Morphology and life cycle of amoeboflagellate Pharyngomonas sp. (Heterolobosea, Excavata) from hypersaline inland Razval Lake

Abstract

The morphology, life cycle, feeding and multiplication of amoeboflagellate Pharyngomonas sp., strain RL isolated from hypersaline inland Razval Lake was studied. Life cycle includes flagellate, amoeboid, and cyst stages. Flagellated cells have two anterior flagella and two posterior flagella emerging apically from the anterior end of the cell. The nucleus localizes closely to the base of flagella. The longitudinal groove is on the ventral side of the cell. Flagellated cells have a distinct cytopharynx in the anterior part of the ventral groove. The cytopharynx passes into an intracellular channel reaching the posterior end of the cell. Amoeboid cells have two morphotypes—heterolobosean and lobosean. Cysts are spherical, their wall is smooth. Cell division occurs either at flagellated stage or at amoeboid one. Distinctions of Pharyngomonas sp., strain RL, from Pharyngomonas kirbyi were determined. They include longer flagella and long filamentous branching pseudopodia at the posterior end of amoeboid cells. The morphological distinctions are in agreement with differences in structure of the 18S rRNA gene. The revealed features may be used for differentiation of Pharyngomonas species.