Mayorella infected by the fungus Amoebophilus simplex
The photomicrograph above shows a Mayorella-species infected by a fungus, probably Amoebophilus simplex. This fungus is specialized in parasitizing mayorellid amoebae, maybe even exclusively Mayorella penardi. Unfortunately, infected amoebae are very rare. I have seen them occasionally and once abundant in a culture.
Infection by a fungus has been occasionally recorded on naked amoebae by several observers. Early researchers erroneously recorded conidia protruding from the posterior end of infected amoeba as uroidal filaments, and a new amoeba genus Ouramoeba Leidy, 1874 was established on this basis. Later, Penard (1902) correctly pointed out that these filaments are of parasitic origin. In spite of Penard’s opinion, Cash and Hopkinson (1905) recorded Leidy’s species Ouramoeba vorax Leidy, 1874 in British fresh water. Further records were identified correctly as fungal infections (Mrva, 2008).