Pseudovahlkampfia
Pseudovahlkampfia Sawyer, 1980 (ref. ID; 3847 original paper)
[ref. ID; 3847]
Diagnosis; Small limax ameba with clear hyaline protoplasm forming thin cap along anterior margin of lobose eruptive pseudopods when in active locomotion; clear zone may flow or ripple along lateral margins in resting organisms; cannibalistic on agar plates; in areas where bacterial food is scarce form large multinucleate stages undergoing rapid plasmotomy when water is added; monopodial locomotive forms have pronounced posterior bulbous uroid with trailing filaments; resistant cysts not formed, but round pseudocysts may be present in liquid medium; nuclear division by promitosis with persistence of nuclear envelope throughout mitosis. (ref. ID; 3847)
Remarks; The genus is named to differentiate the ameba from the crabs from the closely related genus Vahlkampfia which does not contain species that form large plasmodium-like trophozoites. (ref. ID; 3847)
Type species; Pseudovahlkampfia emersoni sp. n. [by monotypy]. (ref. ID; 3847)
- Pseudovahlkampfia emersoni Sawyer, 1980 (ref. ID; 3847 original paper)
Diagnosis
Living amebae in aqueous medium average 25x8 (18-30x6-10) um; uninucleate or multinucleate, with nuclei ~6 um in diameter, with nucleoli ~4 um in diameter; amebae may form large, flattened, multinucleate stages on agar with a maximum diameter of 235 um and containing up to 50 um or more nuclei; multinucleate forms undergoing rapid plasmotomy upon addition of seawater, reverting to population made up entirely of uninuleate limax forms; nuclear division by promitosis; resistant cysts not formed; feeding on bacteria. (ref. ID; 3847)
Comments
Pseudovahlkampfia emersoni differs from the other members of the family by its large size in the multinucleate condition, its rapid plasmotomy upon the addition of seawater to agar plates, and its failure to form cysts. Living specimens of P. emersoni have 2 distinct growth patterns, depending upon the method of culture. In seawater alone, or on agar media overlaid with seawater, the organisms are typically monopodial or multilobed limax amebae and form thin-walled round pseudocysts which do not with stand dryness. On agar media not supplemented with a seawater overlay, small amebae are multinucleate, thin, flattened, irregular ovoid or large irregular forms that are cannibalistic. Pseudocysts are not formed on agar surface and amebae become dehydrated and lysed if not subcultured at frequent intervals. Clear hyaline protoplasm is usually reduced to a thin membrane-like layer which ripples, or flows posteriorly, or is completely absent because of shrinkage after fixation and staining. Mitotic nuclei are enclosed by a nuclear envelope throughout mitosis, and mitotic figures are as described for other species of the genus Vahlkampfia. (ref. ID; 3847)
Etymology
The species is named in honor of Dr. John Emerson of the National Marine Fisheries Service, U.S. Department of Commerce, Washington DC. (ref. ID; 3847)
Type host
Callinectes sapidus Rath. Quimby VA, USA. (ref. ID; 3847)
Location in type host
Digestive tract. (ref. ID; 3847)
Additional host
Ovalipes ocellatus (Herbst). Sandy Hook NJ, USA. (ref. ID; 3847)
Location on additional host
Gill surface. (ref. ID; 3847)