Key to Strumigenys of East Asia

This worker key is based on: Bolton, B. 2000. The ant tribe Dacetini. Memoirs of the American Entomological Institute. 65:1-1028.

Malasian-Oriental-East Palaearctic Strumigenys

Bolton noted: Note. The Tongan Strumigenys zakharovi (species inquirenda) is not included in the key.

This key is from a study that included the now synonymized genus Pyramica. Therefore there are two sets of keys for the Strumigenys species from this region: the key found below and this second key for the species once classified as Pyramica: and a key Key to Strumigenys of East Asia (as Pyramica).

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 * Strumigenys

1

 * Antenna with 4 segments; first funicular segment not separated from the 2-segmented apical club . . . . . 2


 * Antenna with 6 segments; first funicular segment separated from the 2-segmented apical club by two small segments . . . . . 6

2
return to couplet #1
 * Pronotal humeral hair absent . . . . . 3


 * Pronotal humeral hair present, stiff and simple . . . . . 4

3
return to couplet #2
 * Leading edge of scape expanded into a massive projecting lobe, the area of which is much greater than the area of the median portion of the clypeus; SL at most 1.60 times the maximum scape width. Apical segment of antenna not spindle-shaped, broad basally where it articulates with preapical segment. (Indonesia (Sulawesi, Kai Besar), Papua New Guinea, Solomon Is) . . . . . Strumigenys eurycera


 * Leading edge of scape shallowly convex, not expanded into a massive projecting lobe that is greater in area than median portion of clypeus; SL 5.00 times the maximum scape width. Apical segment of antenna spindle-shaped, very constricted and narrow basally where it articulates with preapical segment. (Papua New Guinea) . . . . . Strumigenys pharosa

4
return to couplet #2
 * Basal half of first gastral sternite unsculptured. Cephalic dorsum with numerous orbicular hairs, without erect simple hairs. Leading edge of scape with short spatulate or spoon-shaped hairs that are shorter than maximum width of scape. (Pantropical tramp species) . . . . . Strumigenys emmae

5
return to couplet #5
 * Pronotum and mesonotum each with a single pair of short erect hairs. With head in full-face view dorsolateral margin with only 2-3 laterally projecting stiff hairs. Mesopleuron partly smooth. (Papua New Guinea) . . . . . Strumigenys quattuor


 * Pronotum and mesonotum each with numerous short erect hairs. With head in full-face view dorsolateral margin with more than 5 laterally projecting stiff hairs. Mesopleuron entirely reticulate-punctate. (Papua New Guinea) . . . . . Strumigenys tetra

6
return to couplet #1
 * With petiole in profile the ventral surface without any trace of a longitudinal spongiform or laminate crest, lamella or curtain . . . . . 7


 * With petiole in profile the ventral surface with a longitudinal spongiform or laminate crest, lamella or curtain present; may be narrow or sometimes reduced to a small lobe or narrow strip beneath the node . . . . . 16


 * Basal half of first gastral sternite longitudinally costulate. Cephalic dorsum with numerous short erect simple hairs, without orbicular hairs. Leading edge of scape with simple curved hairs that are longer than maximum width of scape . . . . . 5

7
return to couplet #6
 * Postpetiole in profile with ventral spongiform lobe large and well developed; lobe broadly triangular to broadly rounded and at least equal in size to the exposed cuticle of the disc . . . . . 8


 * Postpetiole in profile with ventral lobe vestigial to absent; when vestigially present the lobe not broadly triangular nor broadly rounded and very much smaller than the exposed cuticle of the disc . . . . . 9

8
return to couplet #7
 * Head, alitrunk and disc of postpetiole smooth and shining. In full-face view ventrolateral margin of head deeply excavated immediately in front of the eye. Declivity of propodeum with a broad lamella, its posterior (free) margin convex. Basigastral costulae short, restricted to zone immediately behind limbus. Head broad, scape shorter; CI 95, SI 55. (Indonesia (Sulawesi)) . . . . . Strumigenys zapyx


 * Head, alitrunk and disc of postpetiole reticulate-punctate. In full-face view ventrolateral margin of head not excavated immediately in front of the eye. Declivity of propodeum with a narrow carina, its posterior (free) margin concave. Basigastral costulae long, extending over the basal half of the tergite. Head narrow, scape longer; CI 70, SI 82. (Papua New Guinea) . . . . . Strumigenys wilsoni

9
return to couplet #7
 * With alitrunk in dorsal view pronotum and anterior mesonotum black or blackish brown, propodeal dorsum and usually also posterior portion of mesonotum yellow, the two colour zones strongly contrasting . . . . . 10


 * With alitrunk in dorsal view entire surface more or less uniformly coloured yellow, brown or black, without strongly contrasting zones of black and yellow . . . . . 12

10
return to couplet #9
 * Ventrolateral margin of head deeply notched or impressed immediately in front of eye, the notch or impression continued onto the ventral surface of the head as a transverse preocular groove or impression that extends toward, but does not reach, the midline . . . . . 11


 * Ventrolateral margin of head not deeply notched or impressed immediately in front of eye; the ventral surface of the head without a transverse preocular groove or impression that extends toward the midline. (Papua New Guinea) . . . . . Strumigenys yasumatsui

11
return to couplet #10
 * Petiole and postpetiole black. Petiole in profile with anterior face of node meeting dorsum in a long shallow convexity, the dorsum much longer than the anterior face. (Papua New Guinea) . . . . . Strumigenys tigris


 * Petiole and postpetiole yellow. Petiole in profile with anterior face of node meeting dorsum in a blunt angle, the dorsum only slightly longer than the anterior face. (Indonesia (Irian Jaya), Papua New Guinea) . . . . . Strumigenys hemichlaena

12
return to couplet #9
 * Propodeal teeth absent in profile, the angle between dorsum and declivity unarmed or with a pair of minute blunt tubercles; in dorsal view the tubercles much shorter than the distance separating them. (Papua New Guinea) . . . . . Strumigenys disarmata


 * Propodeal teeth or spines conspicuous in profile, narrowly triangular and acute; in dorsal view the teeth equal to or greater in length than the distance separating them . . . . . 13

13
return to couplet #12
 * Head, alitrunk and waist segments yellow to light yellow-brown everywhere; gaster may be same shade or darker . . . . . 14


 * Head, alitrunk and waist segments black to blackish brown everywhere; gaster also black or blackish brown. (Papua New Guinea) . . . . . Strumigenys nigra

14
return to couplet #13
 * Side of alitrunk completely smooth and shining, without trace of reticulate-punctate sculpture. (Papua New Guinea) . . . . . Strumigenys lancea


 * Side of alitrunk almost entirely reticulate-punctate, at most with a smooth patch on katepisternum . . . . . 15

15
return to couplet #14
 * Hairs of apical row on first gastral tergite and hairs on second gastral tergite flagellate, contrasting with the straight stiff hairs on the postpetiole. Propodeal spines long and slender, twice as long as the distance between their bases. Larger species, HL > 1.00. (Indonesia (Kai Besar), Papua New Guinea, Palau) . . . . . Strumigenys stemonixys


 * Hairs of apical row on first gastral tergite and hairs on second gastral tergite simple, short and stiff, the same as those on the postpetiole. Propodeal spines shorter, about equal to distance between their bases or less. Smaller species, HL < 1.00. (Singapore, Philippines (Mindanao, Luzon, Mindoro, Negros), Indonesia (Sulawesi, Kai Besar, Aru, Irian Jaya), Papua New Guinea, Solomon Is, Vanuatu, Samoa, Ponape I.; also in Australia) . . . . . Strumigenys szalayi

16
return to couplet #6
 * Ventrolateral margin of head at level of eye extended outward and downward, forming an acutely triangular prominence. Eye located on dorsal surface of this prominence; acute apex of prominence extends out beyond the midlength of the eye in the form of a sharp point . . . . . 17


 * Ventrolateral margin of head at level of eye regular or with a preocular notch or impression, but not extended outward and downward as an acutely triangular prominence. Eye not located on dorsal surface of a triangular prominence and without a sharp point that extends out beyond the midlength of the eye . . . . . 19

17
return to couplet #16
 * Erect hairs on cephalic dorsum stiff and shallowly curved, apically truncated and slightly splayed or minutely bifid. (Malaysia (Sarawak)) . . . . . Strumigenys akalles


 * Erect hairs on cephalic dorsum fine, soft and flexuous, apically tapering to acute points . . . . . 18

18
return to couplet #17
 * With mandibles fully closed the proximal preapical tooth of the left mandible is longer than the distance between its base and the anterior clypeal margin. Clypeus and pronotal dorsum smooth and shining. (Malaysia (West Malaysia), Indonesia (Java)) . . . . . Strumigenys eidechthes


 * With mandibles fully closed the proximal preapical tooth of the left mandible is much shorter than the distance between its base and the anterior clypeal margin. Clypeus and pronotal dorsum finely sculptured. (Malaysia (West Malaysia, Sarawak, Sabah), Indonesia (Sumatra, Sulawesi), Philippines (Luzo)) . . . . . Strumigenys inhonesta

19
return to couplet #16
 * Apex of mandible with three short-spiniform to long-spiniform teeth arranged in a vertical or oblique series (series may be extremely oblique so that lowermost tooth has migrated onto ventral surface and appears as a ventrally-arising preapical tooth in full-face view); with 0-2 intercalary denticles or small teeth, which when present arise between apicomedian and apicoventral teeth or from dorsal surface of apicoventral tooth . . . . . 20


 * Apex of mandible with two spiniform teeth arranged in a vertical or near-vertical series; with 0-3 intercalary denticles or small teeth, which when present arise between the apicodorsal and apicoventral teeth or from dorsal surface of apicoventral tooth near its base . . . . . 35

20
return to couplet #19
 * Fully closed mandible in full-face view very broad proximally and strikingly tapered distally, obviously not linear or curvilinear. Outer margin of mandible flared outwards near base and with a strongly projecting prebasal angle. In ventral view outer margin of mandible distal of level of anterior clypeal margin abruptly changing direction . . . . . 21


 * Fully closed mandible in full-face view not very broad proximally nor strikingly tapered distally, linear or curvilinear, sometimes weakly sinuate. Outer margin of mandible not flared outwards near base, without a strongly projecting prebasal angle. In ventral view outer margin of mandible forms a more or less continuous line that does not abruptly change direction distal of level of anterior clypeal margin . . . . . 30