Most ant species have only two castes: reproductives and workers. Reproductives help to sustain the colony by laying eggs, while workers forage for food, care for the young, and defend the colony.
However, the workers of some ants are solely responsible for defense, and they are often considered to be a subcaste known as soldiers. Soldier ants are usually larger and more muscular than the workers, and they often have specialized mandibles or other body parts to help them fight.
One group known as “door head” ants have soldiers whose heads are shaped like saucers, or concave shields, which they cover with camouflaging layers of debris. They use these peculiar features to block the entrances of their nests against intruders, such as other predatory ants or invertebrates. While the shape of their heads allows them to perfectly fit into the nest entrance, they also have special armor that shields their vulnerable eyes, antennae, and mouthparts.
Ants with these door head features are known as phragmotic ants. Recently, two new species were retrieved from sifted leaf-litter collected in rainforests in Western Kenya and the Ivory Coast. Both species are described in the journal ZooKeys.
Previously, some phragmotic and non-phragmotic ants from this area were thought to be two different species in the genus Carebara. However, by using morphological and next-generation sequencing analysis, the researchers have shown that they are actually the same species. In addition, they also found another species in the same genus.
The new species have been given the names Carebara phragmotica and Carebara lilith. The former is derived from the term phragmosis, in relation to the special function of their head shape, while the latter comes from the name of a female demon in Jewish mythology.
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