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Key to Brachyponera species
These keys to species groups and species (below) of Brachyponera are based on workers and have been provided by Chen et al. (2025).
Key to species groups of Brachyponera based on workers.
1
- Lateral face of pronotum with transverse rugae => Brachyponera atrata group
- Lateral face of pronotum smooth and shiny or only punctate => 2
2
return to couplet #1
- In full-face view, head broader than long => Brachyponera lutea group (part)
- In full-face view, head longer than broad => 3
3
return to couplet #2
- In full-face view, eye small, with five ommatidia along longest axis (ED 0.07 mm) (China) => Brachyponera kumtongi group
- In full-face view, eye moderately large, with more than nine ommatidia along longest axis (ED > 0.15 mm) => 4
4
return to couplet #3
- In lateral view, propodeum densely transversely rugose; smooth area if any much restricted => Brachyponera chinensis group
- In lateral view, propodeum smooth or only punctate => 5
5
return to couplet #4
- In dorsal view, lateral margin of pronotum with well-defined edge; lateral slope of pronotum nearly vertical => Brachyponera xui group
- In dorsal view, lateral margin of pronotum not well defined; lateral slope of pronotum convex => 6
6
return to couplet #5
- In lateral view, dorsal surface of propodeum continuously connected with declivity, forming complete circular arc => 7
- In lateral view, dorsal surface of propodeum clearly differentiated from declivity; posterodorsal corner of propodeum roundly angled => 8
7
return to couplet #6
- Larger species, > 5 mm in total body length; antenna scape long, > 1/5 exceeds posterolateral corner; in lateral view, pronotum weakly convex => Brachyponera arcuata group
- Smaller species, < 4 mm in total body length; antenna scape short, slightly exceeds posterolateral corner; in lateral view, pronotum relatively flat => Brachyponera lutea group (part)
8
return to couplet #6
- Larger species, > 4.5 mm in total body length; head width > 0.9 mm; flagellar segments 1 and 2 longer than broad; body color usually dark brown => Brachyponera nigrita group
- Smaller species, < 4.5 mm in total body length; head width < 0.9 mm; flagellar segments 1 and 2 each as long as broad, or broader than long; body color usually yellowish brown to tan => Brachyponera obscurans group
Key to Brachyponera species based on the worker caste.
The distinction between the four species, Brachyponera flavipes, Brachyponera batak, Brachyponera pilidorsalis and Brachyponera nigrita is principally based on Yamane (2007). The subspecies Brachyponera nigrita nigritella is not included.
1
- Lateral face of pronotum with transverse rugae (Fig. 2A, B) => 2
- Lateral face of pronotum smooth and shiny or only punctate (Fig. 2C, D) => 3
Chen et al. (2025), Figure 2. Mesosoma in profile showing sculpture of lateral face of pronotum. A, Brachyponera atrata (CASENT0178452). B, B. wallacea (non-type). C, B. chinensis (CASENT0903937, type). D, B. luteipes (CASEN0915672, type). Photographers April Nobile (A), Chao Chen (B), Will Ericson (C), Harald Bruckner (D).
,_Fig._2.jpg)
2
return to couplet #1
- Dorsum of propodeal declivity with rugae only on upper part (Fig. 3A); in lateral view, propodeum with sparsely transverse rugae (Fig. 3C) (Maluku islands) => Brachyponera atrata
- Dorsum of propodeal declivity with rugae on middle and upper parts (Fig. 3B); in lateral view, propodeum with densely transverse rugae (Fig. 3D) (Sulawesi, Lombok, and Bali) => Brachyponera wallacea
,_Fig._3.jpg)
3
return to couplet #1
- Eye small with 2–5 ommatidia along longest axis (ED 0.07 mm) (Fig. 4A, B) => 4
- Eye moderately large, with > 7 ommatidia along longest axis (ED > 0.10 mm) (Fig. 4C, D) => 5
,_Fig._4.jpg)
4
return to couplet #3
- Eye very small, present as a dot, with 2 or 3 ommatidia along longest axis (Fig. 4B); antennal segments 3 and 4 each as long as broad, or broader than long; body color reddish brown (Thailand) => Brachyponera kumtongi
- Eye relatively small, with 4 or 5 ommatidia along longest axis (Fig. 4A); antennal segments 3 and 4 each longer than broad; body color brownish black (China) => Brachyponera myops
5
return to couplet #3
- In full-face view, head broader than long, or almost as long as broad (Fig. 5A, B) => 6
- In full-face view, head longer than broad (Fig. 5C, D) => 7
,_Fig._5.jpg)
6
return to couplet #5
- Posterior margin of head in in full-face view strongly concave; scape long, slightly extending beyond posterolateral corner of head; eye large (Fig. 5A); body color dark brown (Fig. 6A) (Central to Southern Africa) => Brachyponera sennaarensis
- Posterior margin of head in full-face view weakly concave; scape short, not reaching posterolateral corner of head; eye small (Fig. 5B); body color yellow brown (Fig. 6B) (Australia) => Brachyponera lutea
,_Fig._6.jpg)
7
return to couplet #5
- In lateral view, propodeum densely transversely or irregularly rugose (Fig. 7A, B) => 8
- In lateral view, propodeum smooth or only punctate (Fig. 7C, D) => 9
,_Fig._7.jpg)
8
return to couplet #7
- In dorsal view, petiolar node broader (PDPI 175) (Fig. 8A, B) (Japan) => Brachyponera nakasujii
- In dorsal view, petiolar node narrow (PDPI 130) (Fig. 8C, D) (China, North Korea, South Korea, Japan, Vietnam, Thailand, Nepal) => Brachyponera chinensis
,_Fig._8.jpg)
9
return to couplet #7
- In dorsal view, lateral margin of pronotum markedly edged; lateral face of pronotum nearly vertical (Fig. 9A) (China) => Brachyponera xui
- In dorsal view, lateral margin of pronotum without well-defined edges; lateral faces of pronotum diverging downward, appearing more convex (Fig. 9B) => 10
,_Fig._9.jpg)
10
return to couplet #9
- In lateral view, dorsal surface of propodeum continuously connected with declivity, forming complete circular arc (Fig. 10A) => 11
- In lateral view, dorsal surface of propodeum and declivity separated by roundly-angled posterodorsal corner (Fig. 10B) => 14
,_Fig._10.jpg)
11
return to couplet #10
- Smaller species; TL < 4 mm (Fig. 11A); HW < 0.80 mm => 12
- Larger species; TL > 5 mm (Fig. 11B); HW > 0.80 mm => 13
,_Fig._11.jpg)
12
return to couplet #11
- Clypeal median lobe relatively long; frontal carina relatively long, reaching anterior to mid-length of head; body entirely yellowish brown (Thailand) => Brachyponera troglomorpha
- Clypeal median lobe relatively short; frontal carina relatively short, reaching level posterior margin of eye; body entirely black => Brachyponera brevidorsa
13
return to couplet #11
- In full-face view, outline between mandibular base and anterior margin of eye (malar space) strongly convex (Fig. 12A); in lateral view, propodeal declivity rugose at margin; in posterior view propodeal declivity laterally weakly margined, transversely rugose except for median smooth area; rugae extending to posterior portion of lateral face of propodeum (Fig. 12B); body color brownish yellow (New Guinea, Java) => Brachyponera arcuata
- In full-face view, outline between mandibular base and anterior margin of eye (malar space) nearly straight (Fig. 12C); in lateral view, propodeal declivity smooth at margin; in posterior view propodeal declivity smooth (Fig. 12D); body color black to brownish black (China) => Brachyponera paraarcuata
,_Fig._12.jpg)
14
return to couplet #10
- Large species, TL > 4.5 mm, HW > 0.9 mm; antennal segments 3 and 4 each longer than broad (Fig. 13A, B); body color usually dark brown => 15
- Small-sized species, TL < 4.5 mm, HW < 0.9 mm; antennal segments 3 and 4 each as long as broad, or broader than long (Fig. 13C, D); body color usually yellowish brown to tan => 19
,_Fig._13.jpg)
15
return to couplet #14
- Petiolar node thick (PL > 0.40 mm); in dorsal view, petiole long trapezoidal shape (Fig. 14A) (China) => Brachyponera candida
- Petiolar node thin (PL < 0.40 mm); in dorsal view, petiole semicircular or short trapezoid (Fig. 14B-D) => 16
,_Fig._14.jpg)
16
return to couplet #15
- Antennal scape shorter, surpassing posterior margin of head by < 1/4 of its length; legs yellowish brown to orangish, contrasting with jet black mesosoma (Fig. 15A) (Myanmar) => Brachyponera flavipes
- Antennal scape longer, surpassing posterior margin of head by > 1/4 of its total length; legs brown to dark brown, contrast with body color weaker (Fig. 15B) => 17
,_Fig._15.jpg)
17
return to couplet #16
- Standing hairs on mesosomal dorsum absent or very few; standing hairs if any generally shorter than width of antennal segment 3 (Fig. 16A) (Sumatra) => Brachyponera batak
- Mesosomal dorsum usually with > 10 standing hairs, some of which are as long as or longer than width of antennal segment 3 (Fig. 16B) => 18
,_Fig._16.jpg)
18
return to couplet #17
- Mesopleuron often with transverse groove; groove sometimes incomplete but at least scar visible (Fig. 17A); posterior faces of propodeum and petiole more strongly punctate (Fig. 17C); gastral tergite 1 usually with > 10 standing hairs (Fig. 17C) (Borneo; Malay Peninsula, Java) => Brachyponera pilidorsalis
- Mesopleuron usually without such groove; groove if any vestigial (Fig. 17B); posterior face of propodeum medially and petiole entirely smooth or very weakly punctate (Fig. 17D); gastral tergite 1 with fewer standing hairs, the number, excluding those on posterior margin of tergite, being usually less than ten (Fig. 17D) (China, Philippines, Vietnam, Thailand, Myanmar, Sumatra, India, Nepal) => Brachyponera nigrita
,_Fig._17.jpg)
19
return to couplet #14
- In dorsal view, gastral tergite 1 with densely sub-decumbent hairs (Fig. 18A, B) => 20
- In dorsal view, gastral tergite 1 with sparsely sub-decumbent hairs or fewer standing hairs (Fig. 18C, D) => 21
Chen et al. (2025), Figure 18. Gastral in dorsal view. A, Brachyponera jerdonii (CASENT0907282, type). B, B. christmasi (CASENT0902496, type). C, B. luteipes (CASENT0915672, type). D, B. croceicornis (CASENT0907286, type). Photographers Z. Lieberman (type) (A, D), Will Ericson (B), Harald Bruckner (C).
,_Fig._18.jpg)
20
return to couplet #19
- Eye small, with maximum width of scape accounting for 83% of the longest axis of eye; body color reddish brown (Fig. 19A) (Vietnam, Sri Lanka, India) => Brachyponera jerdonii
- Eye moderately large, with maximum width of scape accounting for 65% of the longest axis of eye; body color tan (Fig. 19B) (Christmas Island) => Brachyponera christmasi
,_Fig._19.jpg)
21
return to couplet #19
- In lateral view, dorsal surface of propodeum convex (Fig. 20A) (China, Vietnam, Laos, Thailand, Myanmar, India, Sri Lanka, Sumatra, Philippines, Borneo, Sulawesi, Java) => Brachyponera luteipes
- In lateral view, dorsal surface of propodeum concave or almost straight (Fig. 20B, C) => 22
,_Fig._20.jpg)
22
return to couplet #21
- Upper part of propodeum with sparsely sub-decumbent hairs; body color reddish brown (Fig. 20B) (Australia, New Guinea) => Brachyponera croceicornis
- Upper part of propodeum with densely sub-decumbent hairs; body color dark brown (Fig. 20C) (China, Philippines, Borneo, Malaysia, Singapore, India, Sri Lanka) => Brachyponera obscurans
References
Chen, C., Yu, Y., Yi, C. 2025. Revision of the Chinese species of the genus Brachyponera Emery, 1900 (Hymenoptera, Formicidae), with a key to the world species of the genus. ZooKeys 1230: 247-286. (doi:10.3897/zookeys.1230.140159).