Identification key to Brachymyrmex species

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
 * Clypeus with a row of long thick hairs near the anterior margin (Fig. 5(a2)), remaining pilosity not as above; dimorphic

2

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

3

 * Toruli surpassing the posterior clypeal margin in oblique anterodorsal view (Fig. 5(a3)); head and mesosoma smooth and shiny
 * 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

4

 * 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

 * 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

 * 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))
 * 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))

7

 * Mesonotum not bulging dorsally above the pronotum in lateral view (Fig. 6(b1))
 * Mesonotum bulging dorsally above the pronotum in lateral view (Fig. 6(b2)) Brachymyrmex modestus

8

 * 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

9

 * Two erect hairs between the metathoracic spiracles
 * Without erect hairs between the metathoracic spiracles

10

 * 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

11

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

12

 * 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

13

 * Head with strong alveolate sculpture
 * Head without alveolate sculpture

14

 * 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

15

 * Mesometanotal suture inconspicuous (Fig. 6(d1))
 * Mesometanotal suture readily visible (Fig. 6(d2))

16

 * 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
 * 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

17

 * Gaster with dense appressed or decumbent pubescence (Fig. 6(g2))
 * Gaster with sparse pubescence, but with scattered, appressed hairs (Fig. 6(g1))

18

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

19

 * Mesonotumbulging dorsally above the pronotum in lateral view (Fig. 6(b1))
 * Mesonotum not bulging dorsally above the pronotum in lateral view (Fig. 6(b2))

20

 * 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)
 * 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

21

 * 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

 * Body yellowish
 * Body dark brown

23

 * 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

 * 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

 * 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

 * 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

 * 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

28

 * 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

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

30

 * 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

 * Body yellowish, usually with a narrow mesonotum (MW ~ 16) and 8–9 ommatids along the maximum diameter of the eye
 * 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

32

 * 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

33

 * 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

34

 * 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

 * 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

 * Head and thorax yellow or brown, gaster darker Brachymyrmex coactus
 * Body uniform in color

37

 * Head with dense decumbent pubescence (Fig. 5(f1)) Brachymyrmex tristis
 * Head with sparse decumbent pubescence (Fig. 5(f2))

38

 * 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

39

 * 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