The enigmatic protist Nephromyces.

This paper review current knowledge concerning the identity of Nephromyces, a collection of fungus-like cells found in the renal sac of all molgulid tunicates thus far examined. The following has been demonstrated: (1) The cells called Nephromyces do exist, and are not produced by their tunicate hosts, but are something foreign to these animals. (2) Many forms of "Nephromyces" cells are present simultaneously in the renal sac of adults of each molgulid species. Despite their extraordinarily eclectic appearance, all these cells are part of the same life cycle. (3) Initial ultrastructural data indicate that Nephromyces is a eukaryote. They also suggest that, despite the speculations of early authors, Nephromyces may not be a Chytridiomycete.