Redescription of Rigidohymena inquieta (Stokes, 1887) Berger, 2011 as Metahymena inquieta gen. nov., comb. nov. (Ciliophora, Hypotricha) Based on Morphology, Morphogenesis, and Molecular Phylogeny.

The morphology and morphogenesis of Rigidohymena inquieta (Stokes, 1887) Berger, 2011, isolated from a lawn soil in the campus of the University of Ulsan, Korea, was studied, using live observation and protargol impregnation. The molecular phylogeny was studied based on the SSU rRNA gene sequences. The morphology of the Korean population of R. inquieta matches the previously known populations; however, the morphogenetic pattern shows differences to the species R. candens in the involvement of cirrus V/3 in the anlagen formation. A novel genus namely Metahymena gen. nov. has been erected for the present species based on the ontogenetic difference, and the new combination Metahymena inquieta gen. nov., comb. nov. is proposed. The morphology, morphogenesis, distribution, and phylogeny of M. inquieta are presented. The morphologic and morphogenetic data corroborate the phylogenetic analyses as M. inquieta clusters among the stylonychid ciliates in a clade distant from Rigidohymena candens.

Morphology, Morphogenesis, and Phylogeny of Urosoma caudata (Ehrenberg, 1833) Berger, 1999 (Ciliophora, Hypotrichia) based on a Chinese Population.

We report the morphology and morphogenesis of Urosoma caudata (Ehrenberg, 1833) Berger, 1999 based on in vivo observation and protargol impregnation and provide an improved diagnosis of U. caudata based on previous and current work. Urosoma caudata differs from its congeners mainly by the combination of the following features: tail-like posterior end, colorless cortical granules, and two macronuclear nodules. Urosoma caudata shares most of the ontogenetic features with its congeners: the oral primordium of the opisthe develops apokinetally, and the frontal-ventral-transverse cirral anlagen develop in five streaks. However, a unique morphogenetic characteristic is recognizable: the anlagen of three dorsal kineties occur de novo to the left of the parental structures differing from their intrakinetal origin in other Urosoma species. The first record of the 18S rRNA gene sequence for the species is also provided. Phylogenetic analyses based on 18S rRNA gene sequence data suggest that the genus Urosoma is a nonmonophyletic group.

Hypotrichous ciliates (Protozoa: Ciliophora) from a temporary pond in Argentina, with redescription of Apoamphisiella hymenophora (Stokes, 1886) Berger, 1999.

Hypotrichous ciliates collected in the plankton and soil samples from a temporary pond in Buenos Aires province, Argentina, were characterized after live observations and protargol impregnation. Apoamphisiella hymenophora (Stokes) Berger is redescribed and the neotype material deposited. Apoamphisiella hymenophora differs from its congeners in having 2 macronuclear nodules, 1 contractile vacuole with anterior and posterior collecting canals, the absence of cortical granules, 2 cirri behind the rightmost frontal cirrus, 1 postoral cirrus, 6 dorsal rows of dikinetids along with scattered dikinetids on the right body margin, and 3-9 caudal cirri arranged in groups at the ends of dorsal rows 1, 2, and 4. Rigidohymena candens, R. quadrinucleata, Histriculus histrio, Gastrostyla steinii, and Pseudouroleptus caudatus are new for the Argentine microfauna. Since especially the soil ciliates have been almost unexplored in South America, the results from the present investigation describe and contribute to the knowledge of the diversity of these microorganisms within this geographical region.