Key to Myrmecina of Southeast Asia

This worker key is based on: Okido, H., Ogata, K., Hosoishsi, S. 2020. Taxonomic revision of the ant genus Myrmecina in Southeast Asia (Hymenoptera: Formicidae). Bulletin of the Kyushu University Museum. 7:1-108.

The key presented below treats 48 species. The following 5 species are not examined and omitted from the key: Myrmecina butteli from Sumatra, Myrmecina nesaea from Sebesi I., Myrmecina semipolita from Java, Myrmecina striata from Myanmar, Myrmecina undulata from Sumatra.

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• Myrmecina
• Southeast Asia

1

• Lateral portions of clypeus raised into a sharp ridge of shield wall in front of the antennal insertions (Myrmecina vieti complex) . . . . . 2
• Lateral portions of clypeus not raised into a sharp ridge of shield wall in front of the antennal insertions . . . . . 4

2

return to couplet #1

• Petiole longer than high; lateral surface smooth; ventral margin concave in profile . . . . . Myrmecina vieti

• Petiole as long as high; lateral surface rugose; ventral margin not concave in profile . . . . . 3

3

return to couplet #2

• Body color reddish brown. Anterior portion of postpetiole forming more or less distinct lateral expansion, broadest anteriorly and much broader than petiole. Mesosoma with more or less flattened dorsal margin in profile; dorsal surface with longitudinal and parallel rugae . . . . . Myrmecina nomurai

• Body color black. Anterior portion of postpetiole not expanded laterally, slightly broader than petiole. Mesosoma with convex dorsal margin in profile; dorsal surface with rugae diverging anteriorly . . . . . Myrmecina guangxiensis

4

return to couplet #1

• Occipital corners of head projected posteriorly (Myrmecina spinosa complex) . . . . . 5
• Occipital corners of head not projected posteriorly . . . . . 10

5

return to couplet #4

• First gastral tergum not concave in dorsal view . . . . . 6
• First gastral tergum concave in dorsal view . . . . . 7

6

return to couplet #5

• Mesosoma in lateral view with dorsal outline evenly convex. Mesosoma with irregular longitudinal rugulae. Propodeal spine pointing dorsally . . . . . Myrmecina andalas

• Mesosoma in lateral view with dorsl outline highly convex. Mesosoma with irregular rugulae. Propodeal spine pointing posteriorly . . . . . Myrmecina mahuana

7

return to couplet #5

• Masticatory margin of mandible straight . . . . . Myrmecina inflata

• Masticatory margin of mandible bent at midlength . . . . . 8

8

return to couplet #7

• Propodeal spine elevated, pointing dorsally; propodeal declivity almost vertical with posterodorsal angle about 90˚ . . . . . Myrmecina magnificens

• Propodeal spine extending backward and over vertical posteriormost limit of propodeum in profile; propodeal declivity steep with posterodorsal angle < 90˚ . . . . . 9

9

return to couplet #8

• Head and mesosoma with straight and longitudinal rugae on dorsal surface. Postpetiole distinctly marginate, sometimes with projected lateral lobe on both sides in dorsal view; anterior dorsal margin angulately raised in profile . . . . . Myrmecina spinosa

• Head and mesosoma with wavy or irregular rugae on dorsal surface, sometimes the rugae on mesosoma transverse. Postpetiole not marginate on both sides in dorsal view; anterior dorsal margin not angulately raised, almost horizontal in profile . . . . . Myrmecina tridentata

10

return to couplet #4

• Head smooth and shining, or sparsely foveate on dorsal surface . . . . . 11
• Head largely sculptured with rugae and sometimes dense punctures on dorsal surface . . . . . 15

11

return to couplet #10

• Head longer than broad . . . . . Myrmecina glabra

• Head as long as broad (Myrmecina macrops complex) . . . . . 12

12

return to couplet #11

• Propodeal spine only angulately projected, not spine-like . . . . . Myrmecina breviata

• Propodeal spine well developed, triangular to elongate . . . . . 13

13

return to couplet #12

• Head sparsely foveate on dorsal surface . . . . . Myrmecina macrops

• Head smooth and shining, or mostly smooth and shining except for frontal carinae and few rugulae in front of eye . . . . . 14

14

return to couplet #13

• Mesosoma with straight rugulae in dorsal view; median longitudinal portion raised, forming arched surface . . . . . Myrmecina gymnocephala

• Mesosoma with wavy rugulae in dorsal view . . . . . Myrmecina nitidiuscula

15

return to couplet #10

• Anterior margin of first gastral tergum more or less concave in dorsal view . . . . . 16
• Anterior margin of first gastral tergum not concave in dorsal view . . . . . 20

16

return to couplet #15

• First gastral tergum sculptured ( Myrmecina gracilis complex) . . . . . 2
• First gastral tergum not sculptured . . . . . 19

17

return to couplet #16

• First gastral sternum not sculptured . . . . . Myrmecina curvispina

• First gastral sternum sculptured . . . . . 18

18

return to couplet #17

• First gastral sternum with ridge at anterior median portion in ventral view. Anterior clypeal margin without single median process. Head longer than broad . . . . . Myrmecina gracilis

• First gastral sternum without ridge at anterior median portion in ventral view. Anterior clypeal margin with single median process. Head as long as broad . . . . . Myrmecina raviwonghei

19

return to couplet #16

• Propodeal spine broad and triangular, 1.5 times as long as broad at base or shorter, just reaching vertical posteriormost limit of propodeum in profile. Pronotum with rugae on dorsal surface. Eye comprising 15 ommtidia or more . . . . . Myrmecina aspera

• Propodeal spine elongate, much longer than broad at base, extending over vertical posteriormost limit of propodeum in profile. Pronotum smooth and shining on dorsal surface. Eye comprising 10 ommatidia or less . . . . . Myrmecina elegans

20

return to couplet #15

• Antennal scape long, extending beyond occipital corner in full-face view . . . . . 21
• Antennal scape short, not or just reaching occipital corner in full-face view . . . . . 31

21

return to couplet #20

• Eumetanotal spine absent . . . . . 22
• Eumetanotal spine present . . . . . 23

22

return to couplet #21

• Anterior clypeal margin without processes . . . . . Myrmecina dolichothrix

• Anterior clypeal margin with three processes . . . . . Myrmecina gopa

23

return to couplet #21

• Ventral portion of petiole simple, without subpetiolar process nor median longitudinal ridge . . . . . 24
• Ventral portion of petiole with subpetiolar process or median longitudinal ridge . . . . . 28

24

return to couplet #23

• Anterior clypeal margin with median paired processes . . . . . 25
• Anterior clypeal margin with single median process or without processes . . . . . 26

25

return to couplet #24

• Head with straight and thick rugae on dorsal surface. Forecoxa with rugae . . . . . Myrmecina boltoni

• Head with slightly waved and thin rugae, and punctures on dorsal surface. Forecoxa smooth and shining . . . . . Myrmecina monticola

26

return to couplet #24

• Propodeal spine long, extending over vertical posteriormost limit of propodeum in profile . . . . . Myrmecina parallela

• Propodeal spine short, not or just reaching vertical posteriormost limit of propodeum in profile . . . . . 27

27

return to couplet #26

• Pronotal pilosity sparse and extremely long, almost three times as long as propodeal spine. Dorsal portion of propodeal lobe not raised, simple. Ventrolateral portion of head sculptured. Eye much shorter than malar space . . . . . Myrmecina longiseta

• Pronotal pilosity dense and short, twice as long as propodeal spine or shorter. Dorsal portion of propodeal lobe raised, forming rounded corner. Ventrolateral portion of head smooth and shining. Eye as long as malar space . . . . . Myrmecina bandarensis

28

return to couplet #23

• Ventrolateral portion of head sculptured . . . . . 29
• Ventrolateral portion of head smooth and shining . . . . . 30

29

return to couplet #28

• Anterior clypeal margin with single median process. Mesosoma with straight and parallel rugae on dorsal surface. Eye comprising 20 ommatidia or more . . . . . Myrmecina inthanonensis

• Anterior clypeal margin with three processes. Mesosoma with wavy and diverging rugae on dorsal surface. Eye comprising 15 ommatidia or less . . . . . Myrmecina nigra

30

return to couplet #28

• Eye small, comprising 15 ommatidia or less; the diameter much shorter than half of malar space. Head longer than broad (CI <90) . . . . . Myrmecina muluensis

• Eye large, comprising 20 ommatidia or more; the diameter longer than half of malar space. Head as long as broad (CI≥98) . . . . . Myrmecina sulcata

31

return to couplet #20

• Pilosity extremely dense; number of hairs on petiole more than 20 . . . . . Myrmecina dasynota

• Pilosity sparse; number of hairs on petiole less than 15 . . . . . 32

32

return to couplet #31

• Mesosoma with transverse rugae on dorsal surface . . . . . 33
• Mesosoma with longitudinal or irregular rugae on dorsal surface . . . . . 34

33

return to couplet #32

• Propodeal spine long, pointed backward . . . . . Myrmecina dechai

• Propodeal spine short, pointed upward . . . . . Myrmecina poringensis

34

return to couplet #32

• Dorsal median portion of mesosoma and lateral portion of pronotum not sculptured . . . . . Myrmecina lambirensis

• Dorsal median portion of mesosoma and lateral portion of pronotum sculptured . . . . . 35

35

return to couplet #34

• First gastral sternum sculptured . . . . . Myrmecina celebensis

• First gastral sternum not sculptured . . . . . 36

36

return to couplet #35

• First gastral tergum sculptured . . . . . Myrmecina sundanica

• First gastral tergum smooth and shining . . . . . 37

37

return to couplet #36

• Eye distinctly longer than half of malar space . . . . . 38
• Eye as long as or shorter than half of malar space . . . . . 40

38

return to couplet #37

• Head broad posteriorly in full-face view. Petiole distinctly longer than high in profile. Rugae on dorsal surface of head running parallel and straight . . . . . Myrmecina padangensis

• Head with lateral margins nearly parallel in full-face view, anterior width almost same as posterior one. Petiole almost as long as high in profile. Rugae on dorsal surface of head running wavy and irregularly . . . . . 39

39

return to couplet #38

• Masticatory margin of mandible straight without basal tooth . . . . . Myrmecina itoi
• Masticatory margin of mandible bent at the midlength with basal tooth . . . . . Myrmecina maryatiae

40

return to couplet #37

• Masticatory margin of mandible straight . . . . . Myrmecina grandis
• Masticatory margin of mandible bent at midlength . . . . . 41

41

return to couplet #40

• Rugae on ventrolateral portion of head transverse . . . . . Myrmecina insulana
• Rugae on ventrolateral portion of head longitudinal or absent . . . . . 42

42

return to couplet #41

• Antennal scape not reaching occipital corner by scape width in full-face view (SI≤77) . . . . . Myrmecina yamanei
• Antennal scape just reaching occipital corner in full-face view (SI≥80) . . . . . 43

43

return to couplet #42

• Anterior clypeal margin with median paired processes . . . . . Myrmecina sabahna
• Anterior clypeal margin with single median process or without processes . . . . . 44

44

return to couplet #43

• Ventrolateral portion of head with punctures, without longitudinal rugae . . . . . 45
• Ventrolateral portion of head without punctures, or with both punctures and longitudinal rugae . . . . . 46

45

return to couplet #44

• Eye small and circular, comprising about 6 ommatidia; the diameter much shorter than half of malar space. Head longer than broad . . . . . Myrmecina asthena
• Eye medium-sized and oval, comprising about 14 ommatidia; the diameter as long as half of malar space. Head as long as broad . . . . . Myrmecina lombokensis

46

return to couplet #44

• Eye small and circular, comprising about 9 ommatidia; its diameter much shorter than half of malar space . . . . . Myrmecina asiatica
• Eye medium-sized and oval, comprising 15 ommatidia or more; its diameter as long as half of malar space . . . . . Myrmecina sulawesiana