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

21
return to couplet #20
 * With alitrunk in dorsal view pronotal humeral hair absent . . . . . 22


 * With alitrunk in dorsal view pronotal humeral hair present, projecting laterally; hair straight, simple or clavate, may be elongate or short and stout . . . . . 24

22
return to couplet #21
 * With head in full-face view apicoscrobal hair present, very short and stubbly. Appressed hairs on first gastral tergite fine, very narrowly spatulate and inconspicuous . . . . . 23


 * With head in full-face view apicoscrobal hair absent. Appressed hairs on first gastral tergite distinctly spatulate, numerous and conspicuous. (Malaysia (Sarawak), Indonesia (Kalimantan)) . . . . . Strumigenys aechme

23
return to couplet #22
 * Postpetiole disc in dorsal view much broader than petiole node. Small species, HW ca 0.47. (Sri Lanka, India, Bhutan) . . . . . Strumigenys lyroessa


 * Postpetiole disc in dorsal view about equal to petiole node width. Larger species, HW 0.56-0.61. (Malaysia (West Malaysia)) . . . . . Strumigenys tantilla

24
return to couplet #21
 * Dorsal surfaces of pronotum and mesonotum with numerous short straight erect stubbly hairs; similar hairs also present on dorsolateral margins of mesonotum. (Indonesia (Sulawesi)) . . . . . Strumigenys dryas


 * Dorsal surfaces of pronotum and mesonotum without erect hairs; dorsolateral margins of the mesonotum either hairless or at most with 2-3 short erect hairs on each margin . . . . . 25

25
return to couplet #24
 * Scape relatively long and head narrower, SI 67-71, CI 68-71; hind femur elongate, about equal to HW. (Malaysia (Sabah)) . . . . . Strumigenys liophila


 * Scape relatively short and head broader, SI 50-57, CI 72-84; hind femur short, much less than HW . . . . . 26

26
return to couplet #25
 * First gastral tergite entirely covered with fine dense longitudinal striolate-punctulate sculpture. Eye with 7-8 ommatidia in longest row; maximum diameter of eye obviously greater than maximum width of scape. Larger species, HL 0.89-0.92, HW 0.73-0.76. (India) . . . . . Strumigenys hostilis


 * First gastral tergite un sculptured except for basigastral costulae. Eye with 3-5 ommatidia in longest row; maximum diameter of eye at most equal to maximum width of scape, usually less. Smaller species, HL 0.62-0.80, HW 0.47-0.62 . . . . . 27

27
return to couplet #26
 * Lamella on propodeal declivity very narrow in profile; at its broadest point below the level of the spiracle it is less than half the length of the propodeal tooth . . . . . 28


 * Lamella on propodeal declivity broader in profile; at its broadest point below the level of the spiracle it is distinctly more than half the length of the propodeal tooth . . . . . 29

28
return to couplet #27
 * Petiole node in dorsal view about as broad as long, not transversely rectangular. Larger black species, HL 0.77-0.80, HW 0.60-0.62. (Malaysia (West Malaysia)) . . . . . Strumigenys micrura


 * Petiole node in dorsal view much broader than long, transversely rectangular. Smaller light brown species, HL 0.65, HW 0.49. (Indonesia (Sulawesi)) . . . . . Strumigenys imantodes

29
return to couplet #27
 * Mandible in profile with preapical tooth strongly developed, broader-based and stouter than the apicodorsal tooth; dorsal margin of mandible depressed distal of preapical tooth so that space between the two teeth appears as a cleft. (Thailand, Malaysia (West Malaysia), Indonesia (Java, Lombok)) . . . . . Strumigenys sydorata


 * Mandible in profile with preapical tooth about the same shape and size as the apicodorsal tooth; dorsal margin of mandible not depressed distal of preapical tooth, space between the two teeth appears as a short transverse margin. (Malaysia (Sarawak, Sabah), Indonesia (Kalimantan, Thnimbar), Philippines (Palawan, Luzon)) . . . . . Strumigenys arrogantia

30
return to couplet #20
 * Hairs on first gastral tergite flagellate, elongate and fine, slender and acute apically. Intercalary denticles absent between apicomedian and apicoventral spiniform teeth although a minute denticle may arise from about the dorsal midlength of the apicoventral tooth . . . . . 31


 * Hairs on first gastral tergite stiff, either simple, remiform or spatulate, straight to shallowly curved and blunt apically. One or two intercalary denticles present between apicomedian and apicoventral spiniform teeth or arising from near base of apicoventral tooth on its dorsal surface . . . . . 33

31
return to couplet #30
 * Head extremely broad, almost or quite as broad as long, CI ca 100. With head in full-face view the apical series of mandibular teeth extremely oblique, so that the apicoventral tooth arises preapically from the ventral surface of the mandible. Hairs on postpetiole flagellate, the same as those on first gastral tergite . . . . . 32


 * Head elongate, obviously longer than broad, CI ca 75. With head in full-face view the apical series of mandibular teeth nearly vertical, the apicoventral tooth does not arise preapically from the ventral surface of the mandible. Hairs on postpetiole stiff and remiform, contrasting strongly with the long flagellate hairs on first gastral tergite. (Malaysia (Sarawak, Sabah)) . . . . . Strumigenys trixodens

32
return to couplet #31
 * Mandibles shorter and stouter, MI 45-51. Length of apicodorsal tooth of mandible (measured from apex to junction with inner margin of mandible) 2.00-2.25 times the maximum mandibular width. Scape slightly shorter, SI 43-50. (Thailand, Malaysia (West Malaysia, Sarawak, Sabah), Brunei, Indonesia (Sumatra)) . . . . . Strumigenys rotogenys


 * Mandibles longer and narrower, MI 56-57. Length of apicodorsal tooth of mandible (measured from apex to junction with inner margin of mandible) 2.80-3.10 times the maximum mandibular width. Scape slightly longer, SI 51-54. (Malaysia (Sarawak)) . . . . . Strumigenys gyrogenys

33
return to couplet #30
 * Inner margin of mandible with a broad translucent cuticular lamella that extends from base of mandible to near base of apicodorsal tooth; at full closure inner margins very nearly touching throughout their length. (Thailand) . . . . . Strumigenys tritomea


 * Inner margin of mandible without a cuticular lamella; at full closure inner margins widely separated throughout their length . . . . . 34

34
return to couplet #33
 * Pleurae and side of propodeum mostly or entirely smooth. Dorsal (outer) surface of hind basitarsus with a number of projecting long straight hairs that are filiform to weakly remiform and about three times longer than the maximum width of the basitarsus. (Malaysia (West Malaysia, Sarawak), Philippines (Luzon), Indonesia (Sulawesi)) . . . . . Strumigenys chapmani


 * Pleurae and side of propodeum entirely finely reticulate-punctate. Dorsal (outer) surface of hind basitarsus with relatively short curved spatulate hairs that are somewhat elevated and only slightly longer than the maximum width of the basitarsus. (Malaysia (Sarawak)) . . . . . Strumigenys treptodens

35
return to couplet #19 enormous, at least equal to the maximum width of the first coxa . . . . . 36
 * With alitrunk in profile the diameter of the excavated area of the mesopleural gland


 * With alitrunk in profile the diameter of the excavated area of the mesopleural gland small to moderate, much less than the maximum width of the first coxa . . . . . 42

36
return to couplet #35
 * With petiole in profile, and also in dorsal view, the lateral spongiform lobe of the node extends forward to about the level of the spiracle on the peduncle . . . . . 37


 * With petiole in profile, and also in dorsal view, the lateral spongiform lobe is confined to the node and does not extend forward to the spiracle on the peduncle . . . . . 40

37
return to couplet #36
 * Mandible with a small but distinct preapical tooth. (Philippines (Luzon)) . . . . . Strumigenys mirifica


 * Mandible without trace of preapical teeth or denticles . . . . . 38

38
return to couplet #37
 * Head in profile with extremely long erect hairs arising from the highest point of the dorsum and also from the surface anterior to the highest point; these hairs as long as those that arise close to the occipital margin. With mandible in frontal view curve between bases of apicodorsal and apicoventral teeth wide and very broadly V-shaped. With alitrunk in profile glandular excavation in anterior margin of mesopleuron usually distinctly longer than remaining length of katepisternum. Head narrower, scape longer, CI 57-64, SI 103-128 . . . . . 39


 * Head in profile with hairs that arise in front of highest point of dorsum much shorter than those arising more posteriorly. With mandible in frontal view angle between bases of apicodorsal and apicoventral teeth V-shaped to narrowly V-shaped. With alitrunk in profile glandular excavation in anterior margin of mesopleuron usually slightly shorter than remaining length of katepisternum. Head broader, scape shorter, CI 66-74, SI 86-97. (Thailand, Malaysia (West Malaysia, Sarawak, Sabah), Indonesia (Sumatra, Java, Bali, Lombok, Sumba, Ambon, Sulawesi, Timor)) . . . . . Strumigenys doriae

39
return to couplet #38
 * In oblique dorsal view side of propodeum without dense standing pubescence that obscures the spiracle. Short grey pubescence on dorsal alitrunk relatively sparse on pronotum and propodeum, these areas without a furry appearance. (Malaysia (West Malaysia, Sarawak)) . . . . . Strumigenys magnifica


 * In oblique dorsal view side of propodeum with dense standing pubescence that obscures the spiracle. Short grey pubescence on dorsal alitrunk very dense on pronotum and propodeum, these areas with a furry appearance. (Malaysia (Sabah), Brunei) . . . . . Strumigenys gloriosa

40
return to couplet #36
 * Mandible with 2 minute preapical denticles. Surface of first gastral tergite with dense appressed grey pubescence between the bases of the erect flagellate hairs. In dorsal view pronotal humeri angulate. (Malaysia (Sabah)) . . . . . Strumigenys hekate


 * Mandible without trace of preapical denticles. Surface of first gastral tergite without pubescence between the bases of the erect flagellate hairs. In dorsal view pronotal humeri rounded . . . . . 41

41
return to couplet #40
 * With mandible in frontal view angle between bases of apicodorsal and apicoventral teeth very broadly V-shaped; apicoventral tooth about same length as apicodorsal. Head narrower, mandibles shorter and scapes longer, CI 57-60, MI 46-48, SI 112-118. (Malaysia (Sarawak)) . . . . . Strumigenys superba


 * With mandible in frontal view angle between bases of apicodorsdal and apicoventral teeth narrow and V-shaped; apicoventral tooth much shorter than apicodorsal. Head broader, mandibles longer and scapes shorter, CI 65, MI 53, SI 99. (Malaysia (Sarawak, Sabah)) . . . . . Strumigenys bryanti

42
return to couplet #35
 * Preapical dentition of each mandible of two articles; either with 2 preapical teeth or with one tooth and a denticle . . . . . 43


 * Preapical dentition of each mandible either absent or of a single article; when present with either a single tooth or a single denticle . . . . . 47

43
return to couplet #42
 * Proximal preapical tooth much shorter than distal preapical tooth, the former in the basal half of the mandible length. Mesonotum and first gastral tergite without standing hairs . . . . . 44


 * Proximal preapical tooth longer than distal preapical tooth, both in the apical third of the mandible length. Mesonotum and first gastral tergite with standing hairs . . . . . 45

44
return to couplet #43
 * With petiole in profile the node with a short steeply ascending anterior face that separates the peduncle from the dorsum. Cephalic dorsum feebly superficially shagreenate on posterior half, without ground-pilosity and without a pair of erect hairs at highest point of vertex. (Solomon Is) . . . . . Strumigenys decollata


 * With petiole in profile the node without a steeply ascending anterior face, the peduncle grading into the dorsum through a shallowly convex long even curve. Cephalic dorsum reticulate-rugulose on posterior half, with spatulate ground-pilosity and with a pair of erect hairs at highest point of vertex. (Papua New Guinea) . . . . . Strumigenys praecollata

45
return to couplet #43
 * Ventrolateral margin of the head deeply indented immediately in front of the eye, so deeply that the anterior portion of the eye is detached from the side of the head. Ventral surface of head with a transverse preocular impression that is posterior to and separate from the postbuccal groove. (Cosmopolitan tramp species) . . . . . Strumigenys rogeri


 * Ventrolateral margin of the head continuous to the anterior margin of the eye, without trace of an indentation of the margin immediately in front of the eye. Ventral surface of head without a transverse preocular impression that is posterior to and separate from the postbuccal groove . . . . . 46

46
return to couplet #45
 * With postpetiole in profile its ventral spongiform lobe smaller than the exposed cuticle of the swollen disc. Larger species, HL 0.60-0.64, HW 0.46-0.48. (Indonesia (Timor)) . . . . . Strumigenys integra


 * With postpetiole in profile its ventral spongiform lobe larger than the exposed cuticle of the disc. Smaller species, HL 0.49-0.55, HW 0.40-0.43. (Indonesia (Bali, Lombok) . . . . . Strumigenys yanintra

47
return to couplet #42
 * With head in full-face view mandible without preapical dentition, no trace of a projecting preapical tooth or denticle . . . . . 48


 * With head in full-face view mandible with preapical dentition, a projecting preapical tooth or denticle present . . . . . 54

48
return to couplet #47
 * Dorsal (outer) surface of middle and hind basi tarsus with two or more very long projecting suberect to erect hairs that are finely filiform or flagellate and very much longer than the maximum width of the segment from which they arise. First gastral tergite with fine soft filiform to flagellate hairs . . . . . 49


 * Dorsal (outer) surface of middle and hind basitarsus without long projecting suberect to erect hairs; any pilosity present is short, simple to spatulate and decumbent to appressed. First gastral tergite with stiff simple blunt hairs . . . . . 52

49
return to couplet #48
 * First gastral tergite with dense appressed greyish pubescence covering the sclerite between the bases of the erect long hairs. (Malaysia (Sarawak), Brunei) . . . . . Strumigenys cygarix


 * First gastral tergite with the surface bare between the bases of the erect long hairs, without any appressed pubescence . . . . . 50

50
return to couplet #49
 * Side of alitrunk evenly longitudinally sulcate everywhere. Coxa of front leg transversely sulcate. (Thailand) . . . . . Strumigenys caniophanes


 * Side of alitrunk without sulcate sculpture; side either finely granulate or punctate, or partly smooth. Coxa of front leg not sulcate . . . . . 51