Rarest male ants

The rarest male ants are the males of a fungus-growing species known as Mycocepurus smithii, native to much of Latin America, but in particular Brazil, because no male specimen of this species has ever been discovered by scientists, either in field collections or in laboratory colonies. However, in certain colonies of this species queen ants have been found with sperm stored inside their reproductive tract, so males must occur in at least some colonies, but possibly only for short periods of time, or else they are extremely elusive as well as very rare.

Initially, this apparent absence of males, coupled with a genetic analysis of females sampled in a study conducted by University of Arizona researchers and published in 2009 – which revealed that they were all clones of their colonies' queens, and hence genetically identical to each other – seemed to suggest that this species only reproduced asexually.

In 2011, however, a new study of additional populations of this same species discovered that females in these colonies were genetically diverse, which is good evidence for ongoing sexual reproduction. Moreover, stored sperm was discovered inside the reproductive tracts of queen ants belonging to these colonies. Clearly, therefore, male ants must exist, but are evidently much rarer than females, and much more elusive too. Certain other ant species, including the infamous fire ants, are known to undergo asexual reproduction sometimes, but with plenty of males always existing.

It now appears that a mosaic of asexual and sexual populations, but with an apparent near-absence of males anywhere, occurs on a normal basis in M. smithii – a species formally described as long ago as 1893, but whose reproductive anomalies would remain unsuspected for another 116 years.