The nematode tapeworm: rediscovery of the bizarre parasite of nematodes, Spirogyromyces vermicola Tzean & Barron (Fungi, incertae sedis) in northeastern Mexico

We report the second world observation of the bizarre nematode-parasitic fungus-like organism, Spirogyromyces vermicola, from forest soil at Saltillo, Mexico. It is a benign parasite of nematodes that fills their intestine. Its phylogenetic position remains a mystery, but its morphology and development are reminiscent of Harpellales and Orphellales in the Kickxellomycotina. Spirogyromyces was cultivated in vivo in the original host (Rhabditis) and in Caenorhabditis elegans. Spirogyromyces proliferated in both hosts, and it did not appear to affect significantly health, reproduction, or numbers of hosts. The rediscovery of Spirogyromyces will highlight its potential in the study of parasitic systems in nematodes, including Caenorhabditis research.