Representatives of the genus Cochliopodium Hertwig & Lesser, 1874 (Amoebozoa; Discosea) in the natural biotopes of Ukraine

Amoebae species of the genus Cochliopodium are widespread in aquatic habitats and soils and exhibit limited morphological differentiation. Thus, the number of described species remains low. They are difficult to maintain in culture due to their nutritional and reproductive peculiarities. Today, accurate species identification requires modern light microscopy and DNA sequencing. GenBank contains a small number of 18S rRNA gene sequences of Cochliopodium. The aim of our study was to isolate species of naked amoebae from water bodies in Ukraine, identify them by morphological characteristics and 18S rRNA genome, and determine their phylogenetic position within Amoebozoa. From the waters of Ukraine, we identified the marine species Cochliopodium gulosum and the freshwater species Cochliopodium actinophorum (MZ079367), Cochliopodium minus (OK649264), and Cochliopodium sp. (MZ079368). They share morphological characteristics such as the locomotor form, the presence of extracellular integumentary structures of the tectum type, and a vesicular nucleus. In our analysis, naked amoebae belonging to the molecular clusters Tubulinea and Discosea form a clade within Amoebozoa. Within Tubulinea we recover species from the order Euamoebida, while within Discosea we recover Dactylopodida, Vannellida, Thecamoebida, Dermamoebida, Acanthamoebida, and Himatismenida. Representatives of the genera Cochliopodium and Gocevia are grouped in Himatismenida. One group is formed by sequences of the species Cochliopodium minus (OK649264, JQ271675, JQ271674), another group contains Cochliopodium actinophorum and Cochliopodium sp. (MZ079367, JF298250, MZ079368), and the third group, Cochliopodium kieliense and Cochliopodium larifeili (KJ569725, KJ569727, JF298253).