Tetramorium bonibony species group

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Based on Hita Garcia and Fisher 2012.

Key to Tetramorium bonibony-group species

Tetramorium species groups

Restricted to Madagascar, Nosy Be, and Nosy Mangabe. All the species live live in forest habitats.

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.

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.

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.

References

  • Hita Garcia and Fisher. 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: 1-123. PDF