First fossil record of nematode parasitism of ants; a 40 million year tale.

A mermithid nematode emerging from a male ant, Prenolepis henschei Mayr, in Baltic amber is the first fossil record demonstrating nematode parasitism of ants. This parasite, described as Heydeniusformicinus sp. n., is compared to extant mermithid parasites of ants, especially Allomermis myrmecophila Baylis 1921. The present fossil, together with earlier reports of braconid and mite parasitism of ants in Baltic amber, indicates that several diverse groups had already evolved parasitic associations with ants by the Eocene.