Key to the Ant Genera of New Mexico

AntWiki: The Ants --- Online

This key is based on Mackay and Mackay. 2002. The Ants of New Mexico: Hymenoptera:Formicidae. The Edwin Mellon Press. Lewiston, N.Y.

1

  • Petiole and postpetiole present . . . . . 2
  • Petiole present, but postpetiole not well separated from remainder of gaster . . . . . 4

2

return to couplet #1

  • Frontal carinae (singular carina) positioned close to each other and do not cover insertions of antennae, which are located near base of mandibles . . . . . 3
  • Frontal carinae not positioned near each other and with lobes which partially or completely cover insertions of antennae (Subfamily Myrmicinae) . . . . . 11

3

return to couplet #2

  • Eyes very large, covering large portion of head; 3 ocelli usually present; body long, slender (Subfamily Pseudomyrmecinae) . . . . . Pseudomyrmex
  • Eyes absent or extremely small (Subfamily Ecitoninae) . . . . . Neivamyrmex

4

return to couplet #1

  • Mandibles very long with 3 teeth at apex, or constriction present between postpetiole and remainder of gaster; or; integument hard; sting well developed; uncommon . . . . . 5
  • No (or slight) constriction between postpetiole and remainder of gaster; mandibles never elongate; integument soft; sting absent or rudimentary; very common ants . . . . . 10

5

return to couplet #4

  • Mandibles elongate (Fig. 18) with 3 teeth at apex; antennae with 12 segments; petiole sharply pointed above; gaster with very weak constriction between first 2 terga . . . . . Odontomachus
  • Mandibles not elongated gaster with well-developed constriction between first 2 terga . . . . . 6

6

return to couplet #5"

  • Antennae with 11 segments, last one forming club whose length is approximately as long as preceding 4 segments; 3 ocelli present; rarely collected . . . . . Cerapachys
  • Antennae with 12 segments, the last one not forming a club; ocelli usually absent . . . . . 7

7

return to couplet #6

  • Eyes absent or extremely small; pygidium (dorsum of last segment of gaster) bordered laterally by small spines. . . . . Acanthostichus punctiscapus
  • Eyes nonnally present and often large; pygidium not bordered laterally by small spines . . . . . 8

8

return to couplet #7

  • Subpetiolar process with blunted, angled anteroventral corner and 2 distinctly angular posteroventral acute teeth, situated side by side; anteriorly the subpetiolar process has circular or oval "thin spot" or fenestra, visible in transmitted light . . . . . Ponera pennsylvanica
  • Subpetiolar process simple lobe, never with fenestra or paired posterolateral teeth . . . . . 9

9

return to couplet #8

  • Anterior border of clypeus with teeth; mandibles large with irregular, paired teeth . . . . . Stigmatomma pallipes
  • Anterior border of clypeus without teeth; mandible relatively small . . . . . Hypoponera

10

return to couplet #4

  • Acidopore absent, no ring of hairs at apex of gaster (Subfamily Dolichoderinae) . . . . . 33
  • Acidopore at apex of gaster round and usually surrounded by ring of hairs (Subfamily Formicinae) . . . . . 37

11

return to couplet #2

12

return to couplet #11

  • Antennae with 10 segments, last 2 forming club; propodeum without spines; either dimorphic species or very small monomorphic species . . . . . Solenopsis
  • Antennae with 11 or 12 segments, if only 10 segments present, antennal club formed from last 3 segments . . . . . 13

13

return to couplet #12

14

return to couplet #13

  • Antenna with 3 segmented club; propodeum without spines; mesosoma mostly smooth, shining . . . . . Tranopelta
  • Antenna with or without 3 segmented club; propodeum with spines or teeth; mesosoma not smooth and shining . . . . . 15

15

return to couplet #14

  • Postpetiole connected to dorsal surface of gaster; gaster, when seen from above, heart shaped with pointed apex; pronotum without spines or bumps . . . . . Crematogaster
  • Postpetiole not connected to upper surface of gaster; gaster not heart shaped . . . . . 16

16

return to couplet #15

17

return to couplet #16

  • Frontal carina extends to posterior border of head; dark red or grayish black ants; monomorphic . . . . . 18
  • Frontal carina does not extend more than 1/2 distance from posterior border of clypeus to posterior border of head; polymorphic red ants (2 - 6 mm) . . . . . Acromyrmex versicolor

18

return to couplet #17

19

return to couplet #18

  • Dorsum of mesosoma with distinct pointed spines; greater than 3 mm in total length . . . . . Trachymyrmex
  • Dorsum of mesosoma with bumps; less than 3 mm in total length . . . . . Cyphomyrmex

20

return to couplet #16

  • Clypeus elevated and forming welt (sharp-edged carina) in front of antennal insertions; frontal carinae extend to posterior border of head and form scrobes to receive antennae . . . . . Tetramorium (in part)
  • Clypeus not forming welt; frontal carinae do not extend to posterior border of head . . . . . Leptothorax

21

return to couplet #13

  • Propodeum with 2 pairs of spines; petiole with short peduncle; legs short, femora and tibiae thickened; rarely collected . . . . . Myrmecina americana
  • Without all of these characteristics; commonly collected . . . . . 22

22

return to couplet #21

  • Clypeus elevated and forming welt in front of antennal insertions . . . . . Tetramorium (in part)
  • Clypeus not elevated in form of welt . . . . . 23

23

return to couplet #22

  • Middle and hind tibial spurs pectinate (with tiny hairs, Fig. 40, difficult to see without high magnification) . . . . . 24
  • Middle and hind tibial spurs not pectinate . . . . . 26

24

return to couplet #23

  • Metanotal constriction (between mesonotum and propodeum) absent, propodeum often with spines, psammophore (long curved hairs on underside of head) usually present (Fig. 41); common in arid ecosystems . . . . . Pogonomyrmex
  • Metanotal constriction present between mesonotum and propodeum (Fig. 42), which usually has spines (absent in Manica); psammophore absent; common in pine forests and mountainous areas . . . . . 25

25

return to couplet #24

  • Propodeum with spines or teeth . . . . . Myrmica
  • Propodeum without spines or teeth, although blunt protuberances may be present . . . . . Manica invidia

26

return to couplet #23

  • Propodeum without spines; antennal club composed of 3 segments; usually small, shiny, black ants . . . . . Monomorium
  • Propodeum with spines, or if not, ants not small, shiny and black; antennal club configuration varies . . . . . 27

27

return to couplet #26

  • Antennal club composed of 3 segments (1 rare species, Pheidole clydei, with 4- segmented club) . . . . . 28
  • Antenna without club or club with more than 3 segments . . . . . 32

28

return to couplet #27

  • Workers dimorphic or polymorphic; major with head longer than gaster; petiole with long peduncle; scape of antenna of minor often extends past posterior border of head; mandible with 2 well defined teeth at apex (47); very common ants . . . . . Pheidole
  • Monomorphic species; scape does not extend past posterior lateral border of head . . . . . 29

29

return to couplet #28

  • Peduncle of petiole about as long as height of petiolar node; mesosoma moderately to strongly arched; promesonotal and metanotal suture often faintly indicated or absent; extremely rare, in arid and semiarid regions . . . . . 30
  • Peduncle generally much shorter than height of node of petiole; mesosoma usually with flat dorsum; common, especially in pine forests, but occurring in all habitats . . . . . Leptothorax (and Formicoxenus short hairs present between the facets of the compound eye)

30

return to couplet #29

  • Eyes with fewer than 50 ommatidia; antennal club longer than remainder of funiculus; anteroinferior pronotal angle present . . . . . Rogeria
  • Eyes with more than 50 ommatidia; antennal club shorter than remainder of funiculus . . . . . 31

31

return to couplet #30

32

return to couplet #27

  • Clypeus usually with pair of longitudinal carinae; mesosoma thickened with little constriction between mesonotum and propodeum; rarely collected ants . . . . . Stenamma
  • Clypeus without carinae or with more than 1 pair; mesosoma slender; common ants in numerous habitats . . . . . Aphaenogaster

33

return to couplet #10

  • Propodeum in form of cone; maxillary palps very long . . . . . Dorymyrmex
  • Propodeum never in form of cone . . . . . 34

34

return to couplet #33

  • Node of petiole poorly developed; monomorphic ants, widely distributed in mesic areas of state . . . . . Tapinoma sessile
  • Node of petiole obvious, although it may be small; common ants . . . . . 35

35

return to couplet #34

  • Workers polymorphic; mesosoma in profile without impression before posterior edge of propodeum; ocelli present at least in larger workers; gaster with gray pubescence; nests usually in oak trees or under stones in mountainous areas . . . . . Liometopum
  • Workers monomorphic; ocelli absent; nesting in soil . . . . . 36

36

return to couplet #35

  • Erect hairs on clypeus long, extending to near tips of mandibles, when mandibles are shut; pronotum with at least I pair of long, erect hairs (may be missing in some specimens in nest series); most common in desert regions (also common in urban areas) . . . . . Forelius
  • Erect hairs on clypeus short, not extending to near tips of mandibles; pronotum without long, erect hairs; rarely collected in New Mexico, occurring in mesic and urban areas . . . . . Linepithema humile

37

return to couplet #10

  • Antenna with 9 segments; small, light colored, inconspicuous ants, not commonly collected . . . . . Brachymyrmex depilis
  • Antenna with more than 9 segments; common ants . . . . . 38

38

return to couplet #37

  • Mandibles long, sickle shaped; red ants, not commonly collected . . . . . Polyergus
  • Mandibles not long and sickle shaped, common ants . . . . . 39

39

return to couplet #38

  • Insertions of antennae located far from posterior border of clypeus; mesosoma convex (except for C. hyatti) in profile . . . . . Camponotus
  • Insertions of antennae located near posterior border of clypeus; mesosoma not convex in profile . . . . . 40

40

return to couplet #39

  • Maxillary palps very long, segment 4 as long as segments 5 and 6 combined; psammophore present . . . . . Myrmecocystus
  • Maxillary palps shorter, segment 4 not unusually long; psammophore absent . . . . . 41

41

return to couplet #40

  • Frontal carinae prominent, lateral margins slightly reflected upward; ocelli often distinct; mostly large, polymorphic . . . . . Formica
  • Frontal carinae poorly marked, lateral margins flat; ocelli indistinct or absent; smaller monomorphic ants . . . . . 42

42

return to couplet #41

  • Antennal scapes surpassing posterior margin of head by at least 1/[?] their length, often much longer; erect hairs often coarse, long and usually black in color and are especially noticeable on dorsum of pronotum . . . . . 43
  • Antennal scapes not surpassing posterior lateral margin, or at least not by amount greater than length of first funicular segment; erect hairs not coarse, are short and golden . . . . . Lasius

43

return to couplet #42

  • Mesosoma (seen from above) with mesonotum strongly compressed or narrowed, swollen in front and behind constriction; scapes and tibiae without erect hairs; most or all of eye posterior to middle of head; generally larger ants (most workers nearly 4 mm in total length) . . . . . Prenolepis imparis
  • Mesosoma (from above) only slightly constricted at mesonotum; scapes and tibiae usually with erect hairs; most or all of eyes at or anterior to middle of head; generally smaller ants (most workers less than 3 mm total length) . . . . . Paratrechina
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