Key to Pheidole flavens group

Key to Pheidole flavens group

This worker key is based on:

These species, the great majority of which are instantly recognizable by their small size, vestigial or absent mesonotal convexity, and short, 12-segmented antennae, compose the most speciose and numerically abundant group of the New World Pheidole. Found variously from North Carolina to Argentina, the species collectively are also, with the fallax group, the most widely distributed of the Pheidole groups. One species, Pheidole darlingtoni, is known only from the minor worker and is not included in the key that follows. An apparent endemic of Haiti, it is readily distinguished by its rugoreticulate clypeus and strikingly bicolorous head (whitish yellow and light brown).

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 * Pheidole
 * "New World Pheidole" Wilson 2003

1

 * Major: seen in full-face view, rugoreticulum present on occiput, or at least the occipital lobes, or in bands or patches directly in front of the occipital lobes, or elsewhere on the posterior fifth of the dorsal surface of the head . . . . . 2


 * Major: seen in full-face view, no rugoreticulum present on or near the occiput or anywhere on the posterior fifth of the dorsal surface of the head . . . . . 30

2
return to couplet #1
 * Major: in full-face view, entire occiput, including the occipital lobes and the dorsal surface of the head between them, is covered by rugoreticulum . . . . . 3


 * Major: in full-face view, at least a posteriormost strip of the occiput, or at least a narrow space along the occiput at the midline, or both, is free of rugoreticulum . . . . . 18

3
return to couplet #2
 * Major: in full-face view, all of the head behind the level of the posterior margin of the eyes rugoreticulate . . . . . 4


 * Major: in full-face view, a substantial space posterior to the eyes or to the frontal lobes, or to both, carinulate but not rugoreticulate . . . . . 5

4
return to couplet #3
 * Major: in side view, space immediately laterad to eye is rugoreticulate. Minor: posterior half of head rugoreticulate (Costa Rica, Honduras) . . . . . Pheidole verricula


 * Major: in side view, space immediately laterad to eye is carinulate, not rugoreticulate. Minor: posterior half of head foveolate, not rugoreticulate (Argentina, Uruguay) . . . . . Pheidole obtusopilosa

5
return to couplet #3
 * Major: anterior third of pronotal dorsum entirely rugoreticulate; mesonotum longitudinally carinulate (Costa Rica) . . . . . Pheidole renae


 * Major: with possible exception of edges of humeri, anterior third of pronotal dorsum variously transversely carinulate, foveolate or smooth, but not rugoreticulate; mesonotum foveolate or smooth, not carinulate . . . . . 6

6
return to couplet #5
 * Major: pronotal dorsum, with the possible exception of the edges of the humeri, entirely smooth and shiny, and lacking carinulae . . . . . 7


 * Major: pronotal dorsum at least partly foveolate, and opaque to feebly shiny, often with transverse carinulae in addition . . . . . 8

7
return to couplet #6
 * Major: seen from above, the pronotal humeri form obtuse angles, with several short rugulae on the apices; in full-face view, the rugoreticulum covers the occipital lobes, but just barely extends to the midline of the head capsule, as well as along the sides of the head (Bolivia) . . . . . Pheidole infernalis


 * Major: seen from above, the pronotal humeri are evenly rounded, with no sculpturing of any kind on the apices; in full-face view, the rugoreticulum covers the entire posterior fourth of the head capsule (Honduras) . . . . . Pheidole ceibana

8
return to couplet #6
 * Major: pronotal dorsum entirely covered by (sometimes faint) transverse carinulae . . . . . 9


 * Major: carinulae absent from pronotal dorsum or at most limited to its anterior or lateral margins . . . . . 10

9
return to couplet #8
 * Major: seen in dorsal-oblique view (mesosoma rotated around long axis 45 degrees from top view), profile of pronotal humerus forms a blunt obtuse angle; in side view posterior ventral quarter of head capsule is smooth and shiny. Minor: seen from above and obliquely, humeri bear acute-angular spines, each with a long hair emerging from its apex (Honduras) . . . . . Pheidole floricola


 * Major: seen in dorsal-oblique view, profile of humerus is smoothly rounded, in side view posterior ventral quarter of head capsule varies from foveolate and opaque to somewhat shiny. Minor: seen from above and obliquely, humerus bears low, inconspicuous convexities, which lack apical hairs (southern Brazil, Argentina, Paraguay) . . . . . Pheidole lignicola

10
return to couplet #8
 * Major: length of eye as great as the distance between the anterior margin of the eye to the front margin of the head capsule directly anterior to it . . . . . 11


 * Major: length of eye much less than the distance between the anterior margin of the eye and front margin of the head . . . . . 12

11
return to couplet #10
 * Major: seen in dorsal-oblique view (mesosoma rotated around long axis 45 degrees from top view), pronotal humerus forms a right angle; body concolorous brown (Veracruz, Mexico) . . . . . Pheidole xyston


 * Major: seen in dorsal-oblique view, humerus a smoothly rounded convexity; body color yellow, except for light brown posterior bands on the gastral tergites and a fuzzy-edged brown spot on the vertex (Choco, Colombia) . . . . . Pheidole lemnisca

12
return to couplet #10
 * Major: space between eye and antennal fossa lacks any rugulae or rugoreticulum, and is instead covered by longitudinal and circular carinulae . . . . . 13


 * Major: at least some of the space between the eye and antennal fossa occupied by rugoreticulum and/or rugulae . . . . . 14

13
return to couplet #12
 * Major: in side view, posterior rear half of head smooth and shiny; lateral margins of postpetiolar node seen from above acute-angular (Veracruz, Mexico) . . . . . Pheidole prolixa


 * Major: in side view, posterior rear half of head foveolate and opaque; lateral margins of postpetiolar node seen from above rounded (Costa Rica, Panama) . . . . . Pheidole ruida

14
return to couplet #12
 * Major: rugoreticulum confmed to the occiput and space between eye and antennal fossa . . . . . 15


 * Major: rugoreticulum extends continuously from occiput down the side of the head all or almost all the way to the eye . . . . . 16

15
return to couplet #14
 * Major: antennal scrobes present, although shallow; longitudinal carinulae on the antennallobes extend posteriorly all the way back to meet the rugoreticulum of the occiput (southern Brazil, Peru, Argentina) . . . . . Pheidole sospes


 * Major: antennallobes absent; longitudinal carinulae of frontal lobes confined to them, leaving almost all of the middle half of the dorsal surface of the head free of carinulae (Costa Rica) . . . . . Pheidole otisi

16
return to couplet #14
 * Major: antennal scrobes present; pronotal humeri with small patches of rugoreticulum (southeastern Brazil) . . . . . Pheidole termitobia


 * Major: antennal scrobes absent; pronotal humeri lacking rugoreticulum, being foveolate only . . . . . 17

17
return to couplet #16
 * Major: inner pair of hypos to mal teeth reduced to denticles, much smaller than outer pair. Minor: posterior dorsal half of head lacks carinulae; body blackish brown with metallescent blue reflections (Florida to Texas) . . . . . Pheidole metallescens


 * Major: inner pair of hypos to mal teeth strongly developed, as long as outer pair. Minor: longitudinal carinulae cover the posterior dorsal half of the head; head and mesosoma light reddish brown, and waist and gaster dark yellow, with no metallescent reflections anywhere (southeastern United States, Texas) . . . . . Pheidole dentigula

18
return to couplet #2
 * Major: in full-face view, rugoreticula near the lateral margins of the dorsal surface of the head extend continuously all the way from the occiput or close to it anteriorly to the level of the eyes . . . . . 19


 * Major: in full-face view rugoreticula at or near the occiput are limited to the occipital lobes, or to the nearby space just posterior to the antennal scrobes, or both, but do not also extend along the sides of the head anteriorly all the way to the level of the eyes . . . . . 23

19
return to couplet #18
 * Major: pronotal dorsum covered by transverse carinulae. Minor: posterior half of dorsal head surface and all of promesonotal dorsum covered by rugoreticulum (Costa Rica, southern Mexico) . . . . . Pheidole rectitrudis


 * Major: pronotal dorsum lacking carinulae. Minor: no rugoreticulum present on promesonotal dorsum . . . . . 20

20
return to couplet #19
 * Major: antennal scrobes present, and their surface conspicuously lacks carinulae or rugulae, causing it to contrast with the heavily rugoreticulate surface all around the scrobes (Para, Brazil) . . . . . Pheidole peltastes


 * Major: antennal scrobes absent; behind and mesad to the frontal lobes, where scrobes occur in many other species, the surface is covered by carinulae, rugulae, or rugoreticulum . . . . . 21

21
return to couplet #20
 * Major: in full-face view, central half of the posterior dorsum of the head all the way to the occiput free of carinulae or rugulae (Nicaragua) . . . . . Pheidole rectisentis


 * Major: in full-face view, central half of the posterior dorsum of the head covered by longitudinal carinulae or broken, irregular rugulae . . . . . 22

22
return to couplet #21
 * Major: carinulae originating on frontal lobes continue posteriorly all the way to the occipital border. Minor: body reddish yellow (Honduras, Belize) . . . . . Pheidole harrisonfordi


 * Major: carinulae originating on frontal lobes break up into irregular, fragmented rugulae before reaching the occipital border, and in full-face view leave a thin strip of the occiput anterior to the border smooth (montane Ecuador) . . . . . Pheidole camilla

23
return to couplet #18
 * Major: in full-face view, the frontal lobes, most of the space between the eyes and antennal fossae, as well as the occipital lobes, rugoreticulate, but most of the large space between the level of the eyes and the level of the occipital lobes is devoid of rugoreticulum, rugulae, or carinulae (montane Veracruz, Mexico) (placed in the fallax group; also keyed out here to ensure identification) . . . . . Pheidole roushae


 * Major: in full-face view, the longitudinal carinulae extend posteriorly either to the occipital border or to the rugoreticulum just anterior to the border . . . . . 24

24
return to couplet #23
 * Major: in full-face view, most or all of the longitudinal carinulae or rugulae originating on the frontal lobes continue unbroken all the way to the occipital border or just anterior to it


 * Major: in full-face view, the longitudinal carinulae or rugulae originating on the frontal lobes are interrupted by rugoreticulum before they reach the occipital border . . . . . 28

25
return to couplet #24
 * Major: rugoreticulum extends from the point reached by the tips of the antennal scapes all the way to the outer margins of the occipital lobes; pronotal dorsum covered by transverse carinulae. Minor: anterior half of pronotal dorsum rugoreticulate (Brazil and Misiones, Argentina) (consider also bucolica, placed in provisional synonymy under rudigenis, but a possible distinct species; see rudigenis Diagnosis) . . . . . Pheidole rudigenis


 * Major: rugoreticulum limited to a patch just posterior to the point reached by the tip of the antennal scapes, and does not reach the outer margins of the occipital lobes. Minor: pronotal dorsum lacks rugoreticulum . . . . . 26

26
return to couplet #25
 * Major: shallow antennal scrobes present, the surface of their posterior half foveolate but free of carinulae, rugulae, or rugoreticulum; body medium brown. Major and minor: pronotum completely foveolate and opaque (Colombia) . . . . . Pheidole tayrona


 * Major: antennal scrobe absent and space laterad to posterior part of the frontal lobes filled in with longitudinal carinulae; body yellow or reddish brown. Major and minor: pronotum foveolate or smooth and shiny . . . . . 27

27
return to couplet #26
 * Major: rugoreticulum present between eye and antennal fossa; body concolorous yellow. Major and minor: pronotum entirely foveolate and opaque (reticulate-headed form of the species, which also varies through intermediates to a form lacking rugoreticulum on the head; see also couplet 131) (widespread and abundant through the American tropics and, possibly as an adventive, also occurs in Florida; often carried accidentally by commerce) . . . . . Pheidole flavens (in part - also )


 * Major: rugoreticulum not present between eye and antennal fossa; body reddish brown, with head anterior to the eyes medium yellow, and tibiae and tarsi contrasting pale yellow (southern Mexico) . . . . . Pheidole albipes

28
return to couplet #24
 * Major: longitudinal carinulae arising from the space between the eye and frontal lobe do not extend posteriorly beyond the level of the eye; head elongate (Head Length more than 1.2 X Head Width). Minor: dorsa of head and pronotum foveolate and opaque (Costa Rica) . . . . . Pheidole longinoi


 * Major: at least some of the longitudinal carinulae arising between the eye and frontal lobe extend posteriorly all the way to the rugoreticulum located on or near the occiput; head not elongate (Head Length less than 1.1 X Head Width). Minor: dorsa of head and pronotum foveolate and opaque or smooth and shiny . . . . . 29

29
return to couplet #28
 * Major: in full-face view, rugoreticulum covers all of the occiput except the center, but extends anteriorly only to within 2 X length of eye of the posterior margin of the antennal scrobes; humeral corners not rugoreticulate. Minor: dorsa of head and pronotum foveolate and opaque (Amazonian Peru) . . . . . Pheidole ademonia


 * Major: in full-face view, rugoreticulum approaches occiput only to within an eye length, leaving the remaining strip in front of the occipital border smooth and shiny; humeral corner rugoreticulate. Minor: dorsa of head and pronotum smooth and shiny (montane Dominica, West Indies) . . . . . Pheidole perkinsi

30
return to couplet #1
 * Major: in full-face view, head rectangular and very elongate (Head Length 1.6 X longer than Head Width); dorsal head surface often lacking carinulae or rugulae of any kind (Costa Rica to Colombia) . . . . . Pheidole christopherseni


 * Major: in full-face view, head variable in shape among species (Head Length never as much as 1.SX longer than Head Width); carinulae always present and usually abundant, at least in concentric circles around the antennal fossae . . . . . 31

31
return to couplet #30
 * Major: rugoreticulum present somewhere on dorsal head surface, even if only as patches between the eyes and antennal fossae or as cross-hatching on the frontal lobes . . . . . 32


 * Major: rugoreticulum completely absent from the dorsal surface of the head . . . . . 66

32
return to couplet #31
 * Major: in full-face view, entire posterior half of the dorsal surface of the head is covered by longitudinal carinulae or rugulae, or carinulae plus patches of rugoreticulum, with the possible exception of the occiput and surface of the antennal scrobes . . . . . 33


 * Major: large portions of the posterior half of the dorsum of the head, such as most of the sides of the head, not just the occiput and antennal scrobes, are free of carinulae, rugulae, and rugoreticulum . . . . . 49

33
return to couplet #32
 * Major: in full-face view, carinulae or rugulae on the dorsal head surface extend posteriorly all the way to the occipital border . . . . . 34


 * Major: in full-face view, carinulae or rugulae on the dorsal head surface do not extend all the way to the occipital border; all or at least part of the occipital lobes lack them . . . . . 39

34
return to couplet #33
 * Major: prominent humeral “sharkfin” horns present on pronotum, projecting beyond the lateral margins of the rest of the pronotum even when viewed from directly above, their apices forming acute angles (Amazonian Peru) . . . . . Pheidole gilva


 * Major: humeral horns absent; humeral margins form evenly rounded convexities with no prominent protrusions . . . . . 35

35
return to couplet #34
 * Major: anterior third of pronotum lacking carinulae and rugoreticulum . . . . . 36


 * Major: anterior third of pronotum covered by transverse carinulae and patches of rugoreticulum . . . . . 37

36
return to couplet #35
 * Major: head broader than long; in full-face view, it expands posteriorly to reach maximum width at the occiput; conspicuously bicolored, with mesosoma, waist, and part of head brown, and rest of body yellow; pronotal spine thick and as long as the basal face of the propodeum anterior to it (Dominican Republic) . . . . . Pheidole harlequina


 * Major: head square-shaped and exactly as broad as long; body and head concolorous yellow; propodeal spine medium-wide and only one-third as long as the basal face of the propodeum (Guatemala) (see also subreticulata) . . . . . Pheidole breviscapa (= Pheidole perpusilla)

37
return to couplet #35
 * Major: antennal scrobes absent; body reddish brown (Argentina) . . . . . Pheidole heterothrix


 * Major: antennal scrobes present; body yellow or brown . . . . . 38

38
return to couplet #37
 * Major: rugoreticulum on dorsal head surface limited to the space between the eye and the antennal fossa (southern Mexico, Costa Rica) (also, check mittermeieri) . . . . . Pheidole glomericeps


 * Major: rugoreticulum on dorsal head surface limited to small space immediately behind the antennal scrobe (Colombia) . . . . . Pheidole charazana

39
return to couplet #33
 * Major and minor: in side view, profile of occiput bears several clavate hairs, the pilosity of the promesonotal dorsum consists almost entirely of several pairs of clavate hairs, and several more clavate hairs occur on the dorsa of the petiolar and postpetiolar nodes (Texas) . . . . . Pheidole constipata


 * Major and minor: pilosity of occiput, promesonotum, and waist consists of abundant, non-clavate hairs . . . . . 40

40
return to couplet #39
 * Major: seen from above and obliquely, pronotal humerus angulate or subangulate . . . . . 41


 * Major: seen from above and obliquely, pronotal humerus smoothly rounded . . . . . 43

41
return to couplet #40
 * Major: humeral angle, viewed from above and obliquely, is acute; in side view, frontal lobe extends forward as a prominent, right-angular flange (Costa Rica to Brazil, Peru, and Ecuador) (placed in the tristis group; also keyed out here to ensure identification) . . . . . Pheidole cramptoni


 * Major: humeral angle obtuse; frontal lobe in side view rounded and not protuberant . . . . . 42

42
return to couplet #41
 * Major: antennal scrobes present; promesonotal dorsum and anterior half of first gastral tergite foveolate and opaque (Tamaulipas, Mexico) . . . . . Pheidole rectiluma


 * Major: antennal scrobes absent; promesonotal dorsum and all of first gastral tergite smooth and shiny (Costa Rica to Amazonian Peru) . . . . . Pheidole tennantae (in part - also )

43
return to couplet #40
 * Major: rugoreticulum begins at eye level and extends posteriorly to about halfway between the level of the posterior margin of the eye and the level of the occiput, and it also extends to the space ventral to ("behind") the eye (Colombia) . . . . . Pheidole quadriceps


 * Major: rugoreticulum limited to the space between the eye and antennal fossa . . . . . 44

44
return to couplet #43
 * Major: anterior half of pronotal dorsum covered with transverse carinulae . . . . . 45


 * Major: pronotal dorsum entirely free of carinulae . . . . . 46

45
return to couplet #44
 * Major: seen from above, postpetiolar node oval in outline, and sides of the node mostly smooth and shiny. Minor: longitudinal carinulae present behind (ventral to) the eye and those immediately mesad to the eye extend past the posterior margin of the eye by an eye's length; a small amount of reticulum present between eye and antennal fossa (West Indies, introduced into U. S. Gulf States) . . . . . Pheidole moerens


 * Major: seen from above, postpetiolar node trapezoidal in shape, widest near anterior border, and its sides foveolate and opaque. Minor: no carinulae present ventral to eye, and those immediately mesad to the eye do not extend an eye's length past the posterior margin of the eye; no reticulum present on head (Argentina) . . . . . Pheidole bruchella

46
return to couplet #44
 * Major: in side view, a separate mesonotal convexity well developed; seen from above, lateral margins of postpetiolar node angulate (Amazonian Peru) . . . . . Pheidole sabella


 * Major: in side view, mesonotal convexity not separately developed, the promesonotal profile forming a single smooth curve; from above, lateral margins of postpetiolar node rounded . . . . . 47

47
return to couplet #46
 * Major: lower half of mesopleuron foveolate, opaque, and with longitudinal rugulae; occiput bears scattered conspicuous foveae; head bicolored, dark yellow anterior to the eyes and brown behind (Venezuela) . . . . . Pheidole pariana


 * Major: lower half of mesopleuron smooth and shiny; occiput lacking foveae; head concolorous yellow or brown . . . . . 48

48
return to couplet #47
 * Major: many hairs along dorsal profiles of promesonotum and first gastral tergite 2 X eye length; in side view, space between metanotal groove and propodeal spiracle longitudinally rugulate (Amazonian Peru and Ecuador) . . . . . Pheidole caracalla


 * Major: hairs along dorsal profiles of promesonotum and first gastral tergite at most about 1 X eye length; in side view, rugulae do not cover the space between the metanotal groove and propodeal spiracle (St. Vincent and Puerto Rico) . . . . . Pheidole orbica

49
return to couplet #32
 * Major and minor: pronotal dorsum completely covered by coarse rugoreticulum (Costa Rica) . . . . . Pheidole carinata


 * Major and minor: pronotal dorsum lacking rugoreticulum . . . . . 50

50
return to couplet #49
 * Major: pronotal dorsum completely covered by transverse carinulae (Costa Rica) . . . . . Pheidole brachyops


 * Major: pronotal dorsum free of carinulae, or, at most, a few carinulae occur on the anteriormost strip, or humeri, or both . . . . . 51

51
return to couplet #50
 * Major: rugoreticulum occurs as a band across the dorsum of the head from eye to eye and across the frontal lobes without a break; in side view, posteriormost carinulae departing from anterior margin of the eye travel obliquely downward toward the lower ventral corner of the head (Argentina) . . . . . Pheidole carapunco


 * Major: rugoreticulum interrupted in the center of the dorsum of the head by the longitudinal carinulae of the frontal lobes; in side view, carinulae departing from anterior margin of the eye travel straight forward to the anterior clypeal border or even slightly upward toward the dorsal surface of the head . . . . . 52

52
return to couplet #51
 * Major: in side view, rugoreticulum completely surrounds the eye and continues ventrally across the gena to the lower margin of the head (Campeche, Mexico) . . . . . Pheidole dumicola


 * Major: in side view, rugoreticulum does not extend all the way around the eye or onto the gena . . . . . 53

53
return to couplet #52
 * Major: seen from above, margins of postpetiolar node form spines or at least acute angles . . . . . 54


 * Major: seen from above, the postpetiolar node forms an oval or trapezoid, its margins either round or obtuse-angular . . . . . 60

54
return to couplet #53
 * Major: seen from above, margins of postpetiolar node taper into spines, and the humeri form acute angles that project slightly beyond the margins of the rest of the pronotum beneath them (Arizona) . . . . . Pheidole furtiva


 * Major: seen from above, margins of postpetiolar node are acute-angular but not tapered into spines; humeri do not extend as acute angles beyond margins of rest of pronotum . . . . . 55

55
return to couplet #54
 * Major: hypostomum bearing 3 teeth; first gastral tergite partly shagreened and opaque . . . . . 56


 * Major: hypostomum bearing 4-5 teeth; first gastral tergite completely smooth and shiny . . . . . 57

56
return to couplet #55
 * Major: in side view, posterior half of ventral surface of head foveolate and opaque. Minor: in side view, propodeal spine more than half as long as the basal propodeal face anterior to it (Oaxaca, Mexico) . . . . . Pheidole oaxacana


 * Major: in side view, posterior half of ventral surface of head smooth and shiny. Minor: in side view, propodeal spine only one-third as long as the basal propodeal face anterior to it (Veracruz, Mexico) . . . . . Pheidole scabriventris

57
return to couplet #55
 * Major: shallow antennal scrobes present (Arizona) . . . . . Pheidole juniperae


 * Major: shallow antennal scrobes absent . . . . . 58

58
return to couplet #57
 * Major: posterior half of dorsal surface of head covered by widely spaced, conspicuous, coarse, and piligerous punctures (Mexico City) . . . . . Pheidole tragica


 * Major: posterior half of dorsal surface of head lacks conspicuous piligerous punctures . . . . . 59

59
return to couplet #58
 * Major: dorsal surface of head bicolored, with occiput and anterior strip of head surface yellow and middle section light brown. Minor: occiput foveolate and opaque to feebly shiny; carinulae immediately mesad to eye extend posteriorly past eye halfway to occipital border (southeastern Mexico) . . . . . Pheidole chalca


 * Major: dorsal surface of head concolorous reddish yellow. Minor: occiput smooth and shiny; carinulae mesad to eye do not extend posteriorly past the eye (Oaxaca, Mexico) . . . . . Pheidole mixteca

60
return to couplet #53
 * Major: concolorous yellow, except for a unique “mask” of light brown that extends across all the head exclusive of the occipital lobes and the genae anterior to the eyes. Minor: nuchal collar present (Costa Rica) . . . . . Pheidole nasutoides


 * Major: species variously yellow to brown; head concolorous or, if bicolored, the contrasting zones are in different shades of brown. Minor: nuchal collar present or absent . . . . . 61

61
return to couplet #60
 * Major: seen from the side, what appears to be the profile of the metanotal dorsum is a distinct convexity, which separates the mesonotal convexity from the low rise of the propodeal basal face. Minor: nuchal collar present (Santa Catarina, Brazil) . . . . . Pheidole flavida


 * Major: seen from the side, profile of meta notal dorsum is a narrow concave groove, as typical for the genus, with no convexity. Minor: nuchal collar absent . . . . . 62