Tetramorium ranarum species group

Based on Bolton and Hita Garcia and Fisher 2011.

An endemic Malagasy region species-group that holds some valid and many more (> 25) tentatively undescribed species.

This group is relatively unique within all groups with 11-segmented antennae since it displays a character set of comparatively small body size, shorter frontal carinae, often well-developed antennal scrobes, small propodeal spines, and especially a rectangular nodiform petiolar node. This character combination makes is fairly hard to be misidentified with another Malagasy species group. However, at first glance, it might be confused with some species of the T. tortuosum group due to the shared rectangular nodiform petiolar node shape, but the members of the T. tortuosum group are all much larger species with long frontal carinae and long to very long propodeal spines.

Diagnosis

Eleven-segmented antennae; anterior clypeal margin medially impressed; frontal carinae variably developed, ending about halfway between posterior eye margin and posterior head margin, often curving down ventrally and forming posterior margin, and sometimes even ventral margins, of antennal scrobes; anterior face of mesosoma only weakly developed; margination between lateral and dorsal mesosoma weak; propodeal spines short to medium-sized, triangular to elongate-triangular; propodeal lobes triangular and short; petiolar node rectangular nodiform with usually well-defined angles, in profile roughly as high as or weakly higher than long, in dorsal view typically as wide as long, often antero- and posterodorsal angles well-developed and about same height, sometimes anterodorsal angle better developed and higher situated than less angulate, more rounded posterodorsal angle, in the latter case dorsum usually tapering weakly backwards posteriorly; postpetiole usually roughly rounded; mandibles usually sculptured; cephalic sculpturation distinct and predominantly longitudinally rugose; mesosoma and waist segments with distinct sculpturation, postpetiole sometimes with weak sculpturation only; gaster almost always unsculptured, smooth, and shiny; dorsal surfaces of head, mesosoma, waist segments, and first gastral tergite generally with abundant, short to medium-sized, appressed to erect hairs, pilosity on first gastral tergite sometimes reduced; sting appendage spatulate.

References

Hita Garcia and Fisher. 2011. The ant genus Tetramorium Mayr (Hymenoptera: Formicidae) in the Malagasy region – introduction, definition of species groups, and revision of the T. bicarinatum, T. obesum, T. sericeiventre and T. tosii species groups. Zootaxa. 3039: 1-72.