Key to the Indian and Sri Lankan Tetramorium tortuosum group species

Key to the workers of the Tetramorium tortuosum group species occurring in India and Sri Lanka, based on Akbar et al. (2023).

1

• Propodeum armed with a pair of short triangular spines which are only slightly longer than their basal width and only marginally longer than the propodeal lobes => Tetramorium urbanii

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  Akbar et al. (2023), Fig. 8. Tetramorium urbanii paratype worker (CASENT0901068 from www.antweb.org; photos by Estella Ortega). A, head in full-face view; B, body in lateral view; C, body in dorsal view.

• Propodeum armed with a pair of long spines which are much longer than their basal width and considerably longer than the propodeal lobes => 2

2

• Dorsum of postpetiole sculptured => 3
• Dorsum of postpetiole unsculptured, smooth and shining => 6

3

• Body pilosity abundant, very long (ca. 0.30 mm in length on the dorsal surface of the head and mesosoma), long erected hairs projecting from the extensor margin of the hind tibiae => 4
• Body pilosity sparser and much shorter (> ca. 0.15 mm in length), hind tibiae only with short pubescence => 5

4

• In profile view, petiolar node rounded, with a gradual transition between the anterior and dorsal faces, and the dorsal profile gently convex => Tetramorium pilosum

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  Akbar et al. (2023), Fig. 6. Tetramorium pilosum worker (CASENT0280881 from www.antweb.org; photos by Estella Ortega). A, head in full-face view; B, body in lateral view; C, body in dorsal view.

• In profile view, the anterior and dorsal faces of the petiolar node are almost perpendicular, forming a sharp angle, while the dorsal profile is roughly straight => Tetramorium yerburyi

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  Akbar et al. (2023), Fig. 9. Tetramorium yerburyi worker (CASENT0280880 from www.antweb.org; photos by Estella Ortega). A, head in full-face view; B, body in lateral view; C, body in dorsal view.

5

• Ferrugino-testaceous with gaster blackish brown, petiole minutely punctuate, dorsum with few faint reticulations, propodeal lobes are low and blunt => Tetramorium keralense

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  Sheela & Narendran (1998), Figs. 4-6. Tetramorium keralense worker. 4, body in lateral view; 5, head in full-face view; 6, antenna.

• Light brown with appendages yellow, petiole dorsum reticulate-rugose, propodeal lobes narrowly and acutely elongate => Tetramorium belgaense

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  Akbar et al. (2023), Fig. 3. Tetramorium belgaense worker (CASENT0280882 from www.antweb.org; photos by Estella Ortega). A, head in full-face view; B, body in lateral view; C, body in dorsal view.

6

• Comparatively smaller, dark black coloured species, clypeus without distinct median carinae => Tetramorium binghami

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  Akbar et al. (2023), Fig. 4. Tetramorium binghami worker. A, head in full-face view; B, body in lateral view; C, body in dorsal view.

• Comparatively larger, lighter ferruginous testaceous species with clypeus having a distinct median carinae => 7

7

• Propodeal lobes acute, pointed, anterior face of petiole forming blunt but distinct angle with petiolar dorsum => Tetramorium tortuosum

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  Akbar et al. (2023), Fig. 7. Tetramorium tortuosum worker (CASENT0280879 from www.antweb.org; photos by Estella Ortega). A, head in full-face view; B, body in lateral view; C, body in dorsal view.

• Propodeal lobes reduced, truncate to rounded not as pointed as above, petiolar node nodiform, anterior face and dorsum of petiole smoothly rounded not forming a blunt distinct angle as above => 8

8

• Mandible striate, propodeal spines with apex down curved and converging, dorsum of mesosoma strongly sculptured => Tetramorium hitagarciai

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  Akbar et al. (2023), Fig. 5. Tetramorium hitagarciai worker. A, head in full-face view; B, body in lateral view; C, body in dorsal view.

• Mandible mostly smooth, propodeal spines raised and diverging, mesosoma weakly sculptured => Tetramorium alii

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  Akbar et al. (2023), Fig. 2. Tetramorium alii worker. A, head in full-face view; B, body in lateral view; C, body in dorsal view.

References

• Akbar, S. A., Schifani, E., Bharti, H., Wachkoo, A. A. 2023. Taxonomic overview of the Tetramorium tortuosum group (Hymenoptera, Formicidae) in India and Sri Lanka, with descriptions of three new species from the Western Ghats biodiversity hotspot. Annales Zoologici Fennici 60:109-126. (doi:10.5735/086.060.0112).