Key to southeastern Asian Aenictus ceylonicus group species

Key to Asian Aenictus ceylonicus group species based on workers, modified from Jaitrong & Yamane (2013), Liu et al. (2015) and Staab (2015) by Dhadwal & Bharti (2023).

1

 * Mandible with 2-6 teeth/denticles between subapical and basal teeth (mandible with more than 4 teeth/denticles) (Fig. 5a)
 * Mandible with 0-1 tooth/denticle between subapical and basal teeth (mandible with 3-4 teeth/denticles) (Fig. 5b)

2

 * Promesonotum entirely sculptured (punctate or reticulate)
 * Promesonotum largely smooth and shiny

3

 * Promesonotum sparsely reticulate or superficially micropunctate; antennal scape superficially shagreened; petiole cylindrical, clearly longer than high (Fig. 6a) Aenictus cylindripetiolus
 * Promesonotum densely punctate; antennal scape micropunctate; petiole round or subangular, almost as long as high (Fig. 6b) Aenictus thailandianus

4

 * Subpetiolar process prominent
 * Subpetiolar process not prominent, weakly developed

5

 * Dorsum of mesonotum and petiole finely reticulate
 * Dorsum of mesonotum and petiole smooth and shiny

6

 * Subpetiolar process rectangular-trapezoidal, its ventral outline with a thin almost transparent lamellae (Fig. 7a); masticatory margin of mandible with 4 (rarely 3) denticles (total number of mandibular teeth 6-7, including apical, subapical, and basal tooth) Aenictus hoelldobleri
 * Subpetiolar process rectangular, its apex very acute and directed downwards medially (Fig. 7b); masticatory margin of mandible with 6 denticles (total number of mandibular teeth 9 including apical, subapical, and basal tooth) Aenictus wudangshanensis

7

 * Metanotal groove distinct; lateral propodeal margins converge more sharply posterad; pospetiole convex in profile; subpetiolar process subrectangular with acute anterior corners and blunt posterior corners (Fig. 8a, b) Aenictus dirangensis


 * Metanotal groove weakly impressed; lateral propodeal margins gently sloping posteriorly; pospetiole angular in profile; subpetiolar process relatively elongated, and slightly projecting anteroventrally (Fig. 8c, d) Aenictus yangi

8

 * Dorsal face of propodeum mostly smooth and shiny, the lateral face of propodeum partly smooth and shiny; postpetiole entirely smooth and shiny (Fig. 9a)
 * Propodeum entirely sculptured; postpetiole entirely sculptured or with a smooth and shiny small area on the dorsal face (Fig. 9b)

9

 * The declivity of propodeum with lateral carinae, but not demarcated basally by a transverse carina (Fig. 10a) Aenictus longicephalus
 * The declivity of propodeum is shallowly concave, encircled with a rim (Fig. 10b)

10

 * Distal 2/3 of basal margin of mandible straight, proximal 1/3 narrowed toward the base of mandible; anterior clypeal margin straight; petiole smaller than postpetiole (Fig. 11a, b) Aenictus minipetiolus
 * Basal margin of mandible feebly concave; anterior clypeal margin concave; petiole larger than or as large as postpetiole (Fig. 11c, d)

11

 * Promesonotum is strongly convex and sloping gradually to the metanotal groove; subpetiolar process with angular posteroventral corner (Fig. 12a) Aenictus baliensis
 * Mesosoma almost flat dorsally or feebly convex; subpetiolar process lower, with its posteroventral corner rounded (Fig.12b) Aenictus wiwatwitayai

12

 * Vertex with sparse standing hairs and with a few short appressed hairs; promesonotum with few appressed hairs and a few decumbent hairs (Fig. 13a)


 * Vertex and promesonotum with dense standing or decumbent hairs (Fig. 13b)

13

 * Vertex with two long-standing hairs mixed with a few short appressed hairs Aenictus appressipilosus
 * Vertex with only few short appressed hairs Aenictus malakkaparensis

14

 * Occipital corner modified into a small lobe in profile and dorsal view (Fig. 14a) Aenictus gonioccipus
 * Occipital corner without modifications in profile and dorsal view (Fig. 14b)

15

 * Mesonotum straight in dorsally slope down backward; posterodorsal corners of propodeum protruding and dentate, declivity concave Aenictus henanensis
 * Mesonotum weakly or strongly convex in dorsal outline; posterodorsal corners of propodeum angular nearly right-angled, declivity shallowly concave

16

 * Masticatory margin of mandible with large acute apical tooth followed by a series of 6-7 denticles of two sizes, the larger alternating with 1-2 smaller; the gap between anterior clypeal margin and mandibles relatively small or indistinct, with maximum width shorter than the maximum width of the mandible (Fig. 15a) Aenictus lifuiae
 * Masticatory margin of mandible with large acute apical tooth followed by a medium-sized subapical tooth, 2-5 denticles, and a medium-sized basal tooth; the gap between anterior clypeal margin and mandibles relatively large and distinct, with maximum width longer than the maximum width of the mandible (Fig. 15b)

17

 * Subpetiolar process subtriangular, its apex directed backward, anteroventrally not angular; postpetiole elevated posteriorly; its posterior face much steeper than anterior face (Sumatra) (Fig. 16a) Aenictus itoi


 * Subpetiolar process subrectangular, its apex directed forward, anteroventrally angular; postpetiole with roundly convex dorsal outline (Fig.16b, c)

18

 * Subpetiolar process rectangular, ventrally with anterior and posterior corners
 * Subpetiolar process low, its ventral outline convex, almost straight or feebly concave, and anteroventral corner acutely angular

19

 * Dorsal outline of propodeum weakly convex; metapleural gland bulla weakly sculptured (Vietnam) Aenictus eguchii
 * Dorsal outline of propodeum straight; metapleural gland bulla strongly sculptured (puncto-reticulate)

20

 * Posteroventral corner of subpetiolar process angular (not spiniform) Aenictus kodungallurensis
 * Posteroventral corner of subpetiolar process acutely produced ventrally (spiniform) Aenictus jawadwipa

21

 * Promesonotum in profile weakly convex; propodeal dorsum feebly convex; petiole sessile, its posterior face encircled with a thin carina; postpetiole almost as long as petiole (Fig. 17a) Aenictus wilaiae
 * Promesonotum in profile strongly convex and forming a dome; propodeal dorsum clearly straight; petiole subsessile, its posterior face not encircled with a carina; postpetiole slightly shorter than petiole (Philippines) (Fig. 17b) Aenictus pilosus

22

 * Mandible with 3 teeth including apical and basal teeth (Fig. 18a)
 * Mandible with 4 teeth including apical and basal teeth (Fig. 18b)

23

 * Occipital corner rounded in lateral view; promesonotum in profile strongly convex and forming a dome; petiole almost as long as high, with high node, and almost as long as postpetiole (Fig. 19a) Aenictus watanasiti
 * Occipital corner shallowly rounded in lateral view; promesonotum in profile with weakly convex or almost flat dorsal outline; petiole clearly longer than high, with low node, and slightly longer than postpetiole Fig. 19b) Aenictus concavus

24

 * Dorsal and lateral faces of pronotum largely smooth and shiny; petiole almost as long as high; head slightly longer than or almost as long as broad (CI 90- 100) (Fig. 20a)
 * Dorsal and lateral faces of pronotum entirely sculptured (superficially puncto-reticulate, punctate to reticulate); petiole cylindrical, distinctly longer than high; head slightly shorter than broad (CI 102-112) (Fig. 20b)

25

 * Anterior clypeal margin distinctly concave; metanotal groove distinct, deep; foretibia relatively short, its length less than 0.5 times of head width; mesopleuron finely punctate without longitudinal rugulae (Fig. 21a) Aenictus brevipodus
 * Anterior clypeal margin almost straight or feebly concave; metanotal groove indistinct; foretibia relatively long, its length about 0.9-1.0 times as long as head width; mesopleuron with longitudinal rugulae (Fig. 21b)

26

 * Subpetiolar process low, ventral outline weakly convex, its anteroventral corner angular (Thailand) (Fig. 22a) Aenictus khaoyaiensis
 * Subpetiolar process well-developed, subrectangular with a convex ventral lamella, with anterior corners acute and posterior corners bluntly angular (Fig. 22b) Aenictus formosensis

27

 * Subpetiolar process very low, with anterior and posterior denticles that protrude anteroventrally; head in full-face view rectangular, its posterior margin feebly concave (Thailand) (Fig. 23a, b) Aenictus maneerati
 * Subpetiolar process subrectangular or low, with its anteroventral corner acutely angular and ventral outline straight or convex; head in full-face view subrectangular or rounded, its posterior margin weakly concave, almost straight or weakly convex (Fig. 23c, d)

28

 * Pronotum with central area superficially shagreened or rather smooth and shining, and with lateral face reticulate and shiny; subpetiolar process low, with its anteroventral corner acutely angular and ventral outline concave (Fig. 24a) Aenictus sundalandensis
 * Pronotum micropunctate or reticulate and opaque (at most weakly shining); subpetiolar process always low, with its anteroventral corner acutely angular and ventral outline almost straight or convex (Fig. 24b)

29

 * Pronotum entirely strongly punctate (N. Thailand) (Fig. 25a) Aenictus pinkaewi
 * Anterior portion of the pronotum densely punctate, the lateral face of the pronotum finely reticulate (China, Hong Kong, Laos and Thailand) (Fig. 25b) Aenictus fuchuanensis