Among the odder ant-attacking parasites are mermithid worms. These nematodes sit coiled inside their hosts’ abdomens, consuming stored reserves and disrupting normal development. Infected ants have smaller heads and a distended gaster, a distortion striking enough that taxonomists failing to recognize the signs of parasitism have occasionally described these forms as novel species.
The online early edition of Myrmecological News carries a new report by Sándor Csosz where the author x-rays suspicious specimens in the genus Myrmica where parasitism may have duped early myrmecologists. Indeed, images of two purported “species” reveal the worms in all their glory.
I won’t be too quick to criticize other taxonomists’ mis-steps, however. I’ve made the same error myself. I once collected what I thought was a trimorphic Pheidole in Paraguay, giving them a temporary species number and their own tray in my collection, discovering only years later that the odd “intercaste” was actually parasitized majors of the common Pheidole flavens.
source: Csosz, S. 2012. Nematode infection as significant source of unjustified taxonomic descriptions in ants (Hymenoptera: Formicidae). Myrmecol. News 17: 27-31 Online Earlier.