Key to Ant Genera of the Navajo Reservation

This key to workers is based on Mackay and Mackay. 2002. The Ants of New Mexico: Hymenoptera:Formicidae. The Edwin Mellon Press. Lewiston, N.Y.; A Field Guide to the Ants of New England, and Ants of North America (A Guide to the Genera). At present 24 ant genera are known within the Navajo Reservation, as additional ant genera are discovered, they will be added to the key below.

1

 * Petiole and postpetiole present (pedicel has two segments) . . . . . 2


 * Petiole present (pedicel has one segment), postpetiole absent or not well separated from remainder of gaster . . . . . 3

2
return to couplet #1
 * Frontal carinae positioned close to each other and do not cover insertions of antennae, which are located near base of mandibles. Eyes absent or extremely small (Subfamily Ecitoninae) . . . . . Neivamyrmex (2 species)
 * Frontal carinae not positioned near each other and with lobes which partially or completely cover insertions of antennae (Subfamily Myrmicinae) . . . . . 5

3
return to couplet #2


 * No postpetiole, petiole clearly separated from remainder of gaster; sting absent. . . . . . 4


 * Postpetiole with a slight separation from remainder of gaster; sting present; Subpetiolar process simple lobe, never with fenestra or paired posterolateral teeth. Anterior border of clypeus without teeth; mandible relatively small (Subfamily Ponerinae). . . . . Hypoponera opacior (1 species)

4
return to couplet #3
 * Acidopore absent, no ring of hairs at apex of gaster (Subfamily Dolichoderinae) . . . . . 22


 * Acidopore at apex of gaster round and usually surrounded by ring of hairs (Subfamily Formicinae) . . . . . 37

5
return to couplet #2
 * 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 . . . . . 6

6
return to couplet #12
 * Antenna consisting of 11 segments . . . . . 7


 * Antenna consisting of 12 segments . . . . . 21

7
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

File:MCZ-ENT00671965 Crematogaster larreae hal.jpg


 * Postpetiole not connected to upper surface of gaster; gaster not heart shaped . . . . . 8

8
return to couplet #16
 * Frontal carina extends to posterior border of head; dark red or grayish black ants; monomorphic . . . . . 18


 * Petiole and postpetiole without lateral spines . . . . . 19

10
return to couplet #16


 * Clypeus not forming welt; frontal carinae do not extend to posterior border of head . . . . . Leptothorax

11
return to couplet #21


 * Clypeus not elevated in form of welt . . . . . 23

12
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

13
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; psammophore absent; common in pine forests and mountainous areas . . . . . 25

14
return to couplet #24
 * Propodeum with spines or teeth . . . . . Myrmica

15
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

16
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

17
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

18
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)

19
return to couplet #29


 * Eyes with more than 50 ommatidia; antennal club shorter than remainder of funiculus . . . . . 31

20
return to couplet #30


 * Clypeus not strongly projecting above mandibles . . . . . Temnothorax pergandei

21
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

22
return to couplet #4
 * Propodeum in form of cone; maxillary palps very long . . . . . Dorymyrmex


 * Propodeum never in form of cone . . . . . 34

23
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 . . . . . 44

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

44
return to couplet #42
 * Maxillary palps short and composed of 3 segments, difficult to see . . . . . Acanthomyops


 * Maxillary palps longer and composed o f 6 segments, very obvious . . . . . Lasius