New data on Thecamoeba striata (Penard, 1890) (Amoebozoa, Discosea, Thecamoebida), and the geographical distribution of “T. striata species group”

Until recently, it was believed that amoebae of the genus Thecamoeba Fromentel, 1874 could be relatively easily distinguished from each other at the light-microscopic level. The main characteristics were the shape and size of the locomotive form and the morphology of the nucleus. However, recent studies with molecular methods have shown that several sibling species may be hidden behind every “classical” morphological species of Thecamoeba. Therefore, re-description and obtaining molecular data on “classic” Thecamoeba species became necessary tasks. However, during recent decades, almost all type cultures have been lost from international culture collections. During our study of the fauna of Moscow ponds, we isolated a strain identical to the type culture of T. striata established by F.C. Page both at the morphological level and by the sequence of the 18S rRNA gene. We obtained new images that clearly illustrated the diversity of locomotive forms and the morphology of the nucleus of the species T. striata. An analysis of faunistic studies showed that amoebae of “T. striata species group” are distributed almost worldwide and are a common component of freshwater and terrestrial ecosystems.