Stomatogenesis and morphological re-description of the marine ciliate,Philasterides armatalis(Protozoa: Ciliophora: Scuticociliatida)

Abstract

The stomatogenesis and morphology of the marine planktonic ciliatePhilasterides armataliscollected from mollusc-culturing waters off the coast of Qingdao, China, were studied using a differential interference contrast microscope for observationsin vivoand protargol impregnation. In terms of its infraciliature, this species possesses typical characteristics of the genusPhilasterides: bipartite paroral membrane, the anterior part double-rowed and the posterior part in a zig-zag-formation, and three well-defined membranelles arranged inParanophrys-pattern. This investigation confirms the dual origin of the buccal apparatus in the opisthe, one derived from the scutica and the other from the paroral membrane. Its stomatogenesis belongs to the ‘Philasterides’ sub-type, although it differs from its only congenerP. armata, in that paroral membrane 1 gives rise to the paroral membrane and the scutica in the proter, and paroral membrane 2 forms the paroral membrane, membranelles 1 and 2 and the scutica in the opisthe. Based on stomatogenetic data, the phylogenetic positions of several genera in the suborder Philasterina are reconsidered.