suture inconspicuous (Fig. 6(d1)) => 16
  • Mesometanotal suture readily visible (Fig. 6(d2)) => 17

Ortiz-Sepulveda, C., Van Bocxlaer, B. et al. 2019, Fig. 6(d).jpg

16

return to couplet #15

  • Pronotum without erect hairs; scapes short or reaching the posterior margin of the head (Fig. 5(d1, d2)); gaster with dense pubescence (Fig. 6(g2)) => Brachymyrmex flavidulus

Ortiz-Sepulveda, C., Van Bocxlaer, B. et al. 2019, Fig. 5(d).jpg Ortiz-Sepulveda, C., Van Bocxlaer, B. et al. 2019, Fig. 6(g).jpg

  • Pronotum with two erect hairs (Fig. 6(d1)); scapes surpassing the posterior margin of the head (Fig. 5(d3)); gaster without dense pubescence, but with scattered appressed hairs (Fig. 6(g1)) => Brachymyrmex minutus

Ortiz-Sepulveda, C., Van Bocxlaer, B. et al. 2019, Fig. 6(d).jpg Ortiz-Sepulveda, C., Van Bocxlaer, B. et al. 2019, Fig. 5(d).jpg Ortiz-Sepulveda, C., Van Bocxlaer, B. et al. 2019, Fig. 6(g).jpg

17

return to couplet #15

  • Gaster with dense appressed or decumbent pubescence (Fig. 6(g2)) => 18
  • Gaster with sparse pubescence, but with scattered, appressed hairs (Fig. 6(g1)) => 28

Ortiz-Sepulveda, C., Van Bocxlaer, B. et al. 2019, Fig. 6(g).jpg

18

return to couplet #17

  • Metanotal groove absent or when present shallow and narrower than the diameter of the metathoracic spiracles (Fig. 6(f2): A > B) => 19
  • Metanotal groove deep and wider than the diameter of the metathoracic spiracles (Fig. 6(f1): A ≤ B) => 26

Ortiz-Sepulveda, C., Van Bocxlaer, B. et al. 2019, Fig. 6(f).jpg

19

return to couplet #18

  • Mesonotumbulging dorsally above the pronotum in lateral view (Fig. 6(b1)) => 20
  • Mesonotum not bulging dorsally above the pronotum in lateral view (Fig. 6(b2)) => 22

Ortiz-Sepulveda, C., Van Bocxlaer, B. et al. 2019, Fig. 6(b).jpg

20

return to couplet #19

  • Scapes just reaching the posterior margin of the head or surpassing it by a length of less than 1.0× the maximal diameter of the eye (Fig. 5(d2,d3): A > B) => 21
  • Scapes surpassing the posterior margin of the head by a length of approximately 1.0× the maximal diameter of the eye (Fig. 5(d3): A ≈ B) => Brachymyrmex heeri

Ortiz-Sepulveda, C., Van Bocxlaer, B. et al. 2019, Fig. 5(d).jpg

21

return to couplet #20

  • Body usually dark brown; eye with on average nine ommatidia along its maximal diameter; scapes on average > 0.5 mm; known only from South America => Brachymyrmex giardi
  • Body yellowish; eye with on average six ommatidia along its maximal diameter; scapes on average < 0.5 mm; known only from Canada,Mexico, USA => Brachymyrmex depilis

22

return to couplet #19

  • Body yellowish => 23
  • Body dark brown => 25

23

return to couplet #22

  • Scapes not or barely reaching the posterior margin of the head (Fig. 5(d1, d2)) => Brachymyrmex fiebrigi
  • Scapes surpassing the posterior margin of the head (Fig. 5(d3)) => 24

Ortiz-Sepulveda, C., Van Bocxlaer, B. et al. 2019, Fig. 5(d).jpg

24

return to couplet #23

  • About six erect hairs on the pronotum and two on the mesonotum, each hair with a length of about 2.0× the maximal diameter of the eye; known only from the Bahamas => Brachymyrmex bahamensis
  • Two erect hairs on the pronotum and two on the mesonotum, each with a length shorter than the maximal diameter of the eye; widespread => Brachymyrmex termitophilus

25

return to couplet #22

  • Dorsum of the head and mesosoma with light-colored, dense pubescence; gaster with dense appressed pubescence; eye with on average 11 ommatidia along its maximal diameter, head on average long (HL1 > 0.5 mm) and wide (HW> 0.4 mm) => Brachymyrmex cordemoyi
  • Dorsum of the head and mesosoma with less conspicuous dense pubescence; gaster with dense decumbent pubescence; eye with on average nine ommatidia along its maximal diameter, head on average short (HL1 < 0.5 mm) and narrow (HW < 0.4 mm) => Brachymyrmex obscurior

26

return to couplet #18

  • Dorsum of the mesosoma without conspicuous sculpture; metathoracic spiracles fully dorsal in position; dorsal margin of the mesonotum strongly antero-posteriorly inclined (Fig. 6(e1)) => Brachymyrmex sosai
  • Dorsum of the mesosoma with imbricate sculpture; metathoracic spiracles in dorsolateral position; dorsal margin of the mesonotum not or slightly antero-posteriorly inclined (Fig. 6(e2)) => 27

Ortiz-Sepulveda, C., Van Bocxlaer, B. et al. 2019, Fig. 6(e).jpg

27

return to couplet #26

  • Second segment of the antennal funiculus shorter than the first antennal segment (Fig. 5(g1): S2 < S1); scapes with appressed hairs; metathoracic spiracles protruding slightly dorsally, but not tumiliform (Fig. 6(a3)); hairs lighter in color than the body, which is brownish => Brachymyrmex attenuatus
  • Second segment of the antennal funiculus as long or longer than the first antennal segment (Fig. 6(g2): S2 ≥ S1); scapes with decumbent hairs; methatoracic spiracles not protruding (Fig. 6(a2)) hairs darker in color than the body, which is yellowish => Brachymyrmex antennatus

Ortiz-Sepulveda, C., Van Bocxlaer, B. et al. 2019, Fig. 5(g).jpg Ortiz-Sepulveda, C., Van Bocxlaer, B. et al. 2019, Fig. 6(a).jpg Ortiz-Sepulveda, C., Van Bocxlaer, B. et al. 2019, Fig. 6(g).jpg

28

return to couplet #17

  • Eyes large, with a maximal diameter > 1/4th of the length of the head (HL1), usually with >14 ommatidia along their maximal diameter => Brachymyrmex oculatus
  • Eyes small, with a maximal diameter of approximately 1/4th the length of HL1, typically with <14 ommatidia along their maximal diameter => 29

29

return to couplet #28

  • Metanotal groove absent, or, when present, shallow and narrower than the diameter of the metathoracic spiracles (Fig. 6(f2): A > B) => 30
  • Metanotal groove deep and wider than the diameter of the metathoracic spiracles (Fig. 6(f1): A ≤ B.) => 34

Ortiz-Sepulveda, C., Van Bocxlaer, B. et al. 2019, Fig. 6(f).jpg

30

return to couplet #29

  • Head and thorax yellowish; gaster black or yellowish with a black spot, OI2 usually > 27 => Brachymyrmex pictus
  • Body of uniform color, OI2 usually < 25 => 31

31

return to couplet #30

  • Body yellowish, usually with a narrow mesonotum (MW ~ 16) and 8–9 ommatids along the maximum diameter of the eye => 32
  • Body brownish or dark brown, usually with a wide mesonotum (MW ~ 20 or more) and 10 or more ommatids along the maximum diameter of the eye => 33

32

return to couplet #31

  • Scapes surpassing the posterior margin of the head by a length exceeding the maximal diameter of the eye (Fig. 5(d3): A < B) => Brachymyrmex aphidicola
  • Scapes surpassing the posterior margin of the head by a length smaller than or equal to the maximal diameter of the eye (Fig. 5(d3): A ≥ B) => Brachymyrmex australis

Ortiz-Sepulveda, C., Van Bocxlaer, B. et al. 2019, Fig. 5(d).jpg

33

return to couplet #31

  • Scapes surpassing the posterior margin of the head by a length smaller than the maximal diameter of the eye (Fig. 5(d3): A > B); usually with two erect hairs on the pronotum and two on the mesonotum => Brachymyrmex patagonicus
  • Scapes surpassing the posterior margin of the head by a length approximately equal to the maximal diameter of the eye (Fig. 5(d3): A ≈ B); usually with more than two erect or decumbent hairs on the pronotum and two erect hairs on the mesonotum => Brachymyrmex bruchi

Ortiz-Sepulveda, C., Van Bocxlaer, B. et al. 2019, Fig. 5(d).jpg

34

return to couplet #29

  • Legs and antennae with erect hairs; second segment of the antennal funiculus as long as or longer than the first (Fig. 5(g2): S2 ≥ S1) => Brachymyrmex gaucho
  • Legs and antennae with decumbent or appressed hairs; second segment of the antennal funiculus shorter than the first(Fig. 5(g1): S2 < S1) => 35

Ortiz-Sepulveda, C., Van Bocxlaer, B. et al. 2019, Fig. 5(g).jpg

35

return to couplet #34

  • Mesonotum not bulging dorsally above the pronotum in lateral view (Fig. 6(b2)); metathoracic spiracles low, not protruding dorsally (Fig. 6(a2)) => Brachymyrmex musculus
  • Mesonotum bulging dorsally above the pronotum in lateral view (Fig. 6(b1)); metathoracic spiracles protruding slightly in lateral view but not tumiliform in shape (Fig. 6(a3)) => 36

Ortiz-Sepulveda, C., Van Bocxlaer, B. et al. 2019, Fig. 6(b).jpg Ortiz-Sepulveda, C., Van Bocxlaer, B. et al. 2019, Fig. 6(a).jpg

36

return to couplet #35

37

return to couplet #36

  • Head with dense decumbent pubescence (Fig. 5(f1)) => Brachymyrmex tristis
  • Head with sparse decumbent pubescence (Fig. 5(f2)) => 38

Ortiz-Sepulveda, C., Van Bocxlaer, B. et al. 2019, Fig. 5(f).jpg

38

return to couplet #37

  • Mesonotum laterally extended and therefore oval in dorsal view (Fig. 6(h1)); body light brown => Brachymyrmex degener
  • Mesonotum almost circular in dorsal view (Fig. 6(h2)); body dark brown or black => Brachymyrmex gagates

Ortiz-Sepulveda, C., Van Bocxlaer, B. et al. 2019, Fig. 6(h).jpg

39

return to couplet #1

  • Mesosoma mostly smooth and shiny, except for longitudinal striations restricted to the metapleura; body uniform light brown => Brachymyrmex micromegas
  • Mesosoma entirely covered with fine longitudinal striations; gaster darker than the rest of the body => Brachymyrmex pilipes

References

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