Acromyrmex ameliae

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Acromyrmex ameliae is a New World ant in the fungus‑growing group, found in Minas Gerais, Brazil. It is a social parasite that lives in the colonies of two host species, Acromyrmex subterraneus subterraneus and A. subterraneus brunneus.

The queen and other reproductives of A. ameliae are much smaller than those of the hosts. It can be told apart from its host by its straight, side‑to‑side compressed propodeal spines (the hosts have curved, cone‑like spines). It differs from the similar parasite Acromyrmex insinuator in color and in having no strong median rugosity around the central ocellus. The parasite workers resemble host workers, and the parasite queens resemble host queens mainly by size.

Nuptial flights of A. ameliae have been seen in the lab, and in the wild they are suspected. The parasite alates have been found in two seasons (April and October), while the host species have one yearly flight in November–December. This timing helps A. ameliae invade new host colonies before the hosts reproduce. In all studied colonies of A. subterraneus, A. ameliae was present.

A. ameliae appears to be quite common but has been overlooked until recently, hinting that other social parasites may exist. Like Acromyrmex insinuator, it relies on a worker force to produce parasite alates, a trait that is being reduced over time but not yet lost.