Morphology and Molecular Phylogeny of Two New Brackish Water Ciliates of Bakuella (Ciliophora: Urostylida: Bakuellidae) from South Korea

Abstract

Two new species of Bakuella, B. (B.) incheonensis n. sp. and B. (Pseudobakuella) litoralis n. sp., were discovered in brackish water near Aamdo Shore Park, Incheon, South Korea. We conducted a morphological study based on live observations and protargol-impregnated specimens, and a molecular analysis using nuclear SSU rRNA gene sequences. Bakuella (B.) incheonensis is diagnosed by: body size 70-105 × 20-40 μm in vivo, 21-25 adoral membranelles, three or four frontoterminal cirri, midventral complex composed of 7-10 midventral pairs with one or two rows and terminating at about 62% of body length, 20-28 left and 25-32 right marginal cirri, 58-87 macronuclear nodules, and yellowish cortical granules. Bakuella (Pseudobakuella) litoralis is diagnosed by: body size 90-125 × 30-40 μm in vivo, 25-33 adoral membranelles, 3-5 buccal cirri, midventral complex composed 10-15 midventral pairs with one or two rows and terminated at 70% of body length, one or two pretransverse cirri, 3-6 transverse cirri, 26-39 left and 29-47 right marginal cirri, 49-84 macronuclear nodules, and two types of cortical granules. Molecular phylogeny using SSU rRNA gene sequences shows a nonmonophyletic relationship among Bakuella species and emphasizes the need for further morphogenetic studies of this genus and other related hypotrichs.

Keywords: Bakuella incheonensis; Bakuella litoralis; SSU rRNA gene; ciliature; new species.