Description of Pelomyxa seravini sp. nov. (Amoebozoa: Archamoebae: Pelobiontida) and an identification key to the species of Pelomyxa

A new species of the genus Pelomyxa Greeff, 1874, P. seravini sp. nov., was isolated and described from the bottom sediments of freshwater bodies in north-western Russia. The morphology of P. seravini sp. nov. was examined using light microscopy, immunofluorescence microscopy, and transmission electron microscopy. Distinctive characters of the new species include a monopodial cell shape during locomotion, minimal cytoplasmic vacuolisation, the presence of three morphotypes of prokaryotic endocytobionts, and numerous lipid droplets within the cytoplasm. The main distinguishing characters of P. seravini sp. nov. relate to nuclear organisation: several peripheral intranuclear bodies and an association of the nuclear envelope with short microtubules. Based on morphological characters observable by light microscopy in representatives of the genus Pelomyxa, an identification key for currently known species is compiled.