Morphology and molecular phylogeny of Pleuronema orientale spec. nov. and Pleuronema paucisaetosum spec. nov. (Ciliophora, Scuticociliata) from Hangzhou Bay, China

Abstract

Two novel species, Pleuronema orientale spec. nov. and Pleuronema paucisaetosum spec. nov., isolated from coastal waters of Hangzhou Bay, China, were investigated with standard methods. Pleuronema orientale is characterized as follows: size in vivo 95–135 × 50–85 μm; usually one spherical macronucleus; 12–15 prolonged caudal cilia; two or three preoral kineties and 42–50 somatic kineties; membranelle 1 (M1) about 20 % of the anterior fragment of membranelle 2 (M2a) in length, consisting of three longitudinal rows of kinetosomes; posterior end of M2a hook-like; membranelle 3 (M3) three-rowed. Pleuronema paucisaetosum is characterized as follows: size in vivo about 55–85 × 25–55 μm; four or five preoral kineties and 21–23 somatic kineties; posterior end of M2a hook-like; M3 three-rowed. The small-subunit rRNA gene was sequenced for both species. Phylogenetic analyses revealed that P. orientale is most closely related to Pleuronema puytoraci and that P. paucisaetosum is sister to Pleuronema grolierei and Pleuronema setigerum (GenBank accession no. JX310015). With the inclusion of the two new sequences, the monophyly of the genus Pleuronema is not supported.