Tetramorium grassii species group

AntWiki: The Ants --- Online

Based on Bolton 1980

Species

Identification

Diagnosis

Antennae with 12 segments. Sting appendage conspicuously spatulate. Anterior clypeal margin notched or impressed (faint or absent in rugulare). Frontal carinae strong, running back almost to occiput and surmounted by a rim or flange which is strong at least to the level of the posterior margins of the eyes. Antennal scrobes present. Petiole in profile a high, narrow node, much higher than long, not squamiform but narrow in posterior view. In dorsal view the petiole node somewhat broader than long. Petiole, postpetiole and gaster unsculptured. Pilosity dense on dorsal surfaces of head and body but the scapes and tibiae only with short subdecumbent to appressed pubescence.

Notes

This small group of five closely related species is restricted to southern Africa, most species being found only in South Africa itself. One species (Tetramorium grassii) has been introduced in New Zealand (Brown, 1958). The grassii-group is possibly ancestral to the weitzeckeri- and squaminode-groups and is also closely related to the schaufussi-group of the Malagasy region. Tetramorium grassii is the most widespread and also the most variable member of the group, being widely distributed in South Africa and also occurring in Swaziland. The other four species are each known from only one or two localities, mostly in South Africa, but at present Tetramorium plumosum has only been found in Swaziland. Among the five species two (Tetramorium titus and Tetramorium vexator) form a close species-pair in which the mandibles are smooth, the propodeal spines short and the petiole node narrowed dorsally. In the remainder (T. grassii, T. plumosum, Tetramorium regulare) the mandibles are striate, the propodeal spines relatively long and the petiole not narrowed above. Of these three T. plumosum is very distinct as it is one of the few African Tetramorium species to show bizarre pilosity, in this case plumose apically. The final two are separated on details of structure and sculpture as noted in the key and in the discussions under the species.

Additional Resources

References