Morphology and phylogeny of two new pleurostomatid ciliates, Epiphyllum shenzhenense n. sp. and Loxophyllum spirellum n. sp. (Protozoa, Ciliophora) from a mangrove wetland, South China.

The morphology, infraciliature, and small subunit (SSU) rRNA gene sequences of two new pleurostomatid ciliates, Epiphyllum shenzhenense n. sp. and Loxophyllum spirellum n. sp., isolated from a mangrove wetland near Shenzhen, South China, were investigated. Epiphyllum shenzhenense n. sp. is morphologically characterized by leaf-shaped cell about 150 x 35 microm in vivo, usually with four contractile vacuoles, 20-29 right kineties and 10-26 left kineties, ca. four macronuclear nodules, and two types of extrusomes (i.e. short spindle-shaped and long bar-shaped). As a new species, L. spirellum n. sp. is distinguished from its congeners by its posterior dorsal margin twisted onto the left side, the distribution of extrusomes (evenly arranged along the oral slit, the posterior end, and clustered to 7-13 warts on dorsal margin), the subterminally positioned contractile vacuole, the number of kineties (8-10 on right side, 4-5 on left side), and its genetic distance from congeners. Phylogenetic trees based on the SSU rRNA gene sequence for both organisms were constructed, which indicate that Epiphyllum is a distinct genus and occupies a basal position in the Pleurostomatida clade; L. spirellum n. sp. falls well into the Loxophyllum clade, which has a close relationship with Litonotus and Spiroloxophyllum.