Key to Pheidole diligens group

This worker key is based on:

This large and diverse assemblage, almost exclusively Neotropical in distribution (I have recently seen one still undescribed species from the Patagonia Mountains of southern Arizona), comprises species of medium size, approximately heart-shaped heads, prominent mesonotal convexities, and restricted, mostly nonreticulate sculpturing. The diligens group is contiguous and even overlapping with the fallax group in the variation of these traits taken singly, but in the great majority of cases nest series can be placed in one or the other of the two groups by glancing at the full suite of characters. On the other hand, whether the group is monophyletic or a cluster of convergent subgroups remains to be determined. (One species, Pheidole riveti'' of Ecuador, cannot be keyed precisely here because the antennae of the lectotype are missing; check this species directly at decision points as noted in the key.)

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 * Pheidole
 * "New World Pheidole" Wilson 2003

1

 * Propodeal spine greatly broadened and shortened or lacking altogether in the major and usually in the minor also; rather, the basal and descending faces of the propodeum viewed from the side come together to form a low, obtuse, or right angle . . . . . 2


 * Propodeal spine present in major and minor, at least in the form of a denticle or small, raised acute angle . . . . . 10

2
return to couplet #1
 * Major: antennal scape reaches or slightly exceeds the occipital corner . . . . . 3


 * Major: antennal scape fails to reach the occipital corner by at least twice its own maximum width (also, check riveti) . . . . . 4

3
return to couplet #2
 * Major: scape slightly exceeds occipital corner; occipital corner in full-face view subangular, not forming arc of circle (Amazonian Brazil, Paraguay) . . . . . Pheidole chrysops


 * Major: scape falls slightly short of occipital corner; occipital corner smoothly rounded to form the arc of a circle (Bolivia) . . . . . Pheidole vafella

4
return to couplet #2
 * Major: most of dorsal surface of head capsule covered by longitudinal carinulae . . . . . 5


 * Major: carinulae of head capsule almost entirely limited to small area near the eyes . . . . . 6

5
return to couplet #4
 * Mesosoma of major and minor largely covered by transverse carinulae (Colombia) (also, check riveti) . . . . . Pheidole laelaps


 * Mesosoma of major and minor lacking transverse carinulae (Amazonian Peru) . . . . . Pheidole demeter

6
return to couplet #4
 * Pronotum and posterior dorsal half of head of minor partly covered by transverse carinulae (Costa Rica to Colombia) . . . . . 7


 * Pronotum and posterior dorsal half of head of minor lacking carinulae, and instead is entirely smooth and shiny . . . . . 8

7
return to couplet #6
 * Major: carinulae originating at inner side of eye travel transversely to the top of the antennal fossa. Minor: head possesses nuchal collar (Colombia) . . . . . Pheidole seligmanni


 * Major: carinulae originating at inner side of eye travel anteriorly to the anterior margin of the head capsule. Minor: head lacks nuchal collar (Costa Rica to Colombia) . . . . . Pheidole alfaroi (in part - also )

8
return to couplet #6
 * Major: head elongate (Head Length 1.2X Head Width). Minor: in side view, basal face of propodeum joins descending face in a smooth curve (Brazilian Amazon) . . . . . Pheidole strigosa


 * Major: head not elongate (Head Length less than 1.1 X Head Width). Minor: juncture of basal and descending propodeal faces in side view bearing short spine or at least angulate (Costa Rica) . . . . . 9

9
return to couplet #8
 * Major: scape broadened near the base, its width there equal to or greater than the maximum width of the transects along its distal half. Minor: dorsal surface of propodeurn lacks transverse carinulae . . . . . Pheidole laticornis


 * Major: scape much narrower near its base than in transects along its distal half. Minor: dorsal surface of propodeurn covered by transverse carinulae . . . . . Pheidole diana

10
return to couplet #1
 * Major: scape reaches within half of its own maximum width of the occipital corner, or exceeds it . . . . . 11


 * Major: scape fails to reach occipital corner by at least half its own maximum width . . . . . 30

11
return to couplet #10
 * Major: carinulae and other sculpturing immediately laterad to the frontal lobes (i .e., for a distance laterad equal to the Eye Length) either not extending beyond the level of posterior margin of the eye or, if they do, extending at most for a distance less than half the length of the eye; surface of head immediately laterad to the eye and posterior to it smooth and shiny . . . . . 12


 * Major: carinulae and other sculpturing immediately laterad to the frontal lobes extending posteriorly past the posterior eye margin for a distance greater than the Eye Length; surface of head immediately laterad to the eye and posterior to it often sculptured . . . . . 26

12
return to couplet #11
 * Major: profile of mesosoma completely bare of pilosity or at most with several standing hairs . . . . . 13


 * Major: profile of mesosoma with abundant standing hairs . . . . . 15

13
return to couplet #12
 * Major and minor: mesopleuron foveolate only, lacking carinulae and rugulae; scape exceeding margin of occipital corner by its length or slightly more; yellow (Brazilian Amazon) . . . . . Pheidole lemur


 * Major and minor: mesopleuron with weak but distinct longitudinal carinulae or rugulae; scapes of major just reaching margin of occipital corner; dark brown (Central America) . . . . . 14

14
return to couplet #13
 * Major: space between eye and antennal insertion partly rugoreticulate; propodeal spine straight and tapered to a point (Honduras) . . . . . Pheidole anima


 * Major: space between eye and antennal insertion entirely carinulate, with no rugoreticulurn; propodeal spine relatively thick and blunt-tipped (Guatemala) . . . . . Pheidole tschinkeli

15
return to couplet #12
 * Major: scape exceeds the occipital corner by at least 2X its own maximum width . . . . . 16


 * Major: scape just reaches the occipital corner, or extends beyond by no more than its own maximum width . . . . . 19

16
return to couplet #15
 * Major and minor: in side view, propodeal spine at least half as long as the basal face anterior to it . . . . . 17


 * Major and minor: in side view, propodeal spine less than one-fourth as long as the basal face anterior to it . . . . . 18

17
return to couplet #16
 * Major: eye very large, its maximum length greater than the distance from its anterior border to the genal border; frontal lobes longitudinally carinulate (Amazonian Peru) . . . . . Pheidole scimitara


 * Major: maximum eye length much less than the distance from the anterior border of the eye to the genal border; frontal lobes smooth and shiny (Costa Rica) . . . . . Pheidole tanyscapa

18
return to couplet #16
 * Major: occiput bearing a tuft of standing hairs conspicuously denser than the hairs on the main dorsal surface of the head; within the occipital tuft on the surface is a “crown” of scattered but conspicuous foveae; major reddish brown, minor brownish yellow (widespread circum-Caribbean, possibly tramp species) . . . . . Pheidole cocciphaga


 * Major: occiput lacking a special tuft of hairs or foveae on occiput; major reddish yellow, minor yellowish brown (Venezuela, Amazonian Brazil) . . . . . Pheidole longiscapa

19
return to couplet #15
 * Major and minor: in side view, propodeal spine as long as the basal face of the propodeum anterior to it (Costa Rica) . . . . . Pheidole sicaria


 * Major and minor: in side view, propodeal spine less than one-fourth the length of the basal face anterior to it . . . . . 20

20
return to couplet #19
 * Major: all of mesothorax and petiole smooth and shiny except for small patches of weak foveolae and rugulae on the lower part of episternum and center of side of propodeum (Colombia) . . . . . Pheidole tenuis


 * Major: almost all of mesothorax and petiole foveolate and opaque . . . . . 21

21
return to couplet #20
 * Major: several parallel carinulae run from each frontal lobe back over the head capsule to at least halfway between the level of the posterior border of the eye and the occipital border. . . . . . 22


 * Major: carinulae from each frontal lobe reach at most a quarter of the distance from the level of the posterior border of the eye to the occipital border . . . . . 23

22
return to couplet #21
 * Major and minor: parallel transverse carinulae prominent on anterior fourth of pronotum and also present on dorsal surface of propodeum of major; all of the side of major mesothorax (mesopleuron) foveolate and opaque (Panama to Bolivia) . . . . . Pheidole veletis


 * Major and minor: several broken transverse carinulae present on extreme anterior strip of pronotum, and absent elsewhere on mesosomal dorsum of major and minor; lower half of major mesopleuron smooth and shiny (Sao Paulo, Brazil) . . . . . Pheidole perryorum

23
return to couplet #21
 * Small (Head Width of major 0.8 mm) brown species. Minor: eye large and placed forward, its length as great as the distance from eye to anterior genal border (Amazonian Peru) . . . . . Pheidole machetula


 * Larger (Head Width of major 0.9-1.0 mm), brown or yellow species. Minor: Eye Length much less than the distance of anterior border of eye to the anterior genal border . . . . . 24

24
return to couplet #23
 * Major: in full-face view, no hairs project beyond the margin of head posterior to level of eyes; a small amount of rugoreticulum present, in addition to carinulae, between frontal lobe and eye (Santa Catarina, Brazil) . . . . . Pheidole laevifrons


 * Major: in full-face view, dense hairs projecting beyond margin of head posterior to level of eyes; no rugoreticulum, only carinulae, present between frontal lobe and eye . . . . . 25

25
return to couplet #24
 * Major: scape exceeds occipital corner by its own maximum width; eye small, its length only 0.14 mm; yellow (Ceara, Brazil) . . . . . Pheidole rochai


 * Major: scape just reaches occipital corner; eye length 0020 mm; reddish brown (Santa Catarina, Brazil) (also, check chrysops) . . . . . Pheidole blumenauensis

26
return to couplet #11
 * Major and minor: dorsal surfaces of promesonotum and propodeum covered by parallel transverse carinulae (Venezuelan tepui) . . . . . Pheidole tepuicola


 * Major and minor: dorsal surface of promesonotum and propodeum lack carinulae . . . . . 27

27
return to couplet #26
 * Major: head sparsely pilose; when head is viewed full face, at most several hairs project beyond the occipital border . . . . . 28


 * Major: head densely pilose; when head is viewed in full face, at least 10 and usually many more hairs project beyond the occipital border

28
return to couplet #27 developed, in profile half as long as the propodeal basal face anterior to it (Costa Rica). . . . . Pheidole pubiventris
 * Major: extensive area between eye and antennal insertion rugoreticulate; anterior fourth of first gastral tergite shagreened and opaque. Minor: propodeal spine well

rugoreticulum; all of first gastral tergite smooth and shiny. Minor: propodeal spine reduced to a tiny denticle (Coahuila, Mexico). . . . . Pheidole ariel
 * Major: area between eye and antennal insertion entirely cannulate, lacking

29
return to couplet #27
 * Major: in full-face view, parallel transverse and curving carinulae run from the posterior ends of frontal carinae to the eye; mesonotal convexity in side view evenly rounded. Minor: light brown with violaceous reflections (Costa Rica) . . . . . Pheidole violacea


 * Major: in full-face view, carinulae originating from near posterior ends of frontal carinae run obliquely to a level well above the eye; mesonotal convexity in side view forming a blunt-tipped right angle. Minor: dark yellow, lacking violaceous reflections (Meta, Colombia) . . . . . Pheidole spilota

30
return to couplet #10
 * Major: sculpturing between eye and antennal fossa at least in part rugoreticulate, i.e., consisting in part of at least several cross-carinulae that connect adjacent longitudinal carinulae . . . . . 31


 * Major: no rugoreticulum between eye and antennal fossa, only concentric and longitudinal carinulae or unconnected rugulae . . . . . 56

31
return to couplet #30
 * Major: a large part of the dorsal surface of the head posterior to the level of the eyes weakly rugoreticulate as well as foveolate, and opaque (Costa Rica) . . . . . Pheidole texticeps


 * Major: no part of the dorsal surface of the head posterior to the level of the eyes bears a rugoreticulum . . . . . 32

32
return to couplet #31
 * Major: pilosity very sparse; no hairs project anywhere beyond margin of head viewed in full face, except those projecting beyond anterior margin of clypeus . . . . . 33


 * Major: pilosity moderately to very abundant; at least 5 or 6 hairs, usually many more, project beyond margin of head seen in full face, in addition to those at the anterior clypeal border . . . . . 47

33
return to couplet #32
 * Major: entire rear half of dorsal surface of head foveolate and opaque . . . . . 34


 * Major: rear half of dorsal surface of the head smooth and shiny, or at least the occiput and/or a broad central swath of the vertex smooth and shiny . . . . . 39

34
return to couplet #33
 * Major: in side view, rear third of petiole bears a low node and is bent downward at a nearly right angle to the anterior peduncle (Mato Grosso, Brazil) . . . . . Pheidole cyrtostela


 * Major: in side view entire petiole straight and surmounted posteriorly by a high, well-developed node . . . . . 35

35
return to couplet #34
 * Major: seen in side view, dorsal surface of first gastral tergite covered by dense felt of very short erect and suberect pubescence of even height, with a sparse scattering of much longer hairs; a pair of clavate hairs present on anterior dorsum of pronotum (Colombia) . . . . . Pheidole brandaoi


 * Major: specialized pilosity described above not present . . . . . 36

39
return to couplet #33
 * Major: pronotal dorsum smooth and shiny . . . . .40


 * Major: pronotal dorsum foveolate and opaque . . . . . 44

40
return to couplet #39
 * Major and minor: large (Head Width of major 1.6 mm) with long spines that equal in length the basal face of the propodeum anterior to it, viewed from the side; color very dark, from deep brown to black (Brazilian Amazon) . . . . . Pheidole lancifera


 * Major and minor: smaller (Head Width of major 0.9-1.3 mm) with spines that are at most only slightly longer than half the length of the propodeal basal face anterior to it, in side view; color of species variously yellow to blackish brown . . . . . 41

41
return to couplet #40
 * Major: a strip from eye to occiput foveolate and opaque; body dark brown, gaster black. Minor: occiput broad, lacking nuchal collar (Mexico, Costa Rica) . . . . . Pheidole piceonigra


 * Major: region between eye and occiput smooth and shiny; according to species, most of body yellow to reddish brown. Minor: according to species, body with or without nuchal collar . . . . . 42

42
return to couplet #41
 * Major: in full-face view, tip of scape reaches lateral margin of head much less than halfway from eye to occipital corner; humerus, in dorsal-oblique view (mesosoma rotated around long axis 45 degrees from top view), subangulate; head tricolored, with clypeus yellow, space between clypeus and level of eye light brown, and rest of head dark reddish brown (Amazonian Peru) . . . . . Pheidole davidsonae


 * Major: in full-face view, tip of scape reaches lateral edge of head well above midpoint between eye and occipital corner; humerus, in dorsal-oblique view smoothly rounded; head concolorous yellow or brown . . . . . 43

43
return to couplet #42
 * Major: scape approaches occipital corner to a distance of less than its own maximum width; in side view, propodeal spine longer than half the length of the basal face of the propodeum anterior to it; body yellowish to medium reddish brown. Minor: occiput broad, lacking nuchal collar (Costa Rica, Panama) . . . . . Pheidole perdiligens


 * Major: scape approaches occipital corner to a distance about equal to twice its own maximum width; in side view, propodeal spine less than half as long as the basal face of the propodeum anterior to it; body dark brown. Minor: occiput narrow, with nuchal collar (Peruvian and Ecuadoran Amazon) . . . . . Pheidole gagates

44
return to couplet #39
 * Major: all of dorsal surface of head capsule except occiput foveolate and opaque; all of frontal lobes and region between them posterior to the frontal triangle covered by parallel longitudinal carinulae (Argentina) . . . . . Pheidole nubila


 * Major: at most only the anterior half of the dorsal head surface foveolate and opaque, the remainder smooth and shiny; a wide central space between frontal-lobe carinulae is smooth and shiny . . . . . 45

45
return to couplet #44
 * Major: propodeal spine thin, needle-like, one-third as long as the dorsal face of the propodeum anterior to it. Minor: head narrowed posteriorly, with thin nuchal collar (Santa Cruz, Bolivia) . . . . . Pheidole zelata


 * Major: propodeal spine thick, in side view, roughly equilateral-triangular in shape, only one-fourth as long as the dorsal face of the propodeum anterior to it. Minor: occiput broad, its border shallowly concave, lacking nuchal collar . . . . . 46

46
return to couplet #45
 * Major: promesonotal profile, in dorsal-oblique view (mesosoma rotated around long axis 45 degrees from top view), contains 3 prominent convexities, 2 pronotal and one mesonotal. Minor: frontal lobes lack carinulae. Major and minor: yellow (Argentina, Bolivia, Brazil) . . . . . Pheidole triconstricta


 * Major: promesonotal profile, in dorsal-oblique view, contains only 2 prominent convexities, the pronotal and mesonotal respectively. Minor: frontal lobes possess longitudinal carinulae along outer edges. Major: light brown, anterior quarter of head capsule reddish yellow. Minor: medium brown (Minas Gerais, Brazil) . . . . . Pheidole geraesensis

47
return to couplet #32
 * Major: pronotal dorsum foveolate and opaque . . . . . 48


 * Major: pronotal dorsum smooth and shiny . . . . . 49

48
return to couplet #47
 * Major: scape falls short of occipital corner by only 1 X its own maximum width; longest hairs on dorsa of pronotum and gaster 2X length of eye. Minor: occiput narrowed behind, with thin nuchal collar (Costa Rica) . . . . . Pheidole hoelldobleri


 * Major: scape falls short of occipital corner by 2X its own maximum width; longest hairs on dorsa of pronotum and gaster only about as long as length of eye. Minor: occiput broad behind, and lacks nuchal collar (southern and central Brazil) . . . . . Pheidole rufipilis

49
return to couplet #47
 * Major and minor: in side view, many hairs on the dorsa of head and gaster are 2X (and some 3X) length of eye (Brazilian and Amazonian Peru) . . . . . Pheidole longiseta


 * Major and minor: in side view, at most only several hairs as long as 2X the length of the eye, the great majority much shorter . . . . . 50

50
return to couplet #49
 * Major: longitudinal carinulae immediately mesad to eyes extending one-fourth or more the distance to the occipital border . . . . . 51


 * Major: longitudinal carinulae immediately mesad to eyes not reaching beyond the posterior border of the eyes . . . . . 52

51
return to couplet #50 occipital border; sides of mesonotal convexity and propodeum just above and in front of the spiracle carinulate (Argentina, southern Brazil). . . . . Pheidole laevinota
 * Major: longitudinal carinulae immediately mesad to eyes reaching halfway to


 * Major: longitudinal carinulae immediately mesad to eyes reaching only one-fourth distance to occipital border; sides of mesonotal convexity and area above and front of propodeal spiracles lacking carinulae (Argentina) (placed in the fallax group; also keyed out here to ensure identification) . . . . . Pheidole pampana

52
return to couplet #50
 * Major: in side view, dense layers of hairs project beyond both the dorsum and venter of the first gastral tergite, and in full-face view a similar dense fringe of hairs project from around the entire margin of the head (Argentina) (placed in the fallax group; also keyed out here to ensure identification) . . . . . Pheidole dione


 * Major: in side view, hairs are sparse along the profiles of the above segments, usually fewer than 10 on each tergite . . . . . 53

53
return to couplet #52
 * Major: anterior fourth of first gastral tergite shagreened and opaque; in side view, propodeal spine more than half as long as the length of the basal face of the propodeum anterior to it. Minor: in full-face view, rear half of head strongly narrowed, with a conspicuous nuchal collar (Suriname, Amazonian Brazil) . . . . . Pheidole coffeicola


 * Major: anterior fourth of first gastral tergite smooth and shiny; in side view, propodeal spine no more than one-third as long as the length of the basal face anterior to it. Minor: in full -face view, rear half of head only slightly or moderately narrowed, with at most a very thin, inconspicuous collar . . . . . 54

54
return to couplet #53
 * Major: in side view, mesonotal convexity low, its length across the base 2X its height; propodeal spine short and blunt, approximately the shape of an equilateral triangle. Major and minor: clear dark yellow (southeastern Brazil) . . . . . Pheidole peregrina


 * Major: in side view, mesonotal convexity very prominent, approaching equilateral triangle in outline; propodeal spine longer and sharp, forming an acute triangle. Major and minor: yellowish brown to medium brown . . . . . 55

55
return to couplet #54
 * Major: lower half of mesopleuron foveolate and opaque; anterior half of pronotal dorsum with several short transverse rugulae; yellowish brown, gaster a shade darker than rest of body. Minor: head narrowed somewhat posteriorly, with an inconspicuous nuchal collar (Colombia, Bolivia) . . . . . Pheidole seeldrayersi


 * Major: lower half of mesopleuron smooth and shiny; pronotal dorsum lacking carinulae; reddish brown. Minor: head not tapered posteriorly and lacking a nuchal collar (Argentina and southern Brazil) (placed in the fallax group; also keyed out here to ensure identification; see also the closely similar eidmanni in the fallax group) . . . . . Pheidole nitidula

56
return to couplet #30
 * Major: in side view, rear third of petiole bearing a low node and bent downward at nearly a right angle to the anterior peduncle (Amazonian Brazil) . . . . . Pheidole camptostela


 * Major: in side view entire petiole straight and surmounted by a high, well-developed node . . . . . 57