Key to Strumigenys of East Asia (as Pyramica)

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 Pyramica

Bolton noted: Strumigenys formosa of Taiwan (p. 452), known only from queens, is omitted from the key. Its workers would be expected to key out around couplets 26-27.

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 a Key to Strumigenys of East Asia.

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 * Strumigenys

1

 * Antenna with 4 segments; first funicular segment not separated from the 2-segmented apical club. (India, Nepal, Thailand, Malaysia (West Malaysia), Singapore) . . . . . Strumigenys nepalensis


 * Antenna with 5 or 6 segments; first funicular segment separated from the 2-segmented apical club by one or two small segments . . . . . 2

2
return to couplet #1
 * Antenna with 5 segments; first funicular segment separated from the 2-segmented apical club by a single small segment. (Malaysia (West Malaysia)) . . . . . Strumigenys gyges


 * Antenna with 6 segments; first funicular segment separated from the 2-segmented club by two small segments . . . . . 3

3
return to couplet #2
 * With head in full-face view the leading edge of the scape with a row of conspicuous projecting curved hairs, of which one or more, distal to the subbasal bend, distinctly curves toward the base of the scape. These hairs may be spatulate, remiform, spoon-shaped or broadly clavate apically; basal stem of each hair (which may be short) erect or sub erect with respect to the long axis of the scape . . . . . 4


 * With head in full-face view the leading edge of the scape lacking projecting hairs that curve toward the base of the scape. Scape edge may have elongate simple straight projecting hairs present, or entirely apically directed short hairs that may be simple, narrowly to broadly spatulate, or spoon-shaped; in some species the leading edge may be hairless . . . . . 35

4
return to couplet #3
 * With head in full-face view the dorsolateral margin with a distinctly isolated, very conspicuous, laterally projecting apicoscrobal hair; apicoscrobal hair conspicuously differentiated from other pilosity on the margin, may be simple, clavate or flagellate . . . . . 5


 * With head in full-face view the dorsolateral margin without a distinctly isolated apicoscrobal hair that is conspicuously differentiated from other pilosity on the margin; either hair absent or duplicated by others on the margin . . . . . 23

5
return to couplet #4
 * Pronotal humeral hair absent. Dorsum of pronotum densely clothed with scale-like or stud-like broad hairs. Ventral margin of petiole peduncle without a longitudinal spongiform strip from base to level of node. Base of first gastral sternite without spongiform tissue. Standing stout hairs on first gastral tergite restricted to a single transverse row of four extremely close to the base. (Malaysia (Sarawak)) . . . . . Strumigenys clotho


 * Pronotal humeral hair present, may be simple, clavate, remiform or flagellate. Dorsum of pronotum lacking scale-like or stud-like broad hairs. Ventral margin of petiole peduncle with a continuous longitudinal spongiform strip from base to level of node, even if only narrowly so. Base of first gastral sternite with spongiform tissue. Standing hairs on first gastral tergite not restricted to a single transverse row close to the base . . . . . 6

6
return to couplet #5
 * Pronotal humeral hair long and flagellate; either freely projecting, or with its apical portion looped . . . . . 7


 * Pronotal humeral hair not flagellate; either simple and shallowly curved, or narrowly clavate, or remiform . . . . . 10

7
return to couplet #6
 * Cephalic dorsum with a transverse row of 4 standing hairs immediately in front of the occipital margin, but without a similar pair in front of the highest point of the vertex. Apicoscrobal hair not flagellate . . . . . 8


 * Cephalic dorsum with a transverse row of 4 standing hairs immediately in front of the occipital margin, and with a pair of similar standing hairs just in front of the highest point of the vertex. Apicoscrobal hair flagellate . . . . . 9

8
return to couplet #7
 * Eye minute, with only 1 or 2 very small ommatidia. Mesopleuron and metapleuron, and side of propodeum, smooth and shining. (Malaysia (West Malaysia)) . . . . . Strumigenys vescops


 * Eye larger, distinctly with more than 2 ommatidia. Mesopleuron smooth but metapleuron and side of propodeum reticulate-punctate. (Marquesas Is) . . . . . Strumigenys mumfordi

9
return to couplet #7
 * Mesonotum in profile with a single pair of erect long stout hairs, situated anteriorly on the sclerite. (Malaysia (West Malaysia, Sabah), Philippines (Luzon), Indonesia (Bali, Sumatra, Sulawesi, Kai Besar, Aru), Papua New Guinea, Solomon Is, Palau Is, also present in Australia) . . . . . Strumigenys karawajewi


 * Mesonotum in profile with two pairs of erect long stout hairs, the posterior pair usually distinctly the longer. (Bhutan, China, Burma, Thailand, Malaysia (West Malaysia, Sarawak, Sabah), Philippines (Luzon), Indonesia (Kalimantan, Bali, Java, Sumatra)) . . . . . Strumigenys dohertyi

10
return to couplet #6
 * Apical (masticatory) margin of mandible finely serrate, with distinctly more than 20 small to minute denticles crowded along the margin; basal 5-7 teeth not large and not the only ones clearly visible when the mandibles are fully closed . . . . . 11


 * Apical (masticatory) margin of mandible dentate, with 1 2 teeth and denticles in total on the margin; basal 5-7 teeth relatively large and the only ones clearly visible when the mandibles are fully closed . . . . . 12

11
return to couplet #10
 * First gastral tergite behind level of basigastral costulae (when clean) finely and densely coriaceous; the same sculpture also present on apical half of first gastral sternite. Disc of postpetiole not uniformly sharply reticulate-punctate. (Indonesia (Sulawesi)) . . . . . Strumigenys serraformis


 * First gastral tergite behind level of basigastral costulae (when clean), and first gastral sternite, glassy smooth and highly polished, without coriaceous sculpture. Disc of postpetiole very uniformly sharply reticulate-punctate. (Philippines (Luzon)) . . . . . Strumigenys serradens

12
return to couplet #10
 * With head in full-face view the outer margins of the mandibles shallowly concave behind the apical third; the mandibles relatively long, MI 35-36. Anterior face of petiole node in profile more or less continuing the line of the peduncle in a sinuous curve, the two not separated by a marked angle. (Indonesia (Sulawesi)) . . . . . Strumigenys rhea


 * With head in full-face view the outer margins of the mandibles evenly shallowly convex; the mandibles relatively short, MI 21-29. Anterior face of petiole node in profile separated from the line of the peduncle by a marked obtuse angle . . . . . 13

13
return to couplet #12
 * In dorsal view the disc of the postpetiole smooth and shining (when clean), without reticulate-punctate or punctate-rugulose sculpture, without trace of longitudinal costulae or at most with vestigial sculpture. If sculpture vestiges present then HW < 0.50 . . . . . 14


 * In dorsal view the disc of the postpetiole sculptured, either reticulate-punctate, punctate-rugulose, or finely densely and usually sharply longitudinally costulate across most or all of its surface. If sculpture partially effaced then HW 0.50 or greater . . . . . 20

14
return to couplet #13
 * Pronotal humeral hair elongate and gradually tapering to an acute apex. With waist segments in dorsal view the petiole node shining, similar to the disc of the postpetiole. SI ca 67, CI ca 75 . (Tahiti) . . . . . Strumigenys insula


 * Pronotal humeral hair stout, truncated-remiform or weakly clavate apically. With waist segments in dorsal view the petiole node reticulate-punctate, contrasting strongly with the smooth disc of the postpetiole. SI 50-60, CI 78-94 . . . . . 15

15
return to couplet #14
 * Side of pronotum obliquely costulate. Metapleuron and side of propodeum longitudinally costulate. Ventral spongiform strip of petiole reduced to a carina-like vestige beneath the peduncle. (Papua New Guinea) . . . . . Strumigenys tethys


 * Side of pronotum partially to entirely reticulate-punctate. Metapleuron and side of propodeum mostly smooth to entirely reticulate-punctate, never costulate. Ventral spongiform strip of petiole distinct beneath the peduncle . . . . . 16

16
return to couplet #15
 * Alitrunk in profile with dorsal outline evenly sloping downwards posteriorly, usually at an angle of about 45 0, from anterior mesonotum to propodeal tooth; without an impressed metanotal groove and without a change of slope between mesonotum and propodeum. Head broad, CI > 90. Alitrunk short and stocky, the pronotum broad; AL < 1.50 X maximum alitrunk height, AL about 1.70 X pw. (Papua New Guinea) . . . . . Strumigenys phasma


 * Alitrunk in profile with dorsal outline not evenly sloping downwards from anterior mesonotutn to propodeal tooth; either mesonotum and propodeum form separate convexities, or metanotal groove distinctly impressed, or with a marked change of slope between mesonotum and propodeum. Head narrower, CI 79-89. Alitrunk longer and narrower; AL > 1.50 X maximum alitrunk height, AL 1.80-2.00 X PW . . . . . 17

17
return to couplet #16
 * Mesonotal dorsum with a single pair of stout standing hairs . . . . . 18


 * Mesonotal dorsum with two pairs of stout standing hairs . . . . . 19

18
return to couplet #17
 * Disc of petiole node in dorsal view much broader than long, transversely rectangular. Postpetiole massively developed in dorsal view, its disc conspicuously twice broader than long and twice as broad as the petiole node. Dark brown to black species with MI 26-27. (Fiji Is) . . . . . Strumigenys trauma


 * Disc of petiole node in dorsal view at most only fractionally broader than long, not transversely rectangular. Postpetiole relatively small in dorsal view, its disc distinctly less than twice broader than long, less than twice as broad as the petiole node. Light reddish-brown species with MI 21-22. (Samoa) . . . . . Strumigenys epipola

19
return to couplet #17
 * In dorsal view sides of petiole and postpetiole not entirely margined with projecting spongiform tissue. Ventral spongiform lobe of postpetiole in profile smaller than the exposed area of the postpetiole disc. With alitrunk in profile the propodeal dorsal outline markedly convex behind the metanotal groove. Yellow to light yellowish brown species with MI 25-29. (Indonesia (Sulawesi), Papua New Guinea) . . . . . Strumigenys themis


 * In dorsal view sides of both petiole and postpetiole thickly margined with projecting spongiform tissue. Ventral spongiform lobe of postpetiole in profile distinctly larger than the exposed area of the postpetiole disc. With alitrunk in profile the propodeal dorsal outline approximately flat and sloping posteriorly behind the metanotal groove. Darker reddish brown species with MI 2 1 . (Indonesia (Sumatra)) . . . . . Strumigenys charybdis

20
return to couplet #13
 * Leading edge of scape in dorsal view with subbasal bend developed into a projecting triangular flattened tooth before its narrow basal section (longest hair on margin arises from apex of this tooth). Very large species with head very broad, HW > 0.90, CI 97-101. (Papua New Guinea) . . . . . Strumigenys dentiscapa


 * Leading edge of scape in dorsal view with subbasal bend broadly shallowly and evenly convex before its narrow basal section. Markedly smaller species with narrower heads, HW 0.50-0.62, CI 80-89 . . . . . 21

21
return to couplet #20
 * Sides of alitrunk entirely sharply reticulate-punctate, without smooth unsculptured areas. Dorsum of mesonotum with 3 (or rarely 4) pairs of stout standing hairs. (Malaysia (Sabah)) . . . . . Strumigenys theia


 * Sides of alitrunk not entirely reticulate-punctate, with smooth un sculptured areas on mesopleuron, metapleuron, or propodeum. Dorsum of mesonotum with 2 pairs of standing hairs . . . . . 22

22
return to couplet #21
 * With petiole in profile the dorsal length of the node, discounting the posterior collar, greater than the height of the anterior face of the node; petiole node in dorsal view usually longer than broad. With postpetiole in profile the ventral spongiform lobe at least equal in area to the exposed portion of the disc. (Malaysia (West Malaysia), Philippines (Luzon, Negros) . . . . . Strumigenys pedunculata


 * With petiole in profile the dorsal length of the node, discounting the posterior collar, subequal to the height of the anterior face of the node; petiole node in dorsal view broader than long. With postpetiole in profile the ventral spongiform lobe much smaller in area than the exposed portion of the disc. (Indonesia (Sulawesi, Seram), Papua New Guinea) . . . . . Strumigenys capitata

23
return to couplet #4
 * Mandibles elongate and narrow, linear; in full-face view and at full closure only their extreme apices engage. Leading edge of scape with a large, strongly prominent subbasal lobe . . . . . 24


 * Mandibles sub triangular to triangular, not linear; in full-face view and at full closure they engage for half or more of their exposed length. Leading edge of scape with a gradual subbasal curve or subbasal angle, without a large, strongly prominent subbasal lobe . . . . . 28

24
return to couplet #23
 * Mandible without preapical teeth. Pronotal dorsum covered with numerous large flat orbicular hairs. Cephalic dorsum without a transverse blunt ridge or crest across highest point of vertex. Dorsum of mandible not abruptly depressed near base where it passes beneath the anterior clypeal margin . . . . . 25


 * Mandible with 2 or more preapical teeth. Pronotal dorsum not covered with large orbicular hairs. Cephalic dorsum with a transverse blunt ridge or crest across highest point of vertex. Dorsum of mandible abruptly depressed near base where it passes beneath the anterior clypeal margin . . . . . 26

25
return to couplet #24
 * Dorsal surface of mandible without longitudinal rows of anteriorly directed spoon-shaped or scale-like hairs. The two pairs of hairs closest to the midline on the anterior clypeal margin short, narrowly spoon-shaped and curved or inclined toward the midline. Orbicular hairs on clypeus all of approximately the same size. (Japan, Taiwan) . . . . . Strumigenys hirashimai


 * Dorsal surface of mandible with two longitudinal rows of anteriorly directed spoon-shaped or scale-like hairs. The two pair of hairs closest to the midline on the anterior clypeal margin long and strap-like, directed anteriorly and curved slightly away from the midline. Orbicular hairs on clypeus much smaller centrally than near lateral and posterior margins. (China) . . . . . Strumigenys lachesis

26
return to couplet #24
 * Eyes absent. Cephalic dorsum without small orbicular hairs. (Nepal) . . . . . Strumigenys hemisobek


 * Eyes present but minute, of only 1 or 2 ommatidia. Cephalic dorsum with small orbicular hairs, at least immediately behind the clypeus . . . . . 27

27
return to couplet #26
 * Small orbicular hairs on head restricted to 2 transverse rows immediately behind the clypeus. Apicodorsal tooth of mandible short, at full closure not crossing over beyond the outer margin of the opposing mandible. Pronotal dorsum with longitudinal costulate sculpture. (Malaysia (Sarawak), Indonesia (Sulawesi)) . . . . . Strumigenys dyschima


 * Small orbicular hairs on head present from immediately behind clypeus to the arched transverse crest across the highest point of the vertex. Apicodorsal tooth of mandible very long and spiniform, at full closure crossing over beyond the outer margin of the opposing mandible. Pronotal dorsum reticulate-punctate. (Malaysia (West Malaysia)) . . . . . Strumigenys murphyi

28
return to couplet #23
 * Pronotal humeral hair absent . . . . . 29


 * Pronotal humeral hair present; may be simple, flagellate, remiform or subclavate . . . . . 31

29
return to couplet #28
 * Fully closed mandibles in full-face view with crowded series of small teeth on the distal halves of the masticatory margins, but the proximal halves are edentate and concave, and enclose a broad subovate gap in front of the anterior clypeal margin. (Taiwan) . . . . . Strumigenys takasago


 * Fully closed mandibles in full-face view with teeth extending from apex of masticatory margin to the point where the margin intersects the anterior clypeal margin . . . . . 30

30
return to couplet #29
 * Entire mesopleuron and metapleuron blanketed with dense reticulate-punctate sculpture, without smooth shining areas. Petiole ventrally with a vestigial cuticular strip, not spongiform. First gastral tergite with numerous short curved spatulate hairs on the basal half, such hairs absent from apical half of sclerite. (Malaysia (Sabah)) . . . . . Strumigenys disjuncta


 * Entire mesopleuron and metapleuron smooth and shining, not blanketed with reticulate-punctate sculpture. Petiole ventrally with a deep spongiform curtain. First gastral tergite with sparse minute appressed pubescence only. (Cosmopolitan tramp species) . . . . . Strumigenys membranifera

31
return to couplet #28
 * Cephalic dorsum in full-face view with very conspicuous broad spoon-shaped to suborbicular ground-pilosity . . . . . 32


 * Cephalic dorsum in full-face view with slender narrowly spatulate ground pilosity . . . . . 33

32
return to couplet #31
 * Cephalic dorsum with a transverse row of four stiff erect hairs near occipital margin, these hairs contrasting strongly with the ground-pilosity. Dorsal (outer) surface of hind basitarsus with 1-2 very long fine erect flagellate hairs. Leading edge of scape distal of the subbasal angle with 3 or more hairs that are curved toward the base of the scape. (Thailand, Malaysia (West Malaysia)) . . . . . Strumigenys atropos


 * Cephalic dorsum without stiff erect hairs near occipital margin that contrast with the ground-pilosity. Dorsal (outer) surface of hind basitarsus without flagellate hairs. Leading edge of scape distal of the subbasal angle with only a single hair that is curved toward the base of the scape. (Japan) . . . . . Strumigenys hiroshimensis

33
return to couplet #31
 * Pronotal humeral hair fine, flagellate. Longest pair of hairs on dorsum of mesonotum fine and simple . . . . . 34


 * Pronotal humeral hair stout, simple to weakly remiform. Longest pair of hairs on dorsum of mesonotum stout, remiform to subclavate. (Japan) . . . . . Strumigenys rostrataeformis

34
return to couplet #33
 * Anterior clypeal margin distinctly concave in full-face view. Lateral margins of occipital lobes in full-face view with all hairs short stout and curved, without longer finer sub flagellate hairs. (Korea, Japan) . . . . . Strumigenys incerta


 * Anterior clypeal margin transverse or even shallowly convex in full-face view. Lateral margins of occipital lobes in full-face view with a mixture of shorter curved hairs and longer finer subflagellate hairs. (China) . . . . . Strumigenys emeswangi

35
return to couplet #3
 * Spongiform tissue of body enormously developed. In profile the petiole node and postpetiole disc appear to consist entirely of spongiform tissue, which also blankets the propodeum, metapleuron and dorsal rim of the mesonotum. (Brunei, Malaysia (Sarawak)) . . . . . Strumigenys kempfi


 * Spongiform tissue much less abundant. In profile the petiole node and postpetiole disc are visible, spongiform tissue is represented by lateral lobes and anterior and posterior collars on each segment; propodeum, metapleuron and mesonotum free from spongiform tissue although the lamellae of the propodeal declivity may sometimes be spongiform . . . . . 36

36
return to couplet #35
 * Petiole node in profile long and low; either anterior face of node much shorter than the long dorsum, or the anterior face shallowly sloped and grading evenly into the peduncle so that the entire segment is subclavate. Petiole node in dorsal view long and narrow, sometimes with a posterior peduncle, always much longer than broad and generally at least equal in length to the disc of the postpetiole . . . . . 37


 * Petiole node in profile short and relatively high; either anterior face of node at least subequal in length to the dorsum, or the anterior face steeply sloped and meeting the peduncle through an obtuse but marked angle, or both. Petiole node in dorsal view short and broad, usually at least as broad as long and generally shorter than the disc of the postpetiole . . . . . 57

37
return to couplet #36
 * Mandibles elongate and narrow in full-face view; masticatory margins engage only in the apical third or less of their length at full closure; proximally with a large gap between the mandibles, and between them and the anterior clypeal margin; labral lobes visible through the gap; MI > 25. Fully closed mandibles edentate from base to about the midlength in full-face view . . . . . 38


 * Mandibles stoutly triangular in full-face view; masticatory margins engage throughout their length at full closure; proximally without a gap between the mandibles nor between them and the anterior clypeal margin; labral lobes not visible; MI < 25. Fully closed mandibles dentate from anterior clypeal margin to apex in full-face view . . . . . 39

38
return to couplet #37
 * Flagellate hairs present on dorsolateral margins of head, pronotal humeri, waist segments, first gastral tergite and dorsal (outer) surfaces of tibiae and basitarsi. Aligned rows of appressed spatulate hairs entirely absent. Anterior clypeal margin with a small median tooth. Eye minute, with only 3-4 ommatidia in total. Scape very long and slender, SI > 100. (Malaysia (West Malaysia)) . . . . . Strumigenys acubecca


 * Flagellate hairs entirely absent. Aligned rows of appressed spatulate hairs conspicuous on cephalic dorsum, scapes and mandibles. Anterior clypeal margin evenly convex. Eye relatively large, with 5 ommatidia in the longest row. Scape short and stout, SI < 70. (China) . . . . . Strumigenys wilsoni

39
return to couplet #37
 * Masticatory margin of mandible with a total dental count of 5; all are stoutly conical and slightly recurved teeth, without denticles. Anterior clypeal margin transverse or nearly so. Apices of labral lobes truncated . . . . . 40


 * Masticatory margin of mandible with a total dental count of 12-18; with a basal series of 7-9 teeth that may be elongate triangular, conical or spiniform; distal to this series with a number of smaller teeth and denticles. Anterior clypeal margin evenly convex. Apices of labral lobes may be triangular, conical or digitate, but never truncated . . . . . 42

40
return to couplet #39
 * Dorsal (outer) surfaces of middle and hind tibiae and basitarsi with numerous erect long simple hairs. Dorsal surfaces of middle and hind femora with suberect to erect elongate simple hairs. Leading edge of scape with a row of short suberect clavate hairs. Basigastral costulae extend for some distance onto sclerite proper, not restricted to limbus. (Indonesia (Aru, Kai Besar, Thnimbar), Papua New Guinea, also present in Australia) . . . . . Strumigenys semicompta


 * Dorsal (outer) surfaces of middle and hind tibiae and basitarsi with short decumbent to appressed hairs. Dorsal surfaces of middle and hind femora without elongate simple hairs. Leading edge of scape with a row of closely appressed minute hairs. Basigastral costulae extremely short, traversing limbus but barely extending onto sclerite proper . . . . . 41

41
return to couplet #40
 * Cephalic dorsum behind clypeus entirely sculptured, with longitudinal rugulae present. Dorsolateral margin of occipital lobe with 3 short stiff projecting hairs; dorsum of head with a few erect short hairs near occipital margin. Pronotal humeral hair present, stiff and projecting laterally. Dorsal alitrunk with short erect hairs present along dorsolateral margins. (Papua New Guinea) . . . . . Strumigenys carnassa


 * Cephalic dorsum behind clypeus mostly smooth, without longitudinal rugulae. Dorsolateral margin of occipital lobe without projecting hairs; dorsum of head without erect hairs. Pronotal humeral hair absent. Dorsal alitrunk without erect hairs anywhere. (Indonesia (Irian Jaya)) . . . . . Strumigenys pydrax

42
return to couplet #39
 * Dorsal (outer) surface of hind tibia without suberect to erect straight simple projecting hairs; any hairs present are decumbent to closely appressed . . . . . 43


 * Dorsal (outer) surface of hind tibia with suberect to erect straight simple projecting hairs . . . . . 50

43
return to couplet #42
 * Postpetiole enormously inflated, in dorsal view its disc 0.42 long and 0.59 wide at maximum (discounting spongiform tissue). Larger species, HL 1.22. Head in profile extremely dorsoventrally flattened, its depth at level of eye only slightly greater than maximum diameter of eye. Propodeal spiracle located at apex of a V-shaped depression in side of sclerite. (Malaysia (Sarawak)) . . . . . Strumigenys bubisnoda


 * Postpetiole small, in dorsal view its disc less than 0.25 long and less than 0.30 wide at maximum (discounting spongiform tissue). Smaller species, HL less than 0.90. Head in profile not dorsoventrally flattened, its depth at level of eye much greater than maximum diameter of eye. Propodeal spiracle not located at apex of a V-shaped depression in side of sclerite . . . . . 44

44
return to couplet #43
 * Dorsal alitrunk with standing hairs present at least on the mesonotum. With petiole in profile the lateral spongiform lobe does not extend forward to the level of the spiracle on the peduncle. Propodeum with a pair of spines or acute teeth, each subtended by a narrow carina or lamella. Basigastral costulae present, short . . . . . 45


 * Dorsal alitrunk entirely lacking standing hairs. With petiole in profile the lateral spongiform lobe is very broad and extends forward to the level of the spiracle on the peduncle. Propodeal spines or teeth absent, the entire height of the declivity occupied by a broad lamella. Basigastral costulae absent. (India) . . . . . Strumigenys assamensis

45
return to couplet #44
 * Propodeal lobes (at base of declivity) elongate, narrowly acutely triangular. Declivity above the propodeal lobe margined only by a vestigial carina that extends upward to the propodeal spine. Mesopleuron entirely reticulate-punctate . . . . . 46


 * Propodeal lobes (at base of declivity) short, low and rounded. Declivity above the propodeal lobe margined by a granular or weakly spongiform lamella that distinctly engages the base of the propodeal tooth or spine. Mesopleuron mostly or entirely smooth and shining . . . . . 48

46
return to couplet #45
 * With head in profile dorsal outline of clypeus forms a shallow even convexity with the highest point at about the midlength; clypeal outline slopes evenly and gently upward from the basal margin of the mandible to the highest point and posterior to this slopes evenly and gently downward to the posterior clypeal apex . . . . . 47


 * With head in profile dorsal outline of clypeus does not form a shallow even convexity with the highest point at about the midlength; clypeal outline rises almost vertically from the basal margin of the mandible and passes through a bluntly bulging angle (vertical portion accounts for about one-third of length of outline), posterior to this the outline almost flat to the posterior clypeal apex. (Malaysia (Sabah)) . . . . . Strumigenys megaera

47
return to couplet #46
 * With head in profile the dorsum with a single transverse row of 4-6 short standing hairs posteriorly, immediately in front of the occipital margin. In full-face view dorsolateral margin of occipital lobe without freely projecting stiff hairs. Head narrower and scape longer, CI 56-60, SI 81-86. (Thailand) . . . . . Strumigenys scolopax


 * With head in profile the dorsum with numerous standing hairs posteriorly, obviously more than a single row immediately in front of the occipital margin. In full-face view dorsolateral margin of occipital lobe with 4-5 freely projecting stiff hairs. Head broader and scape shorter, CI 65-70, SI 71-77. (Malaysia (West Malaysia), Indonesia (Java)) . . . . . Strumigenys rudinodis

48
return to couplet #45
 * Lateral spongiform lobe of petiole in profile merely a small flap at the posterolateral angle of the node. With head in full-face view sides of occipital lobes without freely projecting simple hairs. Dorsum of head from highest point of vertex to occipital margin without erect to suberect straight simple hairs. (Korea, Japan, Taiwan) . . . . . Strumigenys japonica


 * Lateral spongiform lobe of petiole in profile elongate, extending forward almost to the level of the anterior face of the node. With head in full-face view side of each occipital lobe with 4-5 freely projecting short hairs. Dorsum of head from highest point of vertex to occipital margin with distinct erect to suberect straight simple hairs . . . . . 49

49
return to couplet #48
 * Pronotal dorsum with numerous long erect simple hairs. (Taiwan) . . . . . Strumigenys formosimonticola


 * Pronotal dorsum without long erect simple hairs. (Japan, Taiwan) . . . . . Strumigenys benten

50
return to couplet #42
 * With the head in full-face view the upper scrobe margin with a continuous row of short anteriorly directed decumbent to appressed hairs only, without elongate simple hairs that freely project beyond the margins; one or two freely projecting simple hairs may occur on the lateral occipital lobes well behind the level of the eyes . . . . . 51


 * With the head in full-face view the upper scrobe margins with straight or curved elongate simple hairs that freely project laterally or dorsolaterally beyond the margins; similar or even longer hairs project from the occipital lobes . . . . . 52

51
return to couplet #50
 * Anterior half of clypeal dorsum with a high median longitudinal crest that is densely clothed with narrow scale-like hairs. Pronotal dorsum sparsely but coarsely longitudinally costulate, punctate sculpture absent. Mesopleuron rugulose. (Malaysia (Sabah)) . . . . . Strumigenys euryale


 * Anterior half of clypeal dorsum shallowly transversely convex, without a median longitudinal crest. Pronotal dorsum superficially punctate, costulate sculpture absent. Mesopleuron punctulate. (Thailand, China, Taiwan) . . . . . Strumigenys elegantula

52
return to couplet #50
 * Leading edge of antennal scape with a series of straight anteriorly projecting simple hairs . . . . . 53


 * Leading edge of antennal scape without a series of straight anteriorly projecting simple hairs . . . . . 54

53
return to couplet #52
 * Dorsum of petiole node transversely rugulose. Propodeal spines short-triangular, engaging a conspicuous lamella that runs down the declivity. In profile dorsal outline of petiole peduncle and node separated by a change of slope, not forming a single shallow convexity. (Japan, Taiwan) . . . . . Strumigenys leptothrix


 * Dorsum of petiole node unsculptured. Propodeal spines narrow and acutely spiniform, subtended only by a vestigial carina that runs down the declivity. In profile dorsal outline of the petiole peduncle and node forming a single shallow convexity. (Indonesia (Sulawesi)) . . . . . Strumigenys stheno

54
return to couplet #52
 * Propodeal lobes at base of declivity lamelliform and broadly rounded. With petiole in profile the lateral spongiform lobe large, extending the entire length of the side of the node. Disc of postpetiole glassy smooth . . . . . 55


 * Propodeal lobes at base of declivity triangular and acute. With petiole in profile the lateral spongiform lobe very small, restricted to the posteroventral angle of the side of the node. Disc of postpetiole sculptured with longitudinal costulate or rugulae, even if only feebly so . . . . . 56

55
return to couplet #54
 * Pronotal dorsum sharply marginate dorsolaterally. Hairs that project from dorsal (outer) surface of hind tibia much longer than the maximum tibial width. In profile hairs on cephalic dorsum abundant, long and fine, present from posterior clypeal margin to occipital margin. (Malaysia (West Malaysia, Sarawak, Sabah), Indonesia (Sumatra), Philippines (Palawan)) . . . . . Strumigenys jacobsoni


 * Pronotal dorsum rounding broadly and evenly into the sides, not marginate. Hairs that project from dorsal (outer) surface of hind tibia shorter than the maximum tibial width. In profile hairs on cephalic dorsum short and stubbly, only present from about highest point of the vertex to occipital margin. (Japan) . . . . . Strumigenys alecto

56
return to couplet #54
 * Propodeal lobes elongate and narrowly triangular, more than half the length of the propodeal spines. Elongate hairs on dorsum of head erect in profile, weakly curved or sinuate along their length but not strongly arched forward. Pronotal dorsum with spaces between the longitudinal costulae vestigially punctulate to smooth. (Malaysia (Sabah)) . . . . . Strumigenys medusa


 * Propodeal lobes short and broadly triangular, much less than half the length of the propodeal spines. Elongate hairs on dorsum of head strongly arched forward in profile, their apices directed anteriorly. Pronotal dorsum with spaces between the longitudinal costulae densely reticulate-punctate. (Papua New Guinea) . . . . . Strumigenys scylla

57
return to couplet #36
 * Dorsal (outer) surfaces of middle and hind tibiae and basitarsi with small simple to spatulate decumbent or appressed hairs, or with minute appressed pubescence only; lacking freely laterally projecting long hairs that are at a right-angle or near rightangle to the long axis of the segment . . . . . 58


 * Dorsal (outer) surfaces of middle and hind tibiae with one or more conspicuous freely laterally projecting long hairs that are at a right-angle or near right-angle to the long axis of the segment; these hairs may be straight, curved or flagellate; one or more similar hairs present on basitarsi . . . . . 82

58
return to couplet #57
 * With the head in full-face view and the mandibles fully closed the dorsal surface of each massively triangular mandible has, near its base, a very distinct sharp transverse rim that extends across the width of the mandible . . . . . 59


 * With the head in full-face view and the mandibles fully closed the dorsal surface of each mandible, near its base, is without a sharp transverse rim that extends across the width of the mandible; if dorsum of mandible slightly depressed basally then mandible is linear, not triangular . . . . . 67

59
return to couplet #58
 * Either pronotum, mesonotum, or both with a single pair of straight standing hairs . . . . . 60


 * Both pronotum and mesonotum entirely lacking standing hairs . . . . . 62

60
return to couplet #59
 * Vertex in full-face view with an arched transverse crest across its widest point; in profile the crest is at the highest point of the vertex, the surface immediately in front of it is almost vertical. (Malaysia (Sabah)) . . . . . Strumigenys acheron


 * Vertex in full-face view without a transverse crest across its widest point; in profile the surface immediately in front of the highest point is evenly convex and rounded to the highest point . . . . . 61

61
return to couplet #60
 * Dorsal surface of mandible depressed basally, the depressed area bounded by a carina that commences laterobasally, runs anteriorly close to the lateral margin, then arches across the dorsum to intersect the masticatory margin at the third or fourth tooth. Pronotum without standing hairs. (Malaysia (West Malaysia)) . . . . . Strumigenys tarbosyne


 * Dorsal surface of mandible shallowly transversely convex basally, without a depressed area bounded by an arched carina. Pronotum with a single pair of standing hairs close to the humeri. (Malaysia (Sarawak)) . . . . . Strumigenys aello

62
return to couplet #59
 * Dorsal surface of mandible depressed basally, the depressed area bounded by a carina or arched ridge that commences near the outer basal angle, runs anteriorly close to the lateral margin, then curves across the dorsum at about the midlength to intersect the masticatory margin at about the fifth or sixth tooth from the base . . . . . 63


 * Dorsal surface of mandible not depressed basally, without a sharp carina or arched ridge that curves across the dorsum at about the midlength, without a dorsolateral carina running down to the outer basal angle . . . . . 64

63
return to couplet #62
 * Cephalic dorsum behind clypeus mostly smooth and shining, not reticulate-punctate. Mandibles smooth and shining. Vertex behind highest point without erect stout hairs. Subbasal lobe of scape without an enlarged spoon-shaped curved hair at its apex. Arched carina at midlength of mandibular dorsum low and blunt laterally, not forming a sharply raised dorsolateral ridge. (Indonesia (Sumatra)) . . . . . Strumigenys atopogenys


 * Cephalic dorsum behind clypeus reticulate-punctate everywhere. Mandibles shagreenate and dull. Vertex behind highest point with a pair of erect stout hairs. Subbasal lobe of scape with an enlarged spoon-shaped curved hair at its apex. Arched carina at midlength of mandibular dorsum markedly elevated and acute laterally, forming a sharply raised dorsolateral ridge. (Indonesia (Sumatra)) . . . . . Strumigenys carinognatha

64
return to couplet #62
 * Subbasal angle of leading edge of scape prominent and forming a distinctly projecting lobe. Apex of this lobe bears an anteriorly directed specialised hair that is different in structure from other hairs on the leading edge and is not curved toward the apex of the scape. Closed mandibles with dorsal surfaces transverse, the masticatory margins not markedly elevated above the level of the outer margins . . . . . 65


 * Subbasal angle of leading edge of scape rounded, not forming a projecting lobe. All hairs on leading edge small, spoon-shaped and curved toward the apex of the scape. Closed mandibles with dorsal surfaces markedly sloped, the masticatory margins elevated and the dorsum on each side forming a flat slope down to the much lower outer margins . . . . . 66

65
return to couplet #64
 * With alitrunk in dorsal view sides of mesonotum converging dorsally so that the dorsum of the sclerite is a narrow longitudinal ridge. Entire width of pronotal dorsum depressed, the depressed area surrounded by an almost circular raised rim. Leading edge of scape with a broad flat squamiform hair that projects anteriorly from apex of subbasal angle. Propodeal dorsum and upper half of declivity smooth. (Malaysia (Sabah, Sarawak)) . . . . . Strumigenys ocypete


 * With alitrunk in dorsal view sides of mesonotum do not converge dorsally to form a narrow longitudinal ridge. Pronotal dorsum flat, without an almost circular raised rim. Leading edge of scape with a narrow remiform hair that projects anteriorly from apex of subbasal angle. Propodeal dorsum and upper half of declivity reticulate-punctate. (Nepal, India) . . . . . Strumigenys podarge

66
return to couplet #64
 * Small scale-like hairs confined to clypeus and area immediately behind it. Dorsolateral margins of pronotum straight in dorsal view, distinctly angular posteriorly before their junction with the mesonotum. Lamella on propodeal declivity with the projecting apex of an acute tooth dorsally. (Malaysia (West Malaysia), Singapore) . . . . . Strumigenys extemena


 * Small scale-like hairs present all over dorsum of head. Dorsolateral margins of pronotum arched-convex in dorsal view, evenly curved posteriorly before their junction with the mesonotum. Lamella on propodeal declivity rounded dorsally, without a projecting tooth. (Malaysia (Sabah)) . . . . . Strumigenys deinognatha

67
return to couplet #58
 * With the head in full-face view the entire dorsum clothed with ground-pilosity of very conspicuous pale spoon-shaped to orbicular hairs . . . . . 68


 * With the head in full-face view the dorsum either without hairs or with ground-pilosity of short hairs that are simple to narrowly spatulate and usually inconspicuous . . . . . 72

68
return to couplet #67
 * Ventral surface of petiole without a spongiform strip. Hairs on first gastral tergite appressed, entirely scale-like to spoon-shaped. Anterior clypeal margin evenly narrowly convex. Mandibles at full closure engage through the length of the masticatory margin. Side of alitrunk entirely densely reticulate-punctate. (Indonesia (Aru I.)) . . . . . Strumigenys agostii


 * Ventral surface of petiole with a spongiform strip. Hairs on first gastral tergite suberect to erect, spatulate to clavate apically. Anterior clypeal margin transverse. Mandibles at full closure engage only at or near their apices. Side of alitrunk partly or entirely smooth and shining . . . . . 69