New contributions to Gruberia lanceolata (Gruber, 1884) Kahl, 1932 based on analyses of multiple populations and genes (Ciliophora, Heterotrichea, Gruberiidae)

Gruberia Kahl, 1932 is a species-poor genus comprising only seven named species. Most of these species have not been reinvestigated since the original reports. In the present work, we investigated the taxonomy and phylogeny of Gruberia lanceolata (Gruber, 1884) Kahl, 1932 based on analyses of morphology and multiple gene sequences from four South Korean populations. This species is mainly characterized by a well-developed peristome region, segmented paroral membrane, and moniliform macronucleus. Some morphological features were not stable among the four populations investigated, such as body shape and size, cell color, and the ratio of oral length to body length. However, our molecular analyses of four different genetic markers - three nuclear DNA markers (18S rDNA, ITS1-5.8S-ITS2 region, D1D2 of 28S rDNA) and one mitochondrial (mt) marker (CO1 gene) - indicated that all Korean populations examined were the same species. Based on our present findings and historic works, we propose that G. calkinsi, G. aculeata, and G. beninensis are junior synonyms of G. lanceolata.