Key to species of Leptogenys found in China based on the worker caste, based on Chen et al. (2024).

At the end of this key is a previous key prepared by Zhou et al. (2012) and modified by Xu (2000).

1

Masticatory margin of mandible with > 2 teeth and denticles in addition to the apical one => 2
Masticatory margin of mandible usually edentate, at most with 1 tooth in addition to the apical one => 8

2

return to couplet #1

Head quadrate or roughly trapezoidal in full-face view approx. as broad as long. Petiolar node longitudinally compressed and squamiform in lateral view, acute at summit, without distinct dorsal margin, the node above anterior and posterior articulations ≥ 2 × as broad as long in dorsal view => 3
Head rectangular in full-face view, distinctly longer than broad. Petiolar node longitudinally thickened or elongate, or roughly triangular, or cubical in lateral view, dorsal margin long or narrowly convex, always distinct, the node above anterior and posterior articulations ≤ 1.5 × as broad as long in dorsal view => 4

3

return to couplet #2

Medial side of eyes on dorsum of head longitudinally striate, anteromedian clypeal margin broadly angulate. Antennal segments IV–VI approx. as broad as long. Subpetiolar process broad and triangular. Body color reddish brown (Myanmar, India, China, Thailand) => Leptogenys birmana
Medial side of eyes on dorsum of head smooth and shiny, anteromedian clypeal margin bidentate. Antennal segments IV–VI longer than broad. Subpetiolar process narrow and cuneiform. Body color brownish black (India, Sri Lanka, Vietnam, China) => Leptogenys processionalis

4

return to couplet #4

Petiolar node erectly triangular in lateral view, dorsal and anterior margins form a single arch, the two margins not separated by a distinct blunt angle (Vietnam, China) => Leptogenys davydovi
Petiolar node subquadrate in lateral view, dorsal and anterior margins not forming a single arch, the 2 margins separated by a distinct blunt angle => 5

5

return to couplet #4

Petiolar node thickly trapezoidal in lateral view, dorsal margin as long as or longer than anterior margin. Body color brownish yellow (Myanmar, China) => Leptogenys crassicornis
Petiolar node thinly trapezoidal in lateral view, dorsal margin distinctly shorter than anterior margin. Body color reddish brown to black => 6

6

return to couplet #5

Mandible < 5 teeth, dorsum of the propodeum appears nearly straight and aligns with the promesonotum in the same horizontal plane => Leptogenys zhoui
Mandible ≥ 5 teeth, the dorsum of the promesonotum is higher than the propodeum => 7

7

return to couplet #6

Body size is relatively large (TL 6.4 mm). Subpetiolar process semicircular, rounded at apex. Body color reddish brown (China: Guangxi) => Leptogenys strena
Body size is relatively small (TL 5.2 mm). Subpetiolar process triangular, angled at apex. Body color black (India, Myanmar; China: Yunnan) => Leptogenys lucidula

8

return to couplet #1

Head dorsum striate throughout => 9
Head dorsum punctate throughout or mostly smooth and shiny, at most punctate or rugose anterior to eyes => 11

9

return to couplet #8

Head slightly wider than long in full-face view. Petiolar node posterodorsal corner prominent with elongated triangular denticle => Leptogenys hainanensis
Head longer than wide in full-face view. Petiolar node posterodorsal corner broadly rounded without triangular denticle => 10

10

return to couplet #9

Clypeus with distinct longitudinal central carina. Sides of pronotum smooth, finely rugulose or finely reticulate; sides of mesothorax, metathorax and propodeum irregularly rugose (India, Sri Lanka, Myanmar, China, Thailand, Philippines, Malaysia, Singapore, Indonesia, New Guinea, Solomon Islands => Leptogenys diminuta
Clypeus without longitudinal central carina. Mesosoma and petiolar node regularly longitudinally striate (India, Myanmar, Thailand, Vietnam, China, Malaysia, Indonesia, New Guinea) => Leptogenys kitteli

11

return to couplet #8

Head dorsum punctate throughout => 12
Head dorsum mostly smooth and shiny, at most punctate or rugose anterior to eyes => 20

12

return to couplet #11

First gastral segment mostly punctate => 13
First gastral segment smooth and shiny => 16

=13

return to couplet #13

Head roughly rectangular in full-face view, not widening anteriorly, posterior margin roundly convex. Anterior apex of clypeus strongly convex (China) => Leptogenys hezhouensis
Head roughly trapezoidal in full-face view, distinctly widening anteriorly, posterior margin nearly straight. Anterior apex of clypeus truncate or nearly truncate => 14

14

return to couplet #13

Antennae relatively shorter, only one fourth of length of scape surpassing posterior head corner, segments 3 and 4 approx. equal. Anterior margin of petiolar node in lateral view straight and vertical (China) => Leptogenys yandii
Antennae relatively longer, 1/3 to 1/2 of length of scape surpassing posterior head corner, segment 3 distinctly longer than segment 4. Anterior margin of petiolar node weakly convex and slope, anterodorsal corner broadly rounded => 15

15

return to couplet #14

Eyes larger and occupying 1/3 of head side. Antennae shorter, 1/3 of scape length surpassing posterior head corner. Head dorsum finely densely punctate. Dorsa of mesosoma, petiole, and first gastral segment sparsely punctate with interspaces relatively shiny; sides of mesosoma and petiolar node longitudinally rugose, posterior 2/3 of side of first gastral segment smooth and shiny, second gastral segment smooth and shiny. Total length 5–6 mm (India, Philippines, China) => Leptogenys punctiventris
Eyes smaller and occupying 1/4 of head side. Antennae longer, near 1/2 of scape length surpassing posterior head corner. Head, mesosoma, petiole, and first gastral segment densely punctate with interspaces coarsely reticulate rugose and dull, second gastral segment sparsely punctate. Total length 9–10 mm (Myanmar, India, China) => Leptogenys binghamii

16

return to couplet #12

Clypeus truncate at apex (China) => Leptogenys huapingensis
Clypeus convex at apex, not truncate => 17

17

return to couplet #16

Dorsal faces of head, mesosoma and petiolar node densely punctate and opaque => 18
Dorsal face of head loosely punctate with interspaces relatively shiny, dorsal faces of mesosoma and petiolar node smooth and shiny => 19

18

return to couplet #17

Inner margin of mandible roundly convex, basal corner bluntly angled. Pronotum densely punctate with sides longitudinally striate. Anterodorsal corner of petiolar node broadly rounded in lateral view. Body color black. Robust species with total length 7.1–7.8 mm (China) => Leptogenys zhuangzii
Inner margin of mandible nearly straight, basal corner rounded without clear angle. Pronotum finely rugulose with sides smooth and shiny. Anterodorsal corner of petiolar node narrowly rounded in lateral view. Body color blackish brown. Slender species with total length 4.5–5.0 mm (China) => Leptogenys laozii

19

return to couplet #17

Petiolar node higher than long in lateral view, with anterodorsal corner narrowly rounded. Mesopleuron and metapleuron mostly smooth and shiny. Body color black to blackish brown. Total length 4.5–5.2 mm (China) => Leptogenys mengzii
Petiolar node as high as long in lateral view, with anterodorsal corner broadly rounded. Mesopleuron and metapleuron mostly densely rugose and opaque. Body color reddish brown. Total length 5.6–6.4 mm (China) => Leptogenys rufida

20

return to couplet #11

Petiolar node strongly elongate in lateral view, ~ 1.5 × as long as high (China) => Leptogenys pangui
Petiolar node moderately to weakly elongate in lateral view, < 1.2 × as long as high => 21

21

return to couplet #20

Petiolar node moderately elongate, as long as high or distinctly longer than high in lateral view => 22
Petiolar node weakly elongate, distinctly higher than long in lateral view, 1.3–1.4 × as high as long => 25

22

return to couplet #21

Clypeus truncated at apex. Lager species with total length 8–11 mm => 23
Clypeus convex at apex. Smaller species with total length 4.5–7 mm => 24

23

return to couplet #22

Clypeus anterior clypeal lobes divided into 2 teeth. dorsal faces between eyes and antennal sockets smooth and shiny, without longitudinal rugae. Petiolar node relatively broader in dorsal view, 1.3 × as long as broad, (India, Sri Lanka, Philippines, China) => Leptogenys chinensis
Clypeus anterior clypeal lobes round, dorsal faces between eyes and antennal sockets longitudinal rugose and opaque. Petiolar node relatively narrower in dorsal view, 2 × as long as broad (Indonesia, Vietnam, Thailand, China) => Leptogenys kraepelini

24

return to couplet #22

Petiolar node distinctly longer than high in lateral view.(PL 0.63, PH 0.51 CASENT0281935) Sides of mesothorax, metathorax, and propodeum mostly smooth and shiny. Body color black. Relatively larger species with total length 5.9–6.3 mm (Vietnam, Myanmar, India, Sri Lanka, Bangladesh, Thailand, Philippines, Singapore, Indonesia, China) => Leptogenys peuqueti
Petiolar node as high as long in lateral view. Sides of mesothorax, metathorax, and propodeum mostly irregularly rugose and opaque. Body color black, gaster blackish brown. Relatively smaller species with total length 4.5 mm (Japan, China) => Leptogenys confucii

25

return to couplet #21

In full-face view, greatest width of eye roughly equal to or less than the greatest width of antennal scape. Petiolar node relatively longer in lateral view, 1.3 × as high as long, dorsal margin distinctly longer than anterior margin (China) => Leptogenys laeviterga
In full-face view, greatest width of eye markedly greater than the maximum width of antennal scape. Petiolar node relatively higher in lateral view, ~ 1.4 × as high as long, dorsal margin as long as anterior margin (China) => Leptogenys sunzii

References

Chen, C., Chen, Z., Xu, Z., Fu, Q., Fu, L. 2024. Two new ant species of the genus Leptogenys (Hymenoptera, Formicidae) from Hainan, China, with a key to the known Chinese species. ZooKeys, 1195, 199–217 (doi:10.3897/zookeys.1195.115889).

Previous Version

This worker key is based on: Zhou, S., Chen, Y., Chen, Z., Zhou, P., Ban, D. & Huang, M. 2012. Two new species of the genus Leptogenys from Guangxi, China. Sociobiology 59: 885-892 and Xu, Z.H. 2000A. Five new species and one new record of the ant genus Leptogenys Roger (Hymenoptera: Formicidae) from Yunnan Province, China. Entomologia Sinica. 7:117-126.

1

Masticatory margin of mandible with 3 or more than 3 teeth. Head nearly square . . . . . 2

Masticatory margin of mandible without or with only 1 tooth. Head elongate, distinctly longer than broad . . . . . 5

Xu 2000. Figures 1-28.

2

return to couplet #1

Inner margin of mandible without tooth . . . . . 3
Inner margin of mandible with tooth . . . . . 4

3

return to couplet #2

Masticatory margin of mandible with 3 teeth, inner margin without tooth. In dorsal view petiolar node trapezoid (Figs. 1-4) (China: Yunnan Province; Myanmar) . . . . . Leptogenys crassicornis

Leptogenys crassicornis

Masticatory margin of mandible with more than 5 teeth, in dorsal view petiolar node subsemicirular (China: Hunan, Guangxi) . . . . . Leptogenys strena

4

return to couplet #2

Inner margin of mandible with 1 tooth. In dorsal view petiolar node semicircular. Head and alitrunk black (Figs. 5-8) (China: Yunnan Province) . . . . . Leptogenys huangdii

Inner margin of mandible with 3 or more than 3 teeth. In dorsal view petiolar node crescent-shaped. Head and alitrunk dark reddish brown (Figs. 9-12) (China: Yunnan Province; Myanmar; India) . . . . . Leptogenys birmana

Leptogenys birmana

5

return to couplet #1

Head smooth and shining . . . . . 6

Head longitudinally striate or densely punctate . . . . . 11

6

return to couplet #5

Scape of antenna surpassing occipital corner by half of its length (Figs. 13-16) (China: Yunnan Province) . . . . . Leptogenys pangui

Scape of antenna surpassing occipital corner by less than half of its length . . . . . 7

7

return to couplet #6

Head, alitrunk and gaster without metallic luster . . . . . 8

Head, alitrunk and gaster with blue or purple metallic luster . . . . . 9

8

return to couplet #7

Anterior margin of clypeus not truncate, without denticle in the middle (China: Zhejiang, Hunan; Vietnam: Myanmar: Sri Lanka) . . . . . Leptogenys peuqueti

Leptogenys peuqueti

Anterior margin of clypeus truncate, with a pair of denticles in the middle (China: Guangxi) . . . . . Leptogenys laeviterga

9

return to couplet #7

Anterior margin of clypeus truncate (Figs. 17-20) (China: Yunnan Guangxi, Taiwan; India; Sri Lanka; Philippines) . . . . . Leptogenys chinensis

Leptogenys chinensis

Anterior margin of clypeus extruding . . . . . 10

10

return to couplet #9

Body black. Subpetiolar process rounded at apex (Figs. 21-24) (China: Yunnan, HunanGuangxi, Hong Kong, Macao; Myanmar; India; Bangladesh) . . . . . Leptogenys minchinii

Leptogenys minchinii

Body dark yellowish brown. Subpetiolar process triangular, angled at apex (Figs. 25-28) (China: Taiwan Province; Japan) . . . . . Leptogenys confucii

11

return to couplet #5

Head longitudinally striate . . . . . 12

Head densely punctate . . . . . 13

Xu 2000. Figures 29-52.

12

return to couplet #11

Clypeus with longitudinal central carina (Figs. 29-32) (China: Yunnan, Guangdong, Guangxi, Taiwan; Myanmar; India; Sikkim; Sri Lanka; Malaysia) . . . . . Leptogenys diminuta

Leptogenys diminuta

Clypeus without longitudinal central carina (Figs. 33-36) (China: Yunnan, Guizhou, Hunan, Guangxi, Fujian, Taiwan, Hong Kong; Myanmar; Sikkim; India) . . . . . Leptogenys kitteli

Leptogenys kitteli

13

return to couplet #11

Masticatory margin of mandible as long as inner margin. Masticatory margin with 1 small tooth in the middle (Figs. 37-40) (China: Yunnan) . . . . . Leptogenys zhuangzii

Masticatory margin of mandible shorter than inner margin. Masticatory margin without tooth in the middle . . . . . 14

14

return to couplet #13

Anterior margin of clypeus truncate . . . . . 15
Anterior margin of clypeus extruded . . . . . 17

15

return to couplet #14

Anterior margin of clypeus without denticle in the middle (China: Guangxi) . . . . . Leptogenys huapingensis

Anterior margin of clypeus with a pair of denticles in the middle . . . . . 16

16

return to couplet #15

Head, alitrunk, and petiole densely and coarsely punctate (China: Guangxi) . . . . . Leptogenys binghamii

Dorsum of head in front of the eyes finely punctuate, alitrunk and petiole smooth and shining (China: Guangxi) . . . . . Leptogenys rufida

17

return to couplet #14

Masticatory and inner margins of mandible separated by a blunt angle (China: Yunnan Province) . . . . . Leptogenys mengzii

Masticatory margin of mandible rounded into inner margin . . . . . 18

18

return to couplet #17

Dorsum of propodeum a little longer than declivity, 2nd segment of flagellum of antenna longer than the 3rd segment (China: Guangxi) . . . . . Leptogenys hezhouensis

Dorsum of propodeum about 3 times as long as declivity, 2nd and 3rd segments of flagellum of antenna about equal (China: Yunnan) . . . . . Leptogenys laozii