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The genus Pachycondyla in Costa Rica

This key relies heavily on the character systems and structure developed by the late W. L. Brown, Jr. Every couple of years he would produce a new version of his New World Pachycondyla key, a few photocopies of which would escape and proliferate among myrmecologists (in spite of his warnings about its provisional nature). In a way, his system of photocopies with periodic upgrades, distasteful though it was to him, presaged Web-based documents such as this one. They are live, in-progress documents, subject to change, yet still very useful to myrmecologists.

10a. Extensor surfaces of mid-tibiae with stiff, conical setae set over at least 1/2 of their length (figure); yellowish in color; eyes absent; mandibles sublinear, oblique masticatory border continuous with basal border: guianensis

10b. Extensor surfaces of mid-tibiae without stiff, conical setae, though long, fine erect setae may occur; orange to black in color; eyes small or large but distinctly present and multifacetted; mandibles usually triangular, with basal and masticatory borders meeting at a distinct angle (but not in the common tramp species stigma): 20

20a. Large black ants with dorsum of mesosoma and propodeum devoid of erect hairs; body surface sericeous; active surface foragers with rapid, nervous, wasp-like behavior: 30

20b. Dorsum of mesosoma and propodeum with erect hairs; size, color, and body surface various; behavior not nervous and wasp-like: 50

30a. Tips of antennae bright yellow; posterolateral margins of petiole feebly margined (apicalis and verenae are remarkably similar species, but are broadly sympatric and occur together in forested habitats): apicalis

30b. Tips of antennae brown; posterolateral margins of petiole distinctly, although not sharply, margined: verenae

50a. Opening of propodeal spiracle viewed perpendicularly small and round: 60

50b. Opening of propodeal spiracle viewed perpendicularly slit-shaped, more than twice as long as wide (spiracle may be very small, and boss around spiracle may be round, but actual orifice still slit-shaped): 100

60a. Clypeus truncate anteriorly; posteroventral margin of petiole with flat, posteriorly directed flange that extends almost to posterior margin of petiole: 63

60b. Clypeus subtriangular anteriorly; ventral margin of petiole with anteroventral lobe which may be square-cut posteriorly, but without a posteriorly projecting flange: 70

63a. Base of mandible with pronounced curving sulcus; petiolar node cuboidal in side view, not tapering dorsally: 65

63b. Base of mandible with sulcus indistinct or absent; petiolar node often more tapered dorsally: 67

65a. Surface of mandible striate; sides of head with no or very sparse erect setae; petiole relatively broad in side view: panamensis

65b. Surface of mandible smooth and shining; sides of head with abundant erect setae; petiole relatively narrower in side view: JTL-018

67a. Mandibles striate; pubescence of third abdominal tergite relatively dense, scruffy; often with short erect setae on hind tibia; head width variable; nests under dead wood or stones on the ground: 68

67b. Mandibles smooth and shining or very faintly striate; pubescence of third abdominal tergite relatively dilute, shorter; hind tibia with no erect setae; head width 1.28-1.41mm; nests under epiphytes: JTL-014

68a. Petiole in side view cuboidal, with parallel anterior and posterior faces; head width 1.08mm (n=1): JTL-017

68b. Petiole in side view tapering dorsally; head width variable: 69

69a. Petiole less tapering in side view; size smaller, head width about 0.90mm; color lighter orange brown: JTL-016

69b. Petiole more tapering; size larger, head width about 1.07mm; color darker red brown: JTL-015

70a. Propodeal suture deeply impressed; scapes extend far beyond vertex margin: constricta

70b. Propodeal suture not deeply impressed; scapes barely reach vertex margin: 75

75a. Ventral petiolar process with a low, square-cut posterior margin; sides of head lacking erect setae; dorsal and lateral faces of pronotum separated by a feeble, rounded margin: arhuaca

75b. Ventral petiolar process broadly convex, posterior margin rounded; sides of head with projecting erect setae; dorsal and lateral faces of pronotum continuous, not differentiated: 80

80a. Anteromedian margin of clypeus with a short spine: becculata

80b. Anteromedian margin of clypeus triangular, lacking spine: pergandei

100a. Black; very smooth and shining, forming a highly polished, reflective surface over most of body: laevigata

100b. Color various; body never strongly shining over most of surface; surface largely mat with various degrees of punctation or striation: 110

110a. Mandible with 6-8 teeth; head width less than 1.3mm; petiole scale-shaped, tapering dorsally to rounded summit (stigma complex): 120

110b. Mandible with 9 or more teeth; head width usually greater than 1.3mm; petiole shape various: 200

120a. Lateral wings of clypeus divided by distinct transverse ridge, anterior portion distinctly concave and bent ventrad; in lateral profile, posterior margin of anteroventral petiolar lobe subangular to square-cut or even slightly produced as a subacute angle; mandible with 6 or 7 teeth (non-tramp species of mature forest habitats): 130

120b. Lateral wings of clypeus almost smoothly convex, transverse ridge very weak, anterior portion flat to weakly concave, not as strongly bent ventrad as above; in lateral profile, posterior margin of anteroventral petiolar lobe broadly rounded; mandible with 6 teeth, basal and masticatory margins not well-differentiated (common tramp species in disturbed areas; less often in mature forest): stigma

130a. Frontal carinae not closely approximated where they accomodate scapes, ratio of greatest distance between frontal carinae (across frontal lobes) to smallest distance 2.5: 140

130b. Frontal carinae closely approximated, ratio of greatest distance between frontal carinae to smallest distance 5.5: cognata

140a. Mandible usually with 6 teeth, basal and masticatory margins not well-differentiated: cauta

140b. Mandible with 7 or 8 teeth, basal and masticatory margin relatively more differentiated: JTL-011

200a. In side view, dorsal outline of mesosoma forms a continuous convexity including mesonotum, metanotum and propodeal dorsum; propodeal groove obsolete or nearly so, and not strongly impressed; pronotal dorsum usually with strong, lateral margins: 210

200b. Dorsal outline of mesosoma interrupted by a distinct, impressed propodeal groove, so that the mesonotum forms a convexity separate from the more or less convex propodeal dorsum; lateral margins of pronotal dorsum distinct, indistinct, or absent: 350

210a. A distinct carina runs from the lateral wing of the clypeus near the mandibular insertion to or nearly to the anteromesal quarter of the margin around the eye; acrotergite of second gastral tergum (when exposed) with a distinctly differentiated median stridulatory file with bands of rainbow colors; arolia present (figure): 220

210b. Cheeks without a distinct carina reaching more than halfway from clypeal wing to eye margin (a carina indistinct from the background sculpture may sometimes occur); stridulatory file absent; arolia absent: 300

220a. Petiolar node as seen from the side with front face rising abruptly to an angular summit at or near the front, from which it descends behind through a broad curve: 230

220b. Petiolar node as seen from the side with a horizontal or strongly rounded summit with highest point near nodal midlength; or else the apex rises well behind midlength: 250

230a. Posterior face of petiolar node densely and finely punctulate, not striate: unidentata complex

230b. Posterior face of petiolar node coarsely transversely striate over most or all of surface: striatinodis

250a. Petiolar node as seen from the side more or less subquadrate, with vertical anterior and posterior faces and a horizontal but convex dorsal face: 255

250b. Petiolar node as seen from the side with anterior and posterior faces strongly converging above to form a sharply rounded summit near midlength: carinulata

255a. Color orange; antennal scapes when laid back just reach margin of vertex; size smaller: crenata

255b. Color black; antennal scapes long, distinctly surpassing margin of vertex; size larger: JTL-013

300a. Head width less than 2.0mm; mesosoma less than 3.6mm long; dorsolateral margin of pronotum often with a distinct carina (figure): harpax complex

300b. Head width greater than 2.0mm; mesosoma greater than 3.6mm long; dorsolateral margin of pronotum uniformly punctate, rounded: 320

320a. Clypeus narrow front to back, with deep median notch that extends almost to anterior margins of frontal lobes: impressa

320b. Clypeus broader front to back, anterior margin truncate, flattened to weakly notched, but with medial margin well in front of frontal lobes: purpurascens

350a. In full-face view, a line drawn through the centers of the eyes falls near mid-head, crossing near posterior limits of frontal carinae; cheeks usually with a distinct carina reaching from clypeal wing to eye margin: 360

350b. Eyes situated more anteriorly on head, such that a line drawn through the centers of the eyes crosses the frontal carinae near their greatest constriction; cheeks without a distinct carina reaching from clypeal wing to eye margin (montane species): aenescens

360a. Anterior face of petiolar node somewhat sloping to rounded apex: 365

360b. Anterior face of petiolar node more perpendicular, forming a more angular anterodorsal summit: 370

365a. Dorsolateral margins of petiole absent; slender species with posterior margin of head straight to feebly convex in full-face view; antennal scapes long, SI greater than 120: dismarginata

365b. Dorsolateral margins of petiole present; posterior margin of head broadly and strongly convex; antennal scapes relatively shorter, SI less than 120: JTL-012

370a. Center of vertex convex, covered with very coarse, diverging-longitudinal striation, free of pubescence, shining and contrasting strongly with the surrounding areas of fine sculpture and pubescence; center of posterior face of node usually coarsely vertically rugose: lineaticeps

370b. Vertex with sculpture and pubescence like most of remaining dorsum of head, punctulate or finely striate; posterior face of node sculptured differently -- transversely striate or with indefinitely oriented rugosity or punctulae: 380

380a. Posterior face of petiolar node coarsely, transversely striate to apex; head width including eyes greater than 2.0mm: foetida

380b. Upper half of posterior face of petiolar node finely punctulate or otherwise sculptured, not transversely striate; other characters various: 390

390a. Sides of petiolar node longitudinally striate or rugulose on the lower half or more; often irregularly striate or rugulose on lower part of posterior face as well: theresiae

390b. Sides of node finely punctulate, surface weakly shining: 400

400a. Anteromedian portion of clypeus transversely rugose: insignis

400b. Anteromedian portion of clypeus smooth or longitudinally striatorugose: 410

410a. Larger, more robust species, head width including eyes usually greater than 2.2mm, width of pronotum greater than 1.55mm: villosa

410b. Smaller and more slender species, head width including eyes usually less than 2.2mm, width of pronotum less than 1.55mm: bugabensis

Page author:

John T. Longino, The Evergreen State College, Olympia WA 98505 USA.longinoj@evergreen.edu

Date of this version: 27 April 2006.
Previous versions of this page: 3 April 1999
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