Key to Carebara of China

Key to Carebara species of China based on major worker caste (modified from Liu et al., 2023).

This key is based on Xu (2003) and Zhou et al. (2006), including 34 species and subspecies; some illustrations of the key were drawn from Xu (2003) and Terayama (1996). The following species are excluded from this key because descriptions of the major workers are unavailable: Carebara amia, Carebara castanea and Carebara lignata. Some distribution data about Chinese Carebara species in previous studies are ambiguous. After verification with Xu (pers. comm. July 21, 2023), some records are not accepted in this study and the following species are excluded from the Chinese fauna: Carebara asina, Carebara bengalensis, Carebara bruni, Carebara cribriceps and Carebara pumilia.

1

Antenna 11-segmented (Fig. 2A) => 2
Antenna 9- or 10-segmented (Fig. 2B, C) => 17

Liu, Z., Zhong, Y. et al. (2024), Figure 2. Antenna. A, 11-segmented. B, 9-segmented. C, 10-segmented.

2

return to couplet #1

Worker caste polymorphic, with continuous series of intermediates between minor and largest major worker => 3
Worker caste dimorphic => 13

3

return to couplet #2

Propodeal spines long, > 1/2 of the distance between the base of two spines (Fig. 3A) => 4
Propodeal spines short, < 1/3 of the distance between the base of 2 spines (Fig. 3B) => 9

Liu, Z., Zhong, Y. et al. (2024), Figure 3. Mesosoma. A, longer spine. B, shorter spine.

4

return to couplet #3

Largest major worker with mesoscutellum strongly convex in lateral view and with single ocellus on the front of head (Fig. 4A, C) => 5
Largest major worker with mesoscutellum broadly convex in lateral view and with no ocelli on the front of head (Fig. 4B, D) => 7

Liu, Z., Zhong, Y. et al. (2024), Figure 4. Head in full-face view and mesosoma in lateral view (the largest major worker). A, head with an ocellus. B, head with no ocelli. C, mesoscutellum strongly convex. D, mesoscutellum broadly convex.

5

return to couplet #4

Largest major worker distinctly smaller with TL 11–12 mm => Carebara diversa draco
Largest major worker distinctly larger with TL ~ 16 mm => 6

6

return to couplet #5

The posterior quarter of the head with transverse and very large wrinkles; the smooth frontal space more extensive (Fig. 5A) => Carebara diversa laotina
The posterior 1/3 of head with diverged wrinkles; smooth frontal space more narrowed (Fig. 5B) => Carebara diversa

Liu, Z., Zhong, Y. et al. (2024), Figure 5. Heads of Carebara diversa and Carebara diversa laotina in full-face view (the largest major worker). A, C. diversa laotina, head with broader smooth space, wrinkles mostly transverse. B, C. diversa, head with more narrowed smooth space, wrinkles fine and diverged.

7

return to couplet #4

Propodeal spines curving forward and inclined (Fig. 6A) => Carebara yanoi
Propodeal spines directed backwards or erect (Fig. 6B) => 8

Liu, Z., Zhong, Y. et al. (2024), Figure 6. Pronotal spines. A, curving forward. B, backwards.

8

return to couplet #7

Promesonotum slightly convex in lateral view; first tergite of gaster > 2× as wide as second tergite => Carebara nanningensis
Promesonotum distinctly convex in lateral view; first gastric tergum almost as wide as second tergum => Carebara affinis

9

return to couplet #3

Head and body mostly smooth and shiny (Fig. 7A) => 10
Head and body coarsely striate (Fig. 7B) => 12

Liu, Z., Zhong, Y. et al. (2024), Figure 7. Head in full-face view. A, head mostly smooth and shiny. B, head mostly striate.

10

return to couplet #9

Propodeal spines pointing backwards in the largest major worker; petiolar node broadly rounded above in profile view; head without a coarse black line in median longitudinal groove (Fig. 8A, C) => Carebara latinoda
Propodeal spines curving forward in the largest major worker; petiolar node narrowed above, triangular in profile view; head with a coarse black line in median longitudinal groove (Fig. 8B, D) => 11

Liu, Z., Zhong, Y. et al. (2024), Figure 8. Head in full-face view, mesosoma and petiole in lateral view. A, head without a coarse black line. B, head with a coarse black line in median longitudinal groove. C, propodeal spines pointing backward, petiolar node round above. D, propodeal spines curving forward, petiolar node narrowed above.

11

return to couplet #10

Postpetiole approximately as long as wide; hairs sparse (Fig. 9A, C) => Carebara vespillo
Postpetiole distinctly broader than long; hairs abundant (Fig. 9B, D) => Carebara melasolena

Liu, Z., Zhong, Y. et al. (2024), Figure 9. Head and mesosoma in lateral view, postpetiolar node in dorsal view. A, C. vespillo, hairs sparse. B, C. melasolena, hairs abundant. C, C. vespillo, postpetiolar node nearly as long as wide. D, C. melasolena, postpetiolar node distinctly wider than long.

12

return to couplet #9

Propodeal spines laterally compressed and curving forward; mandibles with longitudinal striations on the base in full-face view; interspaces on the head between striations punctured (Fig. 10A, C) => Carebara trechideros
Propodeal spines thick and straight, not curved; mandibles smooth in fullface view; interspaces between striations smooth (Fig. 10B, D) => Carebara zengchengensis

Liu, Z., Zhong, Y. et al. (2024), Figure 10. Head in full-face view and mesosoma in lateral view (the largest major worker). A, head of C. trechideros, mandibles with longitudinal striations, interspaces between triations punctured. B, head of C. zengchengensis, mandibles without striations, interspaces between striations smooth. C, propodeal spines curving forward. D, propodeal pines straight and not curved.

13

return to couplet #2

Mandible with 5 teeth on masticatory margin (Fig. 11A) => 14
Mandible with 6 teeth on masticatory margin (Fig. 11B) => 16

Liu, Z., Zhong, Y. et al. (2024), Figure 11. Mandibles. A, mandible with 5 teeth. B, mandible with 6 teeth.

14

return to couplet #13

Posterolateral corners of head with minute tubercles; eyes present; head slightly longer than wide (Fig. 12A) => Carebara altinodus
Posterolateral corners of head with developed horns; eyes absent; head distinctly longer than wide (Fig. 12B) => 15

Liu, Z., Zhong, Y. et al. (2024), Figure 12. Horns. A, posterolateral corners of head with minute tubercles. B, posterolateral corners of head with developed horns.

15

return to couplet #14

Head broader behind than in front with more punctures; head and thorax ith dense hairs => Carebara capreola
The posterior portion of head almost as wide as the anterior portion; ead with less punctures, smoother and more shiny; head and thorax with parser and shorter hairs => Carebara capreola

16

return to couplet #13

Eyes absent; propodeal denticles downwardly inclined; first segment of aster finely punctuate (Fig. 13A) => Carebara curvispina
Eyes present; propodeal denticles dorsoposteriorly pointed; first segment f gaster densely longitudinally striate (Fig. 13B) => Carebara striata

Liu, Z., Zhong, Y. et al. (2024), Figure 13. Two Carebara species in lateral view A, C. curvispina, propodeal denticles down-inclined, first segment of gaster finely punctuate, eyes absent. B, C. striata, propodeal denticles dorsoposteriorly pointed, first segment of gaster densely longitudinally triate, eyes present.

17

return to couplet #1

Mandible with 6 teeth on masticatory margin (Fig. 14C) => 18
Mandible with 4 or 5 teeth on masticatory margin (Fig. 14A, B) => 19

Liu, Z., Zhong, Y. et al. (2024), Figure 14. The number of teeth. A, 4-teethed. B, 5-teethed. C, 6-teethed.

18

return to couplet #17

HL < 1 mm; first gastral tergum smooth and shiny => Carebara oni
HL > 1 mm; first gastral tergum punctate and microreticulate with longitudinal triations (Fig. 15A, B) => Carebara qianliyan

Liu, Z., Zhong, Y. et al. (2024), Figure 15. Head in full-face view and tergum in lateral view (C. qianliyan). A, HL > 1 mm first gastral tergum punctate with longitudinal striations.

19

return to couplet #17

Posterolateral corners of head with a pair of distinct horns or small tubercles (Fig. 16A, B) => 20
Head with no horns or tubercles (Fig. 16C) => 29

Liu, Z., Zhong, Y. et al. (2024), Figure 16. Horns or tubercles on the posterior corner of head. A, distinct horns. B, small tubercles. C, no horns or tubercles.

20

return to couplet #19

Propodeum with a pair of protruding denticles (Fig. 17A) => 21
Propodeum without a pair of protruding denticles; posterodorsal corner of propodeum rounded or forms an obtuse or right angle (Fig. 17B, C) => 23

Liu, Z., Zhong, Y. et al. (2024), Figure 17. Propodeum in lateral view. A, propodeum with protruding denticles. B, propodeum forming an obtuse angle. C, propodeum rounded.

21

return to couplet #20

Posterior area of head without transverse striations; metanotal groove impressed shallowly; body smaller with TL 1.4 mm (Fig. 18C) => Carebara acutispina
Posterior area of head with transverse striations; metanotal groove deeply impressed; body larger with TL 2.1–2.6 mm (Fig. 18A, B) => 22

Liu, Z., Zhong, Y. et al. (2024), Figure 18. Striations and metanotal groove. A, head with transverse striations. B, metanotal roove impressed deeply. C, metanotal groove impressed shallowly.

22

return to couplet #21

Mandible with 4 teeth on masticatory margin; clypeus with the anterior argin of median portion concave indistinctly => Carebara wheeleri
Mandible with 5 teeth on masticatory margin; clypeus with the anterior argin of median portion concave distinctly => Carebara obtusidenta

23

return to couplet #20

Horns connected by a developed transverse ridge (Fig. 19A) => 24
Horns not connected by a developed transverse ridge (Fig. 19B) => 25

Liu, Z., Zhong, Y. et al. (2024), Figure 19. Horns in dorsal view. A, horns connected by a transverse ridge. B, horns not connected by a transverse ridge.

24

return to couplet #23

Head capsule thin with straight anterior margin in lateral view (Fig. 20A) => Carebara bihornata
Head capsule thick with convex anterior margin in lateral view (Fig. 20B) => Carebara sakamotoi

Liu, Z., Zhong, Y. et al. (2024), Figure 20. Head capsule in lateral view. A, head capsule thin with anterior margin straight. B, head capsule thick with anterior margin convex.

25

return to couplet #23

Body larger with TL 3.0–3.5 mm => Carebara polyphemus
Body smaller with TL 1.5–2.3 mm => 26

26

return to couplet #25

Mandible with 4 teeth on masticatory margin => Carebara taiponica
Mandible with 5 teeth on masticatory margin => 27

27

return to couplet #26

Head coarsely microreticulate; frons and vertex with many striae (Fig. 21A) => Carebara yamatonis
Head largely smooth and shiny (Fig. 21B) => 28

Liu, Z., Zhong, Y. et al. (2024), Figure 21. Head in full-face view. A, head with dense microreticulation. B, head largely mooth and shiny.

28

return to couplet #27

Anterodorsal corner of propodeum prominent, forming an acute tooth behind metanotal groove (Fig. 22A) => Carebara sauteri
Anterodorsal corner of propodeum not forming an acute tooth (Fig. 22B) => Carebara rectidorsa

Liu, Z., Zhong, Y. et al. (2024), Figure 22. Mesosoma in lateral view. A, anterodorsal corner of propodeum forming an cute tooth. B, anterodorsal corner of propodeum not forming an acute tooth.

29

return to couplet #19

Head nearly square, ~ as long as broad; eyes with 16 facets; head with 3 ocelli; dorsum of mesosoma straight (Fig. 23A, B) => Carebara hunanensis
Head rectangular, longer than broad; eyes with < 10 facets; head without ocelli; dorsum of mesosoma not straight => 30

Liu, Z., Zhong, Y. et al. (2024), Figure 23. Carebara hunanensis. A, head with 3 ocelli in full-face view. B, dorsum of mesosoma traight in lateral view.

30

return to couplet #29

Propodeum with a pair of acute teeth; head with fine reticulations => Carebara reticapita
Propodeum forms an obtuse angle; head smooth, at most sparsely punctured => 31

31

return to couplet #30

Posterodorsal corner of propodeum forming a right angle of ~ 90° (Fig. 24A) => Carebara pseudolusciosa
Posterodorsal corner of propodeum forming an obtuse angle of more than 90° (Fig. 24B) => 32

Liu, Z., Zhong, Y. et al. (2024), Figure 24. Propodeum in lateral view. A, posterodorsal corner forming an right angle. B, posterodorsal corner forming an obtuse angle.

32

return to couplet #31

Vertex with transverse striations => Carebara jiangxiensis
Vertex smooth and with no striations => 33

33

return to couplet #32

Antenna 10-segmented; katepisternum rugose-reticulate; body distinctly larger with TL > 2.6 mm (Fig. 25A) => Carebara laeviceps
Antenna 9-segmented; katepisternum smooth and shiny; body smaller with TL ~ 2 mm (Fig. 25B) => Carebara lusciosa

Liu, Z., Zhong, Y. et al. (2024), Figure 25. Katepisternum in lateral view. A, katepisternum rugose-reticulate. B, katepisternum mooth.

References