Abstract
The morphology and molecular phylogeny of the new soil ciliate, Monomicrocaryon trimarginalis sp. nov., which was discovered in the soil of from Gwangdeok Mountain, Hwacheon-Gun, South Korea, were investigated. The new species is characterized by the following morphological features: cell ellipsoidal to slightly ovate, with both ends rounded; cortical granules absent; 17-24 adoral membranelles; three frontal cirri; four frontoventral cirri, two postoral ventral cirri; one buccal cirrus; 10-13 left and 9-13 right marginal cirri; five transverse cirri; four dorsal kineties and three dorsomarginal kineties; two macronuclear nodules and one micronucleus in between macronuclear nodules. Phylogenetic analyses showed that M. trimarginalis sp. nov. is placed within a clade containing M. euglenivorum euglenivorum and species belonging to Quadristicha in the dorsomarginalian hypotrichs.