Key to North American Crematogaster species

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The following key to North American Crematogaster species has been modified from Morgan & Mackay (2017).

1

  • Postpetiole with two hemilobes, divided by longitudinal medial sulcus (look from above, Fig. 1 a; Plates 5 A and D); most common in temperate habitats => 2
Fig. 1
Plate 5
  • Postpetiole globular, not divided into two hemilobes by longitudinal medial sulcus (Fig. 1 b; Plates 5 B and C) or with slight emargination posteriorly (Fig. 1 c; Plate 5 E); most common in tropical and subtropical habitats => 25
Fig. 1
Fig. 1
Plate 5

2

return to couplet #1

  • Petiole approximately as wide as long, trapezoidal, obviously widened anteriorly (Fig. 2, left; Plate 5 A) => 3
Fig. 2
Plate 5
  • Petiole subrectangular, not greatly widened anteriorly, sides nearly parallel (Fig. 2, right; Plate 5 D), if somewhat quadrate, widest medially not anteriorly => 21
Fig. 2
Plate 5

3

return to couplet #2

  • Base of spines not connected at widest portion of propodeum (Fig. 3, left; Plate 4 E) => 4
Fig. 3
Plate 4
  • Base of spines connected at widest portion of propodeum (Fig. 3, right; Plates 4 A, B, C, D and F) => 5
Fig. 3
Plate 4

4

return to couplet #3

  • Head and mesosoma punctate-lineolate (Fig. 4. left), following curvature of head and pronotal shoulder; México (southern Chihuahua to Veracruz) => Crematogaster saussurei
Fig. 4

Crematogaster saussurei casent0902151 h 1 high.jpg Crematogaster saussurei casent0902151 p 1 high.jpg

Fig. 4

Crematogaster isolata casent0102832 head 1.jpg Crematogaster isolata casent0102832 profile 1.jpg

5

return to couplet #3

  • Spines reduced (length from posterior edge of propodeal spiracle to tip 0.16 mm or less, see Fig. 5, left; Plate 4 A) => 6
Fig. 5
Plate 4
  • Spines longer (length as above 0.17 mm or more, see Fig. 5, right; Plate 4 B and C) => 11
Fig. 5
Plate 4

6

return to couplet #5

  • Head shiny and glossy medially, side of pronotum shiny, partially or completely smooth (Fig. 6, left); propodeal spines tiny, length approximately as long as width at base of spines (less than 0.13 mm in length) => 7
Fig. 6
  • Head at least partially sculptured medially in part of series; side of pronotum shiny or sculptured, usually punctate (Fig. 6, right); spines often longer than 0.13 mm, not greatly widened at base of spines => 8
Fig. 6

7

return to couplet #6

  • Concolorous light to dark brown, rarely bicolored (Fig. 7, left); rarely nesting in pine trees; common and widely distributed in southern and SE USA, southern Mexico => Crematogaster ashmeadi
Fig. 7

Crematogaster ashmeadi casent0103761 head 1.jpg Crematogaster ashmeadi casent0103761 profile 1.jpg

  • Bicolored with head and mesosoma red and gaster dark (Fig. 7, right); nesting in pine trees in Florida and Tennessee => Crematogaster pinicola
Fig. 7

Crematogaster pinicola casent0172943 head 1.jpg Crematogaster pinicola casent0172943 profile 1.jpg

8

return to couplet #6

  • Dorsum of head completely or nearly completely punctate (Fig. 8, left); mesosoma densely punctate; southern Arizona to southern México => Crematogaster opaca
Fig. 8

Crematogaster opaca casent0104692 head 1.jpg Crematogaster opaca casent0104692 profile 1.jpg

  • Dorsum of head partially smooth and glossy (Fig. 8, right); mesosoma rugose or shallowly costate; widely distributed => 9
Fig. 8

9

return to couplet #8

  • Medial mesonotal carina sharp and raised from surface (Fig. 9, left); side of pronotum mostly smooth and glossy; southeastern Texas and eastern México => Crematogaster rifelna
Fig. 9

Crematogaster rifelna casent0103516 head 1.jpg Crematogaster rifelna casent0103516 profile 1.jpg

  • Medial mesonotal carina poorly developed, barely raised from surface (Fig. 9, right); side of pronotum may be shiny, but is usually completely or nearly completely sculptured; widely distributed => 10
Fig. 9

10

return to couplet #9

  • Dorsal edge of propodeal spine sinuous (curved somewhat upwards distally) (Plate 4 B, Fig. 10); common in entire USA, northern Mexico => Crematogaster cerasi
Fig. 10
Plate 4

Crematogaster cerasi casent0103776 head 1.jpg Crematogaster cerasi casent0103776 profile 1.jpg

  • Dorsal edge of propodeal spine straight (Fig. 9, right); southwestern USA and NW México => Crematogaster emeryana
Fig. 9

Crematogaster emeryana casent0102831 head 1.jpg Crematogaster emeryana casent0102831 profile 1.jpg

11

return to couplet #6

  • Majority of specimens in series with 4 or fewer erect hairs on each pronotal shoulder (larger workers often have more hairs) (Fig. 11, left); mostly western USA and México => 12
Fig. 11
  • Pronotal shoulder of majority of workers with 5 or more erect hairs (Fig. 11, right); mostly eastern USA and eastern México => 17
Fig. 11

12

return to couplet #11

  • Side of pronotum shiny (Fig. 11, left); strongly bicolored (gaster black, remainder red, see Fig. 7, right); entire southern USA, eastern USA and México => Crematogaster laeviuscula
Fig. 11
Fig. 7

Crematogaster laeviuscula casent0104828 head 1.jpg Crematogaster laeviuscula casent0104828 profile 1.jpg

  • Lateropronotum heavily sculptured (Fig. 11, right, Fig. 12); concolorous to slightly bicolored (see Fig. 7, left) => 13
Fig. 11
Fig. 12
Fig. 7

13

return to couplet #12

  • Pronotal shoulder with 1 to 4 erect hairs (Fig. 12, left) in majority of specimens in series => 14
Fig. 12
  • Pronotal shoulders completely without erect hairs (Fig. 12, right) in all specimens in series; SW USA, México => Crematogaster depilis
Fig. 12

Crematogaster depilis casent0005668 head 1.jpg Crematogaster depilis casent0005668 profile 1.jpg

14

return to couplet #13

  • Each posterior corner of petiole with small tooth (Fig. 13; Plate 25 B); southern and eastern USA to central México => Crematogaster dentinodis
Fig. 13
Morgan & Mackay (2017) Plate 25.jpg

Crematogaster dentinodis casent0102830 head 1.jpg Crematogaster dentinodis casent0102830 profile 1.jpg

  • Posterior corners of petiole without teeth; widely distributed => 15

15

return to couplet #14

Fig. 14

Crematogaster vermiculata casent0103810 head 1.jpg Crematogaster vermiculata casent0103810 profile 1.jpg

  • Pronotum shoulder with longitudinal rugae (Fig. 14, right); widely distributed => 16
Fig. 14

16

return to couplet #15

  • Mesosoma of queen wider than head (Plate 17 A and B); common and widely distributed from western USA to southern México => Crematogaster coarctata
Fig. 17

Crematogaster coarctata casent0005667 head 1.jpg Crematogaster coarctata casent0005667 profile 1.jpg

  • Mesosoma of queen narrower than head (Plate 54 A and B); rarely collected, Utah west to southern California, south to southern México => Crematogaster mutans
Plate 54

Crematogaster mutans casent0005672 head 1.jpg Crematogaster mutans casent0005672 profile 1.jpg

17

return to couplet #11

  • Dorsum of head with more than 10 erect hairs, dorsum of mesosoma with more than 15 erect hairs (Fig. 15 right) => 18
Fig. 15
  • Dorsum of head usually with fewer than 10 erect hairs, dorsum of mesosoma usually with fewer than 15 (up to 20 may be present) short bristle-like erect hairs (Fig. 15, left); California east to SE Canada S to Florida and northern Mexico => Crematogaster lineolata
Fig. 15

Crematogaster lineolata casent0103781 head 1.jpg Crematogaster lineolata casent0103781 profile 1.jpg

18

return to couplet #17

  • Most of dorsum of head smooth and glossy, surrounding area finely striolate or areolate (Fig. 16 and 17) => 19
Fig. 16
Fig. 17
  • Dorsum of head nearly completely punctate (see Fig. 8, left), medial area may be glossy => 20
Fig. 8

19

return to couplet #18

  • Most hairs on pronotal shoulder relatively short (less than 0.15 mm) (Fig. 16); Texas northeast to New Jersey, south to Florida => Crematogaster pilosa
Fig. 16

Crematogaster pilosa casent0103806 head 1.jpg Crematogaster pilosa casent0103806 profile 1.jpg

  • Most hairs on pronotal shoulder relatively long (over 0.18 mm in length) (Fig. 15, right); Nevada, Colorado, Arizona and New Mexico => Crematogaster navajoa
Fig. 15

Crematogaster navajoa casent0064826 head 1.jpg Crematogaster navajoa casent0064826 profile 1.jpg

20

return to couplet #18

  • Longitudinal carina well developed in center of pronotum; southern half of the US south to central México => Crematogaster punctulata

MCZ-ENT00586646 Crematogaster punctulata hef.jpg MCZ-ENT00586646 Crematogaster punctulata hal.jpg

  • Longitudinal carina poorly developed on center of pronotum; eastern and central México => Crematogaster patei

Crematogaster patei head.jpg Crematogaster patei side.jpg

21

return to couplet #2

  • Dorsum of head (face) partially smooth and glossy (Fig. 18, left); México south to Argentina => Crematogaster distans
Fig. 18

Crematogaster distans casent0103431 head 1.jpg Crematogaster distans casent0103431 profile 1.jpg

  • Dorsum of head predominantly or completely and densely punctate or vermiculate, dull (Fig. 18, right) => 22
Fig. 18

22

return to couplet #21

  • Propodeal spines nearly as long or longer than width of petiole (Fig. 19, left); México to Brazil => 23
Fig. 19
  • Propodeal spine length much less than ½ width of petiole (Fig. 19, right); southern Texas to Costa Rica => 24
Fig. 19

23

return to couplet #22

  • Dorsum of head and pronotum densely punctate (Fig. 20, left); México and Guatemala => Crematogaster formosa
Fig. 20

Crematogaster formosa casent0193615 h 1 high.jpg Crematogaster formosa casent0193615 p 1 high.jpg

  • Dorsum of head and pronotum roughly rugose punctate or vermiculate punctate (Fig. 20, right); southern México south to Brazil => Crematogaster acuta
Fig. 20

Crematogaster acuta casent0173927 head 1.jpg Crematogaster acuta casent0173927 profile 1.jpg|350px]]

24

return to couplet #22

  • Petiole elongate, almost 2X as long as wide (dorsal view), sides nearly parallel and straight (Fig. 2, right); propodeal spines reduced to tiny, sharp tooth; eastern and southern México to Brazil => Crematogaster montezumia
Fig. 2

Crematogaster montezumia casent0173939 head 1.jpg Crematogaster montezumia casent0173939 profile 1.jpg

  • Petiole subquadrate, slightly wider than long, widest medially (Fig. 19, right); propodeal spines well developed but small (length about 2X diameter of propodeal spiracle); southern USA (southern tip of Texas) to Costa Rica => Crematogaster corvina
Fig. 19

Crematogaster corvina casent0193759 h 1 high.jpg Crematogaster corvina casent0193759 p 1 high.jpg

25

return to couplet #1

  • Petiole slender, 1.5-2 times as long as wide, slightly wider posteriorly, as seen from above (Fig. 21, left) => 26
Fig. 21
  • Petiole subquadrate (Fig. 21, right) => 29
Fig. 21

26

return to couplet #25

  • Dorsum of pronotum, including medial area, with several varicose or reticulate longitudinal carinae, which strongly contrast against smooth and shiny background (Fig. 22, left) => 27
Fig. 22
  • Dorsum of pronotum shiny, without carinulae at least medially, but carinulae may be present along edges (Fig. 22, right) => 28
Fig. 22

27

return to couplet #26

  • Propodeal spines very long, longer than length of distance between bases (measured from posterior edge of propodeal spiracle, seen from above), extending to near posterior edge of petiole (when petiole is in same plane as mesosoma) (see Fig. 23), diverging as seen from above; pronotum with long (longer than greatest eye diameter) dark brown or bronze colored hairs; southern Mexico south to Bolivia => Crematogaster nigropilosa
Fig. 23
Fig. 23

Crematogaster nigropilosa casent0173945 head 1.jpg Crematogaster nigropilosa casent0173945 profile 1.jpg

  • Propodeal spines about as long as distance between bases when measure as above, slightly incurved (Fig. 22, left); pronotum with shorter (most about greatest eye diameter) silver or white hairs; Florida and México to Brazil => Crematogaster curvispinosa
Fig. 22

Crematogaster curvispinosa casent0173308 head 1.jpg Crematogaster curvispinosa casent0173308 profile 1.jpg

28

return to couplet #26

  • Clypeus completely smooth and glossy, occasionally with poorly developed longitudinal carinulae; hairs on pronotum dark brown; posterior edge of mesonotum with small angle (Fig. 23, left); USA (southern Arizona) to Bolivia => Crematogaster sotobosque
Fig. 23

Crematogaster sotobosque inbiocri001237410 h 1 high.jpg Crematogaster sotobosque inbiocri001237410 p 1 high.jpg

  • Clypeus usually with moderately well-defined longitudinal carinulae; hairs on pronotum whitish; mesonotum without small angle (Fig. 23, right); México to Brazil => Crematogaster limata
Fig. 23

Crematogaster limata casent0912774 h 1 high.jpg Crematogaster limata casent0912774 p 1 high.jpg

29

return to couplet #25

  • Dark brown (Fig. 24, left) => 30
Fig. 24
  • Yellow or pale brown (Fig. 24, right) => 34
Fig. 24

30

return to couplet #29

  • Lateropronotum mostly or entirely covered by horizontal striolae, usually mixed with punctures, weakly to moderately shining (Fig. 25, left); rarely collected, central México to Argentina => Crematogaster atra
Fig. 25

Crematogaster atra jtl055858 h 1 high.jpg Crematogaster atra jtl055858 p 1 high.jpg

  • Lateropronotum predominantly smooth and glossy, strongly shining (Fig. 25, right); common and widely distributed => 31
Fig. 25

31

return to couplet #30

  • Most of clypeus (at least medial area) smooth and glossy (Fig. 26, left); southern Texas, Louisiana and southern Florida south to Venezuela => Crematogaster obscurata
Fig. 26

Crematogaster obscurata casent0103800 head 1.jpg Crematogaster obscurata casent0103800 profile 1.jpg

  • Clypeus covered with fine longitudinal striae (medial area may be slightly smooth and shining) (Fig. 26, right); widely distributed => 32
Fig. 26

32

return to couplet #31

  • Sternopetiolar process absent to poorly developed (Fig. 27, left); SW USA to Brazil => Crematogaster torosa
Fig. 27

Crematogaster torosa casent0102828 head 1.jpg Crematogaster torosa casent0102828 profile 1.jpg

  • Sternopetiolar process well developed (Fig. 27, middle); widely distributed including SW USA and México => 33
Fig. 27

33

return to couplet #32

  • Gaster sparsely evenly covered with short erect hairs (Fig. 28, left); sternopetiolar process small (Fig. 27, middle); SW USA to Argentina => Crematogaster crinosa
Fig. 28
Fig. 27

Crematogaster crinosa casent0173935 head 1.jpg Crematogaster crinosa casent0173935 profile 1.jpg

  • Gaster without erect hairs except along lateral margins (Fig. 28, right); sternopetiolar process well developed (Fig. 27, right); México south to Brazil => Crematogaster rochai
Fig. 28
Fig. 27

Crematogaster rochai casent0173946 head 1.jpg Crematogaster rochai casent0173946 profile 1.jpg

34

return to couplet #29

  • Erect hairs on pronotum very long, usually at least one hair longer than twice greatest eye diameter (Fig. 29. left); México to Argentina => Crematogaster sumichrasti
Fig. 29

Crematogaster sumichrasti casent0603544 head 1.jpg Crematogaster sumichrasti casent0603544 profile 1.jpg

  • Erect hairs on pronotum shorter than 1.5 times maximum eye diameter (Fig. 29, right); United States to Costa Rica => 35
Fig. 29

35

return to couplet #34

  • Propodeal spines relatively long (Fig. 30, left) as seen from above, length (measured from posterior edge of propodeal spiracle to tip) about ½ length of distance between bases (seen obliquely from above), and slightly bent upwards; carinulae on pronotal dorsum mostly on sides; middle and eastern USA to southern México; possibly Cuba => Crematogaster missouriensis
Fig. 30

MCZ-ENT00020816 Crematogaster missuriensis syntype head.jpg MCZ-ENT00020816 Crematogaster missuriensis syntype side.jpg

  • Propodeal spines relatively short (Fig. 30, right), length less than ⅓ distance between bases, and not noticeably bent upwards; carinulae on pronotal dorsum also found in central region; S and SE USA to Costa Rica => Crematogaster minutissima
Fig. 30

Crematogaster minutissima casent0103789 head 1.jpg Crematogaster minutissima casent0103789 profile 1.jpg

References