Unusual archamoeba Pelomyxa pilosa sp. nov. (Amoebozoa: Archamoebae: Pelobiontida): a light and electron microscopic study

Abstract

This paper presents the results of a study and describes a new species of pelobionts, Pelomyxa pilosa sp. nov. (Archamoebae: Pelobiontida). This species was found in the bottom sediments of a pond near St Petersburg (Russia) and was examined using light, immunofluorescence, and transmission electron microscopy. It is placed in the genus Pelomyxa Greeff, 1874 based on a combination of morphological features, including the mode of locomotion, the presence of numerous flagella, the organisation of the cytoplasm, and the presence of obligate prokaryotic endocytobionts. The new species can be easily distinguished from congeners by the specific presence of numerous prokaryotic ectobionts on the cell surface and the organisation of the nuclear apparatus. The nucleolar material in this species forms a hollow sphere consisting of tightly adjacent patches of various shapes and sizes, surrounded by granular material.