Key to the Ant Genera of New Mexico

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
 * Antennae with 6 segments; unknown from New Mexico . . . . . Strumigenys louisianae
 * Antennae with more than 6 segments . . . . . 12

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
 * Antenna consisting of 10 or 11 segments . . . . . 14
 * Antenna consisting of 12 segments . . . . . 21

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
 * Pronotum with bumps or spines . . . . . 17
 * Pronotum without bumps or spines . . . . . 20

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
 * Petiole and postpetiole with lateral spines; unknown from NM . . . . . Cephalotes rohweri
 * Petiole and postpetiole without lateral spines . . . . . 19

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
 * Clypeus strongly projecting or overhanging above mandibles . . . . . Cardiocondyla ectopia
 * Clypeus not strongly projecting above mandibles . . . . . Temnothorax pergandei

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