Morphogenesis and molecular phylogeny of a freshwater ciliate, Oxytricha multilineata n. sp. (Ciliophora, Hypotrichia)

Abstract

The morphology, morphogenesis, and molecular phylogeny of a new oxytrichid ciliate, Oxytricha multilineata n. sp. isolated from a tributary of the YuYao River, Ningbo, China, were investigated. Oxytricha multilineata n. sp. is characterized as follows: body size about 85–110 × 30–40 µm in vivo; 18 frontoventral-transverse cirri; paroral distinctly bipartite; seven dorsal kineties with cilia about 18 μm long; two macronuclear nodules and two micronuclei. The main events during morphogenesis follow a typical Oxytricha pattern with two exceptions: (1) only one anlage is formed initially within parental dorsal kineties 1–3, each of which then divides and is distributed into the two filial products, that is, the dorsal kineties anlagen are formed in primary mode; (2) dorsal kineties 3 and 4 are formed by incomplete fragmentation. Phylogenetic analyses based on SSU rDNA sequence data reveal that O. multilineata n. sp. clusters with Oxytricha lithofera, Heterourosomoida lanceolata and Quadristicha setigera, and species of the genus Oxytricha did not form a monophyletic group, however nodal support is not sufficiently high to recover a robust phylogeny of the Oxytrichidae.