Morphology and molecular phylogeny of Euplotes baugilensis n. sp. (Ciliophora, Spirotrichea), with an illustrated key to Euplotes species with reduced cirri

Euplotes baugilensis n. sp. was discovered in a temporary puddle that formed after rainfall on a mountain footpath near Gangneung-Wonju National University in Gangneung, South Korea. After isolation, a pure culture was established, and the new species was examined using live observation, silver-impregnation (protargol and ‘wet’ silver nitrate), scanning electron microscopy, and the analysis of the 18S rRNA gene sequence. Morphologically, E. baugilensis n. sp. is characterized by small body size (on average 49 × 31 µm in vivo), 9 ordinary fronto-ventral cirri (cirrotype-9) with one reduced cirrus V/2 (composed of four non-ciliated basal bodies), 5 transverse cirri, 7 or 8 dorsolateral kineties, 6 dorsal prominent ridges, and a dargyrome (silverline system) of double type. In this study, we have used a combination of morphological and molecular techniques to characterize E. baugilensis n. sp. and determine its phylogenetic position within the genus Euplotes. Molecular analysis using 18S rRNA gene sequences indicated that E. baugilensis n. sp. is most closely related to E. curdsi (with a sequence identity of 96.8 %).