Morphogenesis and molecular phylogeny of two soil ciliates Australocirrus australis (Foissner, 1995) Kumar and Foissner, 2015 and A. aspoecki (Foissner, 2004) Kumar and Foissner, 2015 (Ciliophora, Hypotrichia).

The morphogenesis and molecular phylogeny of two soil hypotrich ciliates, Australocirrus australis and A. aspoecki, collected from Xi’an, Shaanxi Province, China, were investigated using protargol preparation. The main features of morphogenesis of A. australis are as follows: (1) the parental adoral zone of membranelles is retained completely in the proter; (2) parental cirri and the undulating membranes are involved in the formation of six primordial streaks; (3) multiple fragmentation of the third dorsal kinety anlage; (4) more than three dorsomarginal kineties are formed. An early divider of A. aspoecki was also found, and its morphogenetic events resemble those of other Australocirrus species. Furthermore, the SSU rDNA sequence of the Shaanxi populations of A. australis and A. aspoecki was provided. The molecular phylogeny indicates that A. aspoecki clusters together with A. rubrus and two populations of A. australis with full support, which are separated from the clade comprising the two populations of A. shii.