Department of Integrative Biology

A mermithid nematode (Nematoda: Mermithidae) from Lebanese amber represent the oldest definite fossil nematode. The specimen is assigned to a new species, H. libani sp. n. in the extant genus, Heleidomermis Rubstov. This specimen is still coiled inside the abdomen of its insect host, an adult biting midge (Diptera : Ceratopogonidae). This association represents the oldest known example of animal-animal internal parasitism in a terrestrial environment. The find demonstrates the antiquity of mermithid nematodes and establishes mermithid parasitism of the lower Diptera some 120-135 million years ago.