Genus Willaertia De Jonckheere, Dive, Pussard & Vickerman, 1984
This genus was erected for a species with cysts containing pores like those in the cyst wall of Naegleria gruberi but, as then thought, no flagellate stage. Serological and isoenzyme analyses confirmed the distinctiveness of Willaertia. A short time later Michel & Raether erected the genus Protonaegleria for an organism with similar cysts but a quadriflagellate stage lacking a cytostome and not, as far as their observations showed, dividing in that stage. Subsequently, flagellates like those described for Protonaegleria westphali have been found in strains of Willaertia magna, including one of the original strains. Furthermore, the isoenzymes and restriction enzyme DNA patterns of P. westphali and W. magna are comparable. Therefore, though the original diagnosis of Protonaegleria was more complete with respect to the flagellate stage than was the original diagnosis of Willaertia, the latter name has priority because of its earlier publication date. There is, however, a possibility that the generic name Tetramastigamoeba Singh & Hanumaiah, 1977, is a senior synonym of Willaertia. Singh & Hanumaiah found ‘no obvious pores’ in the cysts of their organism but observed some pore-like structures. A new finding that W. magna divides in the flagellate as well as the amoeboid stage (B. Robinson and J. F. De Jonckheere, personal communication) increases the similarity. Flowever, until a strain of Tetramastigamoeba can be re-examined and biochemical comparisons with Willaertia made, it seems reasonable to recognise both genera. (Page, 1988)
Willaertia magna De Jonckheere, Dive, Pussard & Vickerman, 1984
Diagnosis: Amoebae up to 100 µm long (possibly with supernumerary nuclei), more often 50 µm or smaller, uroidal filaments prominent; strong tendency to supernumerary nuclei; usually a perinuclear layer of globules; nuclear diameter c. 4-7.5 µm; flagellates 19-30 um long (x 22 µm); cysts with distinct, thick inner wall layer, delicate outer layer loosely applied, spherical or polygonal depending on culture conditions, with plugged pores bounded by thickened rim, 18-28 µm (x 21-23 µm); specific isoenzyme pattern.
Ecology: Europe, Asia, Australia. NNE at 20-44°C; some strains adaptable to axenic culture (De Jonckheere et al., 1984).)
Remarks: In general, W. magna strongly resembles a large N. gruberi, from which W. magna differs in having a quadriflagellate rather than normally biflagellate stage and in undergoing division in the flagellate as well as the amoeboid stage. The pores of the cysts, with a thickened rim, are much like those of N. gruberi. There is also a perinuclear layer of globules, as in N. gruberi. W. magna can be grown at temperatures from normal room temperature to 44°C, but both sets of investigators found that it was not pathogenic to mice.