The Morphology of Three Loxophyllum Species (Ciliophora, Pleurostomatida) from Southern China, L. lembum sp. n., L. vesiculosum sp. n. and L. perihoplophorum Buddenbrock, 1920, with Notes on the Molecular Phylogeny of Loxophyllum

Abstract

Two new pleurostomatid ciliates, Loxophyllum lembum sp. n., L. vesiculosum sp. n., and the poorly known L. perihoplophorum Buddenbrock, 1920, isolated from brackish waters in coastal regions of southern China, are described following observations of live cells and protargol-impregnated specimens. Loxophyllum lembum sp. n. is distinguished by a combination of characters including two macronuclear nodules, 6-9 contractile vacuoles along the ventral margin, 11-14 right and 6-8 left kineties and the presence of cortical granules. Loxophyllum vesiculosum sp. n. differs from its congeners mainly by the unique distribution of contractile vacuoles, several of which lie along the dorsal margin and one on the ventral margin, and 15-21 right and 6-8 left kineties. Loxophyllum perihoplophorum is characterized by its large cell size (350-450 μm long in vivo), 3-5 contractile vacuoles along the dorsal margin in the posterior region of the body, and 19-23 right and 7-9 left kineties. An improved diagnosis of L. perihoplophorum is provided. The SSU rDNA sequence of L. perihoplophorum is reported for the first time and its molecular phylogeny is analyzed. Maximum likelihood and Bayesian inference analyses of SSU rDNA sequence data recover the monophyly both of the order Pleurostomatida and of the genus Loxophyllum.