Crematogaster

Crematogaster is an ecologically diverse genus of ants found worldwide, which are characterised by a distinctive heart-shaped gaster (abdomen), which gives one of their common names, Valentine Ant. Members of this genus are also known as Cocktail ants because of their habit of raising their abdomens when alarmed. It is the only genus of the tribus Crematogastrini. Most of species are arboreal. These ants are sometimes known as acrobat ants.

Read more about Crematogaster:  Species