Morphology, morphogenesis, and molecular phylogeny of a new freshwater ciliate, Gonostomum jangbogoensis n. sp. (Ciliophora, Hypotricha), from Victoria Land, Antarctica

In a study on ciliate diversity, we discovered the new hypotrich species, Gonostomum jangbogoensis n. sp., in freshwater from Terra Nova Bay, Victoria Land, southeast Antarctica. We describe its morphology and morphogenesis using standard methods, and the SSU rRNA gene phylogeny is provided as well. Morphology of Gonostomum jangbogoensis n. sp. is characterized as follows: slender to elongated body shape; grayish under low magnification; cortical granules present; 32 - 1 adoral membranelles; 3 enlarged frontal cirri; 1 buccal cirrus; 2 frontoterminal cirri; 3 or 4 frontovemral cirral pairs, 2 pretransverse cirri, 6-7 transverse cirri; 13-19 left and 18-26 right marginal cirri; 17-23 paroral kinetids; 3 dorsal kinetics; 3 caudal cirri; 2 macronuclear nodules with 1-3 micronuclei. The morphogenesis of the new species confirms that it has at least seven frontal-ventral-transverse cirral anlagen, which is also reported in Gonostomum sp. 1 sensu Shin from Korea. Even though these two populations occur very far from each other, the morphometric data prove that this character state, the seven cirral anlagen, is a stable feature across these populations and might be an apomorphy. The phylogenetic analyses show that the genus Gonostonvini is non-monophyletic and that the new species is a sister to G. bromelicola. (C) 2020 Elsevier GmbH. All rights reserved.