Abstract
The morphology and morphogenesis of the hypotrichous soil ciliate Gonostomum kuehnelti Foissner, 1987, isolated from northwestern China, was investigated based on observations of live and protargol-stained specimens. Photomicrographs and some detailed morphological information, e.g. cortical granules and the number of dorsal kineties, are provided in this study. The morphogenesis of our population agrees in most details with that of the type population. The main events during binary fission are as follows: (1) the parental adoral zone of membranelles is retained completely; (2) six streaks of the undulating membranes and cirral anlagen are segmented in a 1: 2: 2: 2: 4: 4 pattern from left to right, and form three frontal, two frontoventral, one buccal, two frontoterminal, three postoral ventral, two pretransverse ventral, and two transverse cirri, respectively; and (3) the marginal rows and dorsal kineties develop intrakinetally. In addition, the SSU rDNA sequence of G. kuehnelti is provided. Phylogenetic analyses based on SSU rDNA sequences show that the genus Gonostomum is non-monophyletic and G. kuehnelti is placed within the core clade of Gonostomum.