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This is a key to the Pheidole species known from the Barva Transect. The Barva transect extends from La Selva Biological Station, at 50m elevation in the Atlantic lowlands, to the highest surveyed station near the peak of Volcan Barva, at about 2300m. This region is receiving extensive survey work as a part of Project ALAS and Conservation International's TEAM project.
This key is being posted in an incomplete and provisional state. It has known problems, few figures, and some terrible couplets. The missing figures will appear in your browser as little question marks because the instructions are present in the html document, awaiting the posting of figures. But this is better than nothing, and is needed for specimen sorting activities associated with the above projects.
10b. First gastral tergite completely smooth and shining: 110
20a Promesonotal suture distinctly impressed: 30
20b. Promesonotal suture weakly impressed or absent: 60
30a Head with nuchal collar: 40
30b. Head lacking nuchal collar: 50
40a Color yellow to brown; propodeal spines very long: Pheidole fiorii
40b. Color brown; propodeal spines relatively shorter: Pheidole hoelldobleri
50a Pilosity bristly, with erect setae short, stiff, dark brown, some of them flattened and expanded at the tip: Pheidole spathipilosa
50b. Pilosity thin and flexuous: Pheidole biconstricta
60a WL greater than 1mm; propodeal spines long: 70
60b. WL less than 1mm; propodeal spines medium length to short: 80
70a Propodeal spines very long; face smooth with silky luster; head with nuchal collar: Pheidole rogeri
70b. Propodeal spines not as long; face punctatorugose, without silky luster; head without nuchal collar: Pheidole cephalica
80a Side of pronotum smooth and shining (scapes foveolate; clypeus longitudinally rugose; frontal carinae elevated, flange-like anteriorly; face and most of mesosoma uniformly foveolate, overlain with a silky luster and violaceous reflections; first gastral tergum largely smooth and shining, but also with silky luster and violaceous reflections, and anterior fourth with feeble clathrate sculpture; soldier with strongly phragmotic head): Pheidole colobopsis
80b. Side of pronotum uniformly foveolate: 90
90a Color yellow; head rounded behind, with median notch or excavation (major worker yellow; vertex lobes foveolate): Pheidole anastasii
90b. Color usually brown to black, rarely yellow; head rounded behind to somewhat flattened (major worker brown or with sharply bicolored head): 100
100a Head somewhat flattened behind; scapes relatively shorter(?) (major worker brown; vertex lobes shiny): Pheidole bilimeki
100b. Head relatively more rounded behind; scapes relatively longer(?) (major worker with face sharply bicolored, brown anteriorly, yellow posteriorly): Pheidole punctatissima
110a Promesonotal suture distinctly impressed: 120
110b. Promesonotal suture weakly impressed or absent: 400
120a Face with some degree of sculpturing, which may be composed of puncta, striae, arcing carinae, or shagreening and may cover the entire face or be restricted to the anterior margins, posterior margins, or both; face never completely smooth and shining: 130
120b. Face completely smooth and shining, with at most some foveolate or striate sculpture restricted to the malar area: 180
130a Face with coarse longitudinal striae or with delicate arcing striae: 140
130b. Face partially to entirely foveolate: 160
140a Face with coarse longitudinal striae; propodeal spines present: Pheidole ectatommoides
140b. Face with delicate arcing striae; propodeal spines absent: 150
150a Color dark red brown: Pheidole innupta
150b. Color yellow orange: Pheidole alfaroi
160a Propodeal spines medium length to very long; head with nuchal collar: 170
160b. Propodeal spines short; head without nuchal collar: Pheidole biconstricta
170a Propodeal spines medium length; nuchal collar very narrow; color dark brown: Pheidole indagatrix
170b. Propodeal spines very long; nuchal collar more prominent; color yellow to dark brown: Pheidole fiorii
180b. Color red brown to black: 200
190a Nuchal collar strongly developed; propodeal spines very long (makes carton nests suspended from leaves): Pheidole fiorii
190b. Nuchal collar weakly developed; propodeal spines long to short (nests in soil): Pheidole tanyscapa
200a Propodeal spines absent or in the form of minute tubercles: 205
200b. Propodeal spines present: 210
205a Head lacking nuchal collar; scapes short (SI 118): Pheidole diana
205b. Nuchal collar strongly developed; scapes very long (SI 231): Pheidole JTL-144
210a Nuchal collar present, thin or strongly developed: 220
210b. Nuchal collar absent: 280
220a Metanotal groove very strongly developed: 230
220b. Metanotal groove less strongly developed: 240
230a Propodeal spines long: 235
230b. Propodeal spines short: Pheidole susannae
235a Setae on mesosomal dorsum clear to white: Pheidole ajax
235b. Setae on mesosomal dorsum black: Pheidole JTL-070
240a Nuchal collar strongly developed: 250
240b. Nuchal collar weakly developed: 260
250a Propodeal spines long; color usually yellow, brown in some populations: Pheidole fiorii
250b. Propodeal spines short: Pheidole chocoensis
260a Mesosoma red brown, lighter than head and gaster; pair of forward-curving setae on mesonotum: Pheidole prostrata
260b. Mesosoma brown, concolorous with head and gaster; multiple setae on mesonotum, and these not strongly curved anteriorly: 270
270a Setae on dorsal surface of hind femur erect: 273
270b. Setae on dorsal surface of hind femur appressed: 277
273a Propodeal spines short; propodeal dorsum shiny (major with scapes distinctly surpassing margin of vertex; abundant erect setae projecting from sides of head): Pheidole cocciphaga
273b. Propodeal spines longer; propodeal dorsum foveolate (major with scapes just reaching or falling short of margin of vertex; abundant erect setae projecting from sides of head): Pheidole indagatrix
277a Propodeal spines long (major with face almost entirely smooth and shining; sides of head with decumbent pilosity, without projecting hairs): Pheidole JTL-135
277b. Propodeal spines very short (major with dense foveate sculpture on most or all of face; sides of head with dense decumbent pilosity, without projecting hairs): Pheidole kukrana
280a Propodeal spines very long: Pheidole sicaria
280b. Propodeal spines smaller: 290
290a Mesonotum strongly produced as a nearly right-angle projection: 300
290b. Mesonotum less strongly produced, rounded: 310
300a Head and gaster covered with very long flexuous hairs: Pheidole sensitiva
300b. Head and gaster with sparse, short, stiff setae: Pheidole indistincta
310a Size large, WL greater than 1.2mm; propodeal spines very short: Pheidole biconstricta
310b. Size smaller, WL about 1mm or less; propodeal spines various: 320
320a Metanotal groove deeply impressed; propodeal spines short: Pheidole hirsuta
320b. Metanotal groove less deeply impressed; propodeal spines various: 330
330a Scape index less than 140: Pheidole dossena
330b. Scape index greater than 140: 340
340a Major with dense pile on first gastral tergite, lacking long erect setae: Pheidole psilogaster
340b. Major lacking dense pile on first gastral tergite, with long erect setae: Pheidole JTL-126
See also P. vafra.
400a Face with some degree of sculpturing, which may be composed of puncta, striae, or shagreening and may cover the entire face or be restricted to the margins; face never completely smooth and shining: 410
400b. Face completely smooth and shining, with at most some foveolate or striate sculpture restricted to the malar area and around the antennal insertions: 800
410a Mesosoma, including side of pronotum and katepisternum, uniformly foveolate: 420
410b. At least a small patch on side of pronotum or on katepisternum smooth and shiny, or generally rugose over much of surface: 600
420a WL about 1mm or greater; promesonotum strongly arched: Pheidole exarata
420b. WL less than 0.9mm; promesonotum variably arched: 430
430a Propodeal spines long: 440
430b. Propodeal spines shorter: 460
440a Color red brown; dorsal setae flexuous: 450
440b. Color yellow orange; dorsal setae sparse, short, stiff: Pheidole cataphracta
450a Scapes long (SI about 100): Pheidole diabolus
450b. Scapes shorter (SI about 90 or less): 455
455a Clypeus foveolate; pronotal tubercles forming right angles when viewed anteriorly: Pheidole scrobifera
455b. Clypeus smooth and shining; pronotal tubercles forming acute angles when viewed anteriorly: Pheidole caulicola
460a Promesonotum strongly and evenly arched (this is a weak character; try both lugs): 470
460b. Promesonotum lower, often with more differentiated anterior and dorsal faces: 510
470a Pronotum with pronounced humeral tubercles: Pheidole caltrop
470b. Pronotum lacking humeral tubercles: 480
480a Face strongly punctatorugose: Pheidole verricula
480b. Face uniformly foveolate or foveolate with weak rugulae: 490
490a Punctate sculpture on face and mesosoma faint; scapes long (SI about 115): Pheidole daphne
490b. Punctate sculpture well impressed; scapes shorter (SI about 105 or less): 495
495a Scapes long, SI about 105: 500
495b. Scapes short, SI about 84: Pheidole JTL-136
500a Color yellow orange: Pheidole nebulosa
500b. Color red brown; pilosity appressed on femora: Pheidole rectispina
510a Antennae 11-segmented; mesosomal profile step-like: Pheidole mendicula
510b. Antennae 12-segmented; mesosomal profile not step-like: 520
520a Face strongly punctatorugose: 530
520b. Face evenly foveolate or foveolate with faint rugulae: 540
530a Tibial pilosity of uniform length, subdecumbent, shorter than maximum width of tibia; setae on mesosomal dorsum stiff: Pheidole prolixa
530b. Tibial pilosity of variable length, with dense subdecumbent pilosity as above and longer erect setae that are longer than width of tibia; setae on mesosomal dorsum longer and more flexuous: Pheidole rectitrudis
540a Setae on mesosomal dorsum subdecumbent, abundant, somewhat wooly; promesonotum long and low: Pheidole striaticeps
540b. Setae on mesosomal dorsum erect, not wooly: 550
550a Propodeal spines relatively short; postpetiole small in dorsal view, subequal in width to petiolar node: Pheidole flavens
550b. Propodeal spines relatively longer; postpetiole relatively broader: 560
560a Size relatively larger, WL about 0.5mm or greater; color red brown; hind tibia with long erect setae in addition to subdecumbent pilosity (major vertex lobes with relatively finer foveolate sculpture): 565
560b. Size relatively smaller, WL about 0.46 or smaller; color variable; hind tibia with uniform subdecumbent pilosity, with or without long erect setae (major with vertex lobes more coarsely punctatorugose): 570
565a Size relatively smaller, WL about 0.52mm; face always uniformly foveate: Pheidole specularis
565b. Size relatively larger, WL about 0.64; face sometimes with faint rugulae over foveate sculpture: Pheidole JTL-136
570a Major with head relatively thinner dorsoventrally (seen in lateral view of head); major worker postpetiole transverse, with triangular projections: Pheidole ruida
570b. Major with head thicker dorsoventrally; postpetiole more trapezoidal in dorsal view: 580
580a Hind tibia with long erect setae in addition to shorter appressed pilosity; color variable: Pheidole JTL-143
580b. Hind tibia lacking long erect setae, with short appressed pilosity only; color lighter orange: Pheidole JTL-104
600a WL greater than 1.1mm; eye very small; mesosomal dorsum with abundant stiff black setae: Pheidole fimbriata
600b. WL less than 1.0mm; eye normal size; mesomal pilosity variable: 610
610a WL about 0.8mm or greater; promesonotum strongly arched: 615
610b. WL about 0.8mm or less, usually less than 0.7mm; promesonotum not strongly arched: 630
615a Scapes foveolate: Pheidole colobopsis
615b. Scapes smooth: 620
620a Major with strong clypeal keel: Pheidole rhinoceros
620b. Major lacking clypeal keel: Pheidole arietans
630a Scapes very long (SI greater than 120): 640
630b. Scapes shorter (SI about 100 or less): 648
640a Propodeal spines absent: 645
640b. Small propodeal spines present: Pheidole boruca
645a Color orange: Pheidole JTL-129
645b. Color dark brown: Pheidole rugiceps
648a Face and mesosoma uniformly reticulate rugose over shiny surface: Pheidole carinata
648b. Face and mesosoma at least partially foveolate: 650
650a Scapes relatively longer, SI about 100; spiracle large; color yellow: Pheidole onyx
650b. Scapes relatively shorter, SI about 90 or less; spiracle small; color various: 660
660a Face punctatorugose or smooth overlain with weak rugae: 670
660b. Face uniformly foveolate: 680
670a Propodeal spines short (major head relatively shorter, broader): Pheidole dryas
670b. Propodeal spines longer, upturned (major head relatively long and narrow): 673
673a Face smooth, overlain with weak rugae: Pheidole JTL-141
673b. Face distinctly foveate rugose: 675
675a Relatively more robust; color red brown; face more coarsely rugose (?); head relatively broader (?): Pheidole JTL-139
675b. Relatively smaller, less robust; color often lighter orange brown; face more weakly rugose; head narrower (?) (major head long and narrow): Pheidole beloceps
680a Antenna 10-segmented: Pheidole perpusilla
680b. Antenna 12-segmented: 690
690a Spiracle very large (major with very long narrow head): Pheidole christopherseni
690b. Spiracle small: 700
700a Pronotal dorsum smooth and shiny: 710
700b. Pronotal dorsum foveolate: 720
710a Color orange; promesonotum relatively shorter and more strongly arched; WL about 0.5mm: Pheidole browni
710b. Color dark brown to black; promesonotum relatively longer and less strongly arched; WL about 0.6mm: 715
715a Dorsal face of propodeum foveolate: Pheidole JTL-138
715b. Dorsal face of propodeum smooth and shining: Pheidole monteverdensis
720a Punctation on face and mesosoma faint, surface with a silky luster: Pheidole cerina
720b. Punctation on face and mesosoma normal, without silky luster: 730
730a Side of pronotum uniformly foveolate; katepisternum smooth and shiny: Pheidole hazenae
730b. At least posterior half of side of pronotum smooth and shiny; katepisternum foveolate or smooth and shiny: 740
740a Dorsal profile of promesonotum strongly flattened; lateral face of pronotum strongly sloping anteriorly to posteriorly, such that in dorsal view promesonotum is strongly angular: Pheidole otisi
740b. Dorsal profile of promesonotum not strongly flattened; lateral face of pronotum not as strongly slanted: 750
750a Size larger, WL about 0.7mm; petiolar node rounded in lateral view: Pheidole boltoni
750b. Size smaller, WL about 0.5mm; petiolar node more acute in lateral view: 760
760a When laid back, scapes surpass vertex margin (SI about 100): Pheidole olsoni
760b. Scapes just reach vertex margin (SI about 85): 770
770a Major with medial face longitudinally rugose; antennal scrobes shallow, lacking defined posterior border: Pheidole protensa
770b. Major with medial face transversely rugose; antennal scrobes well defined, with marked posterior border: Pheidole scalaris
800a Propodeal spines absent or reduced to tiny tubercles: 810
800b. Propodeal spines present: 840
810a WL about 0.8mm or greater: 820
810b. WL about 0.6mm or smaller: 830
820a Mesosoma mostly smooth and shiny: Pheidole arachnion
820b. Mesosoma mostly foveolate: Pheidole celaena
830a WL about 0.6; scapes extend beyond margin of vertex (SI about 100): Pheidole subarmata (also see Pheidole synarmata
830b. WL about 0.4mm; scapes do not extend beyond vertex margin (SI about 80): Pheidole nitella
840a Postpetiole grossly swollen, larger than petiolar node: Pheidole megacephala
840b. Postpetiole smaller, subequal in size to petiolar node: 850
850a Mesonotal suture weakly impressed; head with a narrow nuchal collar; bicolored with lighter red brown mesosoma, darker head and gaster: Pheidole prostrata
850b. Mesonotal suture completely absent; head lacking nuchal collar; color various: 860
860a Mesopleuron and propodeum coarsely reticulate rugose: Pheidole vestita
860b. Mesopleuron and propodeum variously foveolate or smooth and shiny: 870
870a Color orange; WL about 0.7mm; face and mesosoma covered with dense, short, almost wooly pilosity; specialized inhabitant of Piper ant plants: Pheidole bicornis
870b. Not exactly fitting above description: 880
880a WL about 0.45mm; propodeal spines very short: 890
880b. WL about 0.5mm or greater; propodeal spines various: 910
890a Dorsum of mesosoma with sparse, short, stiff, black setae: Pheidole nigricula
890b. Dorsum of mesosoma with flexuous, lighter-colored hairs: 900
900a Anterior pronotum with transverse carina: Pheidole laselva
900b. Anterior pronotum lacking transverse carina:: Pheidole sagittaria
910a Face with subdecumbent pilosity; scapes short (SI about 75); major worker with semiphragmotic head: Pheidole truncula
910b. Face usually with erect setae; scapes relatively longer; major worker without phragmotic head: 920
920a Promesonotum very strongly and evenly arched: 930
920b. Promesonotum less strongly arched: 970
930a Scapes foveolate: Pheidole vestita
930b. Scapes smooth: 940
940a Scapes very long, SI about 118 or greater; propodeal spines long, upturned: 945
940b. Scapes shorter, SI less than about 110; propodeal spines short: 950
945a Scapes very long, SI about 150; WL greater than 0.9mm: Pheidole JTL-112
945b. Scapes shorter, SI about 118; WL less than 0.8mm: Pheidole JTL-133
950a Pilosity on mesosomal dorsum short, sparse, stiff: Pheidole excubitor
950b. Pilosity on mesosomal dorsum abundant, flexuous: 960
960a Major with longitudinal keel on clypeus (I cannot tell minor workers of arietans, prattorum, and rhinoceros apart): 965
960b. Major lacking keel on clypeus: 967
965a Major face red brown to orange; posterior portion of shallow antennal scrobe reticulate rugose: Pheidole prattorum
965b. Major face red brown to dark brown; posterior portion of shallow antennal scrobe areolate to smooth and shining, longitudinal rugae on anterior half of scrobe but not extending onto posterior half: Pheidole rhinoceros
967a Webers length about 0.6mm; scapes when laid back just reach margin of vertex: Pheidole synarmata
967b. Webers length about 0.6mm; scapes when laid back surpass margin of vertex: Pheidole JTL-137
967c. Webers length about 0.8mm; scapes distinctly surpass margin of vertex: Pheidole arietans
970b. Color red brown to black: 1000
980a WL greater than about 0.8mm: Pheidole amabilis
980b. WL about 0.7mm or less: 990
990a Propodeal spines relatively short; major with anterior portion of head dark: Pheidole nasutoides
990b. Propodeal spines longer; major with head concolorous orange: Pheidole citrina
990c. Propodeal spines short; major with head concolorous orange to dusky brown, relatively more elongate, subrectangular: Pheidole nitidicollis
990d. Propodeal spines short; promesonotum relatively more smooth and shining than others; major with head concolorous orange, broadly cordate: Pheidole ulothrix
1000a Scapes long, SI about 100 or greater: 1010
1000b. Scapes shorter, SI about 90 or less: 1020
1010a Propodeal spines very long: Pheidole simonsi
1010b. Propodeal spines shorter: 1015
1015a Propodeal spines relatively spiniform (major with face mostly covered with sculpture; hypostomal margin strongly concave between medial pair of strong teeth): Pheidole JTL-130
1015b. Propodeal spines relatively triangular (major with face largely smooth and shining; hypostomal margin weakly concave across entire length): Pheidole erratilis
1020a Propodeal spines relatively longer: 1030
1020b. Propodeal spines short, upturned: 1040
1030a Major head much longer than wide, CI about 80: Pheidole cramptoni
1030b. Major head about as long as wide, CI about 95: Pheidole tennantae
1040a Pronotal dorsum foveolate; major with longitudinal keel on clypeus: Pheidole nitidicollis
1040b. Pronotal dorsum smooth and shiny; major lacking keel on clypeus: 1050
1050a Spiracle large, appearing nearly contiguous with base of propodeal spine: Pheidole arboricola
1050b. Spiracle smaller, more distant from base of spine: 1060
1060a Size small, WL about 0.6mm; major with hypostomal margin straight, with no median tooth, and pair of small teeth about half distance to recessed teeth flanking mandible bases: Pheidole JTL-092
1060b. Size larger, WL about 0.7mm or greater; major with hypostomal margin gently to strongly curved, median tooth present, pair of teeth adjacent to median tooth stout: 1070
1070a Pronotal humeri with moderately developed tubercles; major with strongly curved hypostomal margin, median tooth smaller than pair of adjacent teeth: Pheidole JTL-130
1070b. Pronotal humeri rounded; major with weakly curved hypostomal margin, median tooth nearly equal in size to pair of adjacent teeth: Pheidole umphreyi
Page author:
John T. Longino, The Evergreen State College, Olympia WA 98505 USA.longinoj@evergreen.edu
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