Tetramorium bonibony, Hita Garcia & Fisher, 2012

Garcia, Francisco Hita & Fisher, Brian L., 2012, The ant genus Tetramorium Mayr (Hymenoptera: Formicidae) in the Malagasy region — taxonomy of the T. bessonii, T. bonibony, T. dysalum, T. marginatum, T. tsingy, and T. weitzeckeri species groups, Zootaxa 3365, pp. 1-123 : 31-33

Tetramorium bonibony species group

Diagnosis

Eleven-segmented antennae; anterior clypeal margin medially impressed; frontal carinae usually moderately developed; anterior face of pronotum usually well-developed with distinct anterodorsal margin separating anterior face from dorsum, sometimes with anterodorsal margin shaped into a distinct protuberance; margination between lateral and dorsal mesosoma weakly to moderately developed; mesosoma comparatively high (LMI 40–51); propodeal spines medium-sized to long, elongate-triangular to spinose; propodeal lobes triangular and short; petiolar node in profile triangular, squamiform, or cuneiform, usually anteroposteriorly compressed dorsally, in profile much higher than long, in dorsal view typically distinctly wider than long and transverse, anterior and posterior faces generally not parallel, anterodorsal margin often better developed and higher situated than posterodorsal, dorsum then tapering backwards posteriorly; postpetiole approximately rounded; mandibles sculptured; cephalic sculpture distinct, between frontal carinae predominantly longitudinally rugose, posterior head and mesosoma with well-developed reticulate-rugose sculpture; petiole, postpetiole, and gaster usually unsculptured, smooth, and shiny, rarely weak sculpture present on waist segments; all dorsal surfaces of head, mesosoma, waist segments, and first gastral tergite with few to abundant standing hairs, never short, dense, and appressed; sting appendage spatulate.

Comments

The distribution of the T. bonibony species group is restricted to Madagascar, Nosy Be, and Nosy Mangabe, and the group members always live in forest habitats.

The development of the anterodorsal pronotum is comparatively variable among species in the group. It ranges from a weakly developed anterior face and anterodorsal margin (in T. kali ), through a well-developed anterior face and anterodorsal margin ( T. vony , T. sada , T. nosybe , and T. olana ), to a well-developed anterior face and a distinct anterodorsal median protuberance ( T. bonibony , T. popell , and T. trafo ). Despite being often unreliable and variable within some species, colouration seems to be quite useful as diagnostic character for the T. bonibony group. There is almost no variation in colouration within each of the species recognised here. Of the eight group members, one is dark brown, two are bicoloured (yellow and dark brown), and five are yellowish. We do not justify species delimitation based on colour alone, as we also provide morphological or ecological evidence in the species descriptions below. Still, colour is an easy means to distinguish the different members of this group.

The group is easily differentiable from all other 11-segmented species groups. The presence of a distinct protuberance on the pronotum distinguishes the three species T. bonibony , T. popell , and T. trafo directly from all other Malagasy Tetramorium . The remaining group members, except T. kali , cannot be confused with another group due the combination of a well-developed anterior pronotal face, reticulate-rugose sculpture on the posterior head and dorsal mesosoma, and triangular cuneiform petiolar node. Although T. kali lacks a well-developed anterior face and anterodorsal margin of the pronotum, it can be discriminated easily from the other groups. It possesses a unique character set of long propodeal spines, a cuneiform and unsculptured petiolar node, and distinct reticulate-rugose sculpture on posterior head and dorsal mesosoma.

Key to the species of the T. bonibony group (workers)

1. Mesosoma with distinct anterodorsal median protuberance on pronotum ( Fig. 29 )................................... 2

- Mesosoma usually with well-developed anterior face of pronotum, but always without distinct anterodorsal median protuberance on pronotum ( Figs. 30, 31 ).......................................................................... 4

2. Bicoloured species with brown to dark brown head and mesosoma and yellow to light brown waist segments and gaster; propodeal spines very long (PSLI 37–44) ( Fig. 32 )...................................................... T. bonibony

- Uniformly coloured species; propodeal spines medium-sized to long (PSLI 26–31) ( Fig. 33 ). ......................... 3

3. Petiolar node in profile distinctly triangular cuneiform and strongly anteroposteriorly compressed dorsally; in dorsal view highly transverse (LPeI 18–27; DPeI 400–590) ( Fig. 34 )................................................. T. popell

- Petiolar node in profile less strongly triangular, generally slightly cuneiform and only weakly anteroposteriorly compressed dorsally; in dorsal view less transverse than above (LPeI 48–54; DPeI 161–188) ( Fig. 35 )....................... T. trafo

4. Antennal scape comparatively longer (SI 76–82); anterior mesosoma without well-developed anterior face of pronotum ( Fig. 36 )............................................................................................. T. kali

- Antennal scape comparatively shorter (SI 65–73); anterior mesosoma with well-developed anterior face ( Fig. 37 ).......... 5 5. Bicoloured species with brown to dark brown head and mesosoma and yellowish to brownish waist segments and gaster ( Fig. 38 )............................................................................................ T. sada

- Uniformly coloured species ( Figs. 39, 40 )................................................................... 6 6. Body colouration brown to dark brown ( Fig. 41 )...................................................... T. nosybe

- Body colouration yellow to light brown ( Fig. 42 )............................................................. 7 7. Petiolar node cuneiform, in profile less anteroposteriorly compressed dorsally, in dorsal view less transverse (LPeL 45–50; DPeL 183–200) ( Fig. 43 )......................................................................... T. olana

- Petiolar node triangular cuneiform, in profile strongly anteroposteriorly compressed dorsally, in dorsal view highly transverse (LPeL 31–40; DPeL 245–333, generally around 300) ( Fig. 44 )............................................. T. vony

Figures

FIGURES 29–31. 29. Mesosoma of T. trafo in profile with distinct pronotal protuberance—CASENT0404115 (William Ericson 2011). 30. Mesosoma of T. sada in profile without distinct pronotal protuberance—CASENT0443274 (William Ericson 2011). 31. Mesosoma of T. kali in profile without distinct pronotal protuberance—CASENT0235221 (William Ericson 2011).

FIGURES 32 & 33. 32. Body of T. bonibony in profile with distinct bicolouration—CASENT0486252 (William Ericson 2011). 33. Body of T. trafo in profile with uniform colouration—CASENT0404115 (William Ericson 2011).

FIGURES 34 & 35. 34. Waist segments of T. popell in profile with strongly triangular petiolar node—CASENT0016867 (Estella Ortega 2012). 35. Waist segments of T. trafo in profile with less strongly triangular petiolar node—CASENT0404115 (William Ericson 2011).

FIGURES 36 & 37. 36. Mesosoma of T.kali in profile without well-developed anterior face of pronotum—CASENT0235221 (William Ericson 2011). 37. Mesosoma of T. sada in profile with well-developed anterior face of pronotum— CASENT0443274 (William Ericson 2011).

FIGURES 38–40. 38. Body of T. sada in profile with conspicuous bicolouration—CASENT0443274 (William Ericson 2011). 39. Body of T. nosybe in profile with uniform dark brown colouration—CASENT0422207 (William Ericson 2011). 40. Body of T. vony in profile with uniform yellow colouration—CASENT0404272 (William Ericson 2011).

FIGURES 41 & 42. 41. Body of T. nosybe in profile with uniform dark brown colouration—CASENT0422207 (William Ericson 2011). 42. Body of T. vony in profile with uniform yellow colouration—CASENT0404272 (William Ericson 2011).

FIGURES 43 & 44. 43. Waist segments of T. olana in dorsal view with significantly less transverse petiolar node— CASENT0044485 (William Ericson 2011). 44. Waist segments of T.vony in dorsal view with highly transverse petiolar node— CASENT0404272 (William Ericson 2011).