Copromyxa – Microworld

Life cycle of Copromyxa protea based on Nesom (1973) and Spiegel and Olive (1978). Mature fruiting bodies (sorocarps) consist of a single cell type, sorocysts (A). Sorocysts germinate as amoebae (B). Trophic amoebae are limax shaped with a single nucleus (C). Amoebae may encyst to form microcysts, which can germinate as amoebae (D). Amoebae may form an aggregate, in which a founder cell of the sorocarp encysts and amoebae of the aggregate crawl on top of and encyst, to formsorocysts (E). Surrounding amoebae continue to crawl up the column of sorocysts and encyst at the apex (F–I). Trophic amoebae may come together (J). The two amoebae presumably undergo plasmogamy (K) then karyogamy, forming a thick walled sphaerocyst (L). The resultant life stage that follows sphaerocyst germination is unknown (?). The lighter shaded cells represent trophic amoebae and the darker cells are encysted (After Brown et al. 2011).

Genus Copromyxa Zopf, 1885 emend. Brown, Silberman and Spiegel 2011

Diagnosis: Amoebae in active locomotion typically monopodial in form with a well-pronounced hyaline cap and a round to tapering uroid. Uroid not differentiated, but often adhesive filaments form. Locomotive amoebae limax in form, but not eruptive; length/breadth ratio mean approximately 4. Normally a single vesicular nucleus with a single nucleolus. Cysts known to form in all species, smooth walled, spherical, ovoid, or irregular in shape. One species known to fruit via aggregation and differentiation of amoebae into columns or arborescent masses of irregularly shaped, walled sorocysts. A possible sexual cycle involving thick walled sphaerocysts reported for some strains of the fruiting species.

Type species: Copromyxa protea (Fayod, 1883) Zopf 1885

Ecology: Dung-inhabiting amoeboid

Literature:

Brown, WM, Silberman, JD, Spiegel, FW: “Slime Molds” among the Tubulinea (Amoebozoa): Molecular Systematics and Taxonomy of Copromyxa. Protist, Vol. 162, 277–287, 2011

Ferry Siemensma, created March 2, 2019; last modified February 02, 2021