DACETINI, Forel, 1892

Jeffrey Sosa-Calvo, Ted R. Schultz & John S. Lapolla, 2010, A Review of the Dacetine Ants of Guyana (Formicidae: Myrmicinae), Journal of Hymenoptera Research 19, No. 1, pp. 11-43 : 39-43

KEY TO DACETINI KNOWN FROM GUYANA

(NOTE: This key is an adaptation of that of Bolton [2000] to include only the species that occur in Guyana. This key also includes modifications from Brown and Kempf [1969]; Bolton [1994])

1. Antenna 11–segmented............................................... 2

– Antenna 4 to 6–segmented............................................. 6

2(1). In lateral view, antennal scape passes below eye when in resting position. Propodeal node bidentate. Palpal formula 5,3...................... Daceton armigerum

– In lateral view, antennal scape passes above eye when in resting position. Propodeal node unarmed. Palpal formula 0,1.................................... 3

3(2). Preapical area of masticatory margin of mandibles with irregular denticles................................................. Acanthognathus brevicornis

– Preapical area of masticatory margin of mandibles lacking denticles............. 4

4(3). Node of petiole with convex anterior face and flat, sloping posterior face, not evenly rounded.................................... Acanthognathus stipulosus

– Node of petiole low and evenly rounded when seen in profile................. 5

5(4). Fossae on posterior half of dorsum of head smaller, mostly separated by flat, smooth spaces....................................... Acanthognathus ocellatus

– Fossae on posterior half of dorsum or head large, mostly contiguous or separated by single, simple longitudinal rugulae................... Acanthognathus lentus

6(1). Mandibles inserted on sides of anterior cephalic margin and converging towards apex when closed. Inner margin of mandibles generally with numerous teeth or denticles............................................... 7 ( Pyramica )

– Mandibles inserted on median portion of anterior cephalic margin and diverging towards apex when closed. Inner margin of mandibles with 0–2 preapical teeth............................................... 25 ( Strumigenys )

7(6). In full-face view, mandibles sublinear to linear, elongated and narrow; when closed, mandibles contacting each other only in apical halves or less of their lengths; either with an elongate space between mandibles or their inner margins convex so that margins touch, or nearly touch, near midlength.......................... 8

– In full-face view, mandibles either short and trap-like, or triangular to elongatetriangular; when closed contacting through most or all of their exposed length, lacking an elongate space between mandibles or at most with diastema basally between basal lamella and basal tooth................................. 15

8(7). Disc of postpetiole smooth or with weak longitudinal costulae in parts, never densely reticulate-punctate................................... Pyramica dahlanae

– Disc of postpetiole densely reticulate-punctate over most or all of its surface...... 9

9(8). Inner margin of mandible with clearly defined submedian tooth or distinctly enlarged denticle at or just distal of midlength of mandible, this tooth or denticle obviously larger than any other preapical dentition that may be present distal to it, if two distinctive enlarged teeth present, distal located at about the apical third and proximal in basal third of mandible length. Labral lobes very long and slender, trigger hairs at apices of lobes short.................................. 10

– Inner margin of mandible without a tooth or distinctly enlarged denticle at or near the midlength that is obviously larger than any other preapical dentition that may be present distal to it, if two distinctive enlarged teeth present, both of them closer to preapical dentition than to midlength of mandible. Labral lobes short, trigger hairs at apices of lobes long............................................. 13

10(9). Pronotal humeral hair long and flagellate. Mesonotum with single pair of long flagellate hairs....................................... Pyramica metopia

– Pronotal humeral hair sometimes absent usually present, short-spatulate to filliform, never flagellate. Mesonotum without flagellate hairs...................... 11

11(10). Scape narrow basally; anterior margin of scape beyond base abruptly expanded and almost lobate at subbasal angle, scape distinctly widest at this point. Dorsolateral margin of head lacking apicoscrobal hair. Postpetiole, in profile, swollen or subglobular...................................... Pyramica crassicornis

– Scape gradually broadening from base to apex; anterior margin convex but not abruptly expanded at subbasal angle, scape widest at or near its midlength. Dorsolateral margin of head with an apicoscrobal hair of some form. Postpetiole, in profile, not swollen nor subglobular.................................. 12

12(11). Inner margin of mandible with single enlarged preapical tooth, located near midlength; other minutely denticles present, but without a second equally sized tooth. Larger species (HL 0.61–0.63, HW 0.41–0.43, AL 0.58–0.60)............ Pyramica stenotes

– Inner margin of mandible with two enlarged preapical teeth of approximately equal size; in addition to other minutely denticles. Smaller species (HL 0.50–0.52, HW 0.34–0.36, AL 0.46–0.50)............................... Pyramica auctidens

13(9). In lateral view, dorsum of mesosoma with 4–6 pair of stout remiform standing hairs (not including those at humeri). Mandibles short (MI 49–54). In full-face view, inner margins of mandibles convex and, when entirely closed, touching at about midlength....................................... Pyramica subedentata

– In lateral view, dorsum of mesosoma with single pair of standing hairs (not including those at humeri). Mandibles larger (MI 72–85). In full-face view inner margins of mandibles more or less straight to shallowly concave..................... 14

14(13). Inner margin of mandibles with 5–10 preapical denticles of similar size. Metapleuron entirely densely reticulate. Peduncle of petiole short, PI 38–42... Pyramica denticulata

– Inner margin of mandibles with 3–4 preapical denticles, two of which are distinctly much larger than rest. Metapleuron in most of its surface smooth and shining. Peduncle of petiole elongate, PI 48–49...................... Pyramica mariae

15(7). With head in full-face view, anterior margin of scape with projecting curved hairs, of which one or more, distal to subbasal bend, distinctly curve toward base of scape. These hairs may be simple, spatulate, spoon-shaped, or wire-like............ 16

– With head in full-face view, anterior margin of scape without projecting hairs that distinctly curve toward base of scape. Scape edge may have elongate simple straight or flagellate projecting hairs present; or may have entirely anteriorly or apically directed short hairs; or lacking hairs........................... 21

16(15). Pronotal humeral hair present, may be filiform, flagellate, remiform, or clavate; humeral hair always distinctly differentiated from any other pilosity that may be present on dorsal pronotum........................................ 17

– Pronotal humeral hair absent; humerus without a hair that is distinctly differentiated from any other pilosity that may be present on dorsal pronotum............ 20

17(16). Ventral surface of petiole in profile with spongiform tissue reduced to absent; discounting anterior subpetiolar process (if present) usually with narrow nonspongiform cuticular carina, but if weakly spongiform strip occurs then its maximum depth only fraction of depth of peduncle. Disc of postpetiole usually sculptured at least in part, only rarely mostly smooth..................... 18

– Ventral surface of petiole in profile with deep, conspicuous and very obviously spongiform curtain, its maximum depth at least half that of peduncle and usually more. Disc of postpetiole completely unsculptured and glassy smooth............ Pyramica alberti

18(17). Metapleuron and side of propodeum entirely reticulate-punctate.............. 19

– Metapleuron and side of propleuron mostly or entirely smooth and shinning.................................................... Pyramica cincinnata

19(18). Pronotal humeral hair elongate and freely projecting, slightly flattened apically and more or less straight. Scape in dorsal view slender, broadest point distinctly distal of midlenght. Anterior margin of clypeus very shallowly convex in full-face view. Disc of postpetiole not entirely densely reticulate-punctate..... Pyramica urrhobia

– Pronotal humeral hair very short, clavate. Scape in dorsal view broad and flattened, broadest point proximal of midlenght, at or just distal of subbasal bend. Anterior margin of clypeus transverse to very shallowly concave in full-face view. Disc of postpetiole entirely densely reticulate-punctate............... Pyramica metrix

20(16). Promesonotum, side of mesosoma, and disc of postpetiole finely reticulate-punctate. Head in profile incredible dorsoventrally flattened; at eye level depth of head capsule scarcely more than twice vertical diameter of the eye. Ventral margin of petiole lacking curtain of lamellate or spongiform tissue.... Pyramica depressiceps

– Promesonotum and side of mesosoma smooth and shining, disco of pospetiole not reticulate-punctate. Head in profile not strongly dorsoventrally flattened; at eye level depth of head capsule distinctly more than twice vertical diameter of eye. Ventral margin of petiole with lamellate curtain that extends entire length of segment............................................ Pyramica thaxteri

21(15). With head in full-face view dorsolateral margin behind level of eye with laterally projecting hairs present; at least an apicoscrobal hair but often more along margin............ 22

– With head in full-face view dorsolateral margin behind level of eye without laterally projecting hairs of any form; any hairs that do occur are minute and closely appressed, not at all projecting...................................... 24

22(21). Midline of clypeal dorsum raised into a high-arched thick longitudinal crest that extends entire length of sclerite. With postpetiole in profile ventral spongiform lobe either completely absent or reduced to minute triangular vestige anteriorly on sternite........................................... Pyramica inusitata

– Midline of clypeal dorsum not raised into a high longitudinal crest that extends length of sclerite. With postpetiole in profile ventral spongiform lobe fully developed, basally extending length of sternite and conspicuously convex apically....... 23

23(22). Dorsal surface of petiole without erect cuticular lamella on peduncle and anterior face of node. Dorsolateral margin of propodeum without an erect lamella on each side; lamella on propodeal declivity narrow to cariniform, in profile its maximum width much less than length of postpetiole disc.................. Pyramica villiersi

– Dorsal surface of petiole with erect cuticular lamella that extends along peduncle and ascends anterior face of node, terminating just behind anterodorsal angle. Dorsolateral margin of propodeum with a tall erect cuticular lamella on each side that is continuous with extremely broad lamella on declivity; in profile maximum width of lamella on declivity equal to length of postpetiole disc................... Pyramica mirabilis

24(21). Dorsal outline of clypeus angled down at about 45 degrees to line of vertex. Ventral surface of petiole with well-developed curtain, of spongiform or translucent lamellar tissue, that runs most or all of the length of the segment. Head elongate (CI 68–70).............................................. Pyramica beebei

– Dorsal outline of clypeus not angled down from line of vertex. Ventral surface of petiole lacking curtain of spongiform or lamellar tissue. Head short and broad (CI 91–96).......................................... Pyramica glenognatha

25(6). Anterior margin of scape with all hairs curved or inclined toward apex of scape, without hairs that curve toward base of scape, and without a series of hairs at rightangles to long axis of scape shaft.................................... 26

– Anterior margin of scape either with one to many hairs that distinctly curve toward base of scape, or rarely with hairs that are at right angles to long axis of scape shaft; never with all hairs obviously curved or inclined toward apex of scape....... 29

26(25). Mandibles relatively short, MI <75. Bulla of femoral gland located in apical quarter of dorsum of each leg; each bulla usually appears as pale oval patch, less commonly as short streak................................................... 27

– Mandibles relatively long MI> 85. Bulla of femoral gland located close to midlength on dorsum of each leg; each bulla appears as pale elongate streak or as oval patch... 28

27(26). Mandibles short and stout (MI 41–48), broad and powerful, outer margins strongly bowed outwards. Declivity of propodeum in profile with tooth or spine above and triangular lobe or tooth below, two linked by lamella. First gastral tergite glassy smooth behind minute to vestigial basigastral costulae..... Strumigenys godmani

– Mandibles long and linear (MI 57–60), thick throughout most of their length and abruptly narrowing just before apex by sudden oblique divergence of inner margin, outer margins straight to slightly convex. Declivity of propodeum in profile with single tooth or spine, lacking second tooth or lobe below. First gastral tergite finely reticulate-substrigulate with some verrucose sculpture confined to basigastral area................................................ Strumigenys royi

28(26). In full-face view distal preapical tooth of mandible is closer to proximal preapical tooth than it is to apicodorsal tooth................ Strumigenys dolichognatha

– In full-face view distal preapical tooth of mandible is closer to apicodorsal tooth than it is to proximal preapical tooth...................... Strumigenys cordovensis

29(25). Mandible without intercalary teeth or denticles that arise between apicodorsal and apicoventral teeth, nor that arise from dorsal base of apicoventral tooth....... 30

– Mandible with 1 or 2 intercalary teeth or denticles that arise between apicodorsal and apicoventral teeth, or that arise from dorsal base of apicoventral tooth........ 40

30(29). Mandible without preapical teeth or denticles............................. 31

– Mandible with 1 or 2 preapical teeth or denticles.......................... 32

31(30). Hairs of first gastral tergite flagellate, not flattened and ribbon-like through most of their length...................................... Strumigenys elongata

– Hairs of first gastral tergite flattened and ribbon-like through most of their length, narrowly flagellate only in apical section............... Strumigenys pariensis

32(30). Mandibles very long, MI> 100......................... Strumigenys trudifera

– Mandibles much shorter, MI <75...................................... 33

33(32). With head in profile preocular carina extends back almost to apex of scrobe, well beyond level of minute eye. Bulla of femoral gland proximal of midlength on dorsum of middle leg, very conspicuous. Scape relatively long, SI 111-112..................................................... Strumigenys smilax

– With head in profile preocular carina terminates at level of eye. Bulla of femoral gland distal of midlength on dorsum of middle leg or inconspicuous. Scape shorter, SI <100........................................................... 34

34(33). Large species (HL 0.86–1.02, ML 0.50–0.56, AL 0.80–1.00). Ventrolateral margin of head in front of eye, and side of head above it, deeply concave; margin and side appear excavated or constricted in oblique dorsal view........... Strumigenys precava

– Smaller species (HL 0.39–0.45, ML 0.20–0.30, AL 0.36–0.47). Ventrolateral margin of head in front of eye, and side of head above it, not deeply concave; margin and side do not appear excavated or constricted in oblique dorsal view.............. 35

35(34). In full-face view upper scrobe margin with row of 4–5 broadly spatulate to spoon-shaped hairs that curve posteriorly.................... Strumigenys perparva

– In full-face view upper scrobe margin with row of simple, or narrowly spatulate to spoon-shaped hairs that all curve anteriorly............................ 36

36(35). Mandible with single spiniform preapicaltooth, in distal third, or with tooth in this position and denticle, that may be minute and difficult to see, close to midlength... 37

– Mandible with minute inconspicuous denticle close to midlength lacking second tooth of any form........................................ Strumigenys acarai

37(36). Leading edge of antennal scape with spoon-shaped or spatulate hairs. In full-face view upper scrobe margin with row of spatulate to spoon-shaped hairs, and with apicoscrobal hair only. Cephalic ground-pilosity spoon-shaped or spatulate.... 38

– Leading edge of antennal scape with narrowly spatulate or simple hairs. In full-face view upper scrobe margin with row of simple hairs and with two flagellate hairs, one of which is apicoscrobal hair. Cephalic ground-pilosity multi-furcate..................................................... Strumigenys waiwai

38(37). Hairs on first gastral tergite short and stout, broadly spatulate or remiform; elongate slender fine hairs absent or restricted to transverse row at extreme apex of sclerite.......................................... Strumigenys silvestrii

– Hairs on first gastral tergite elongate and slender, finely filiform to flagellate, or flexuous; short stout spatulate or remiform hairs entirely absent............ 39

39(38). Mandibles relatively long, MI> 60. Disc of postpetiole smooth and shinning. Mesonotum without pair of erect flagellate hairs.......... Strumigenys dyseides

– Mandibles relatively short, MI <60. Disc of postpetiole densely punctate to reticulate-punctate. Mesonotum with pair of erect flagellate hairs........ Strumigenys ruta

40(29). Apical fork of mandible with single intercalary tooth or denticle that arises between apicodorsal and apicoventral teeth, or arises from dorsal surface of apicoventral tooth........ 41

– Apical fork of mandible with two intercalary teeth or denticles that arise between apicodorsal and apicoventral teeth; frequently represented by distinct intercalary tooth accompanied by less conspicuous or minute denticle....... Strumigenys cosmostela

41(40). First gastral tergite very finely and densely longitudinally striolate-costulate and opaque. Apicoscrobal hair, pronotal humeral hair and standing hairs on mesonotum all flagellate. Entire body dull yellow to brownish-yellow, gaster not contrasting with head and alitrunk................. Strumigenys trinidadensis

– First gastral tergite glassy smooth. Apicoscrobal hair, pronotal humeral hair and standing hairs on mesonotum all stiff, simple to weakly remiform. Head and alitrunk reddish brown to brown, gaster blackish brown to black, both contrasting........................................ Strumigenys smithii