Morphology and stomatogenesis of Pseudocohnilembus hargisi (Ciliophora: Scuticociliatida)

Abstract

The morphology and stomatogenesis of the marine scuticociliate Pseudocohnilembus hargisi collected from a shrimp culturing pond in Qingdao, China, were studied using pyridinated silver carbonate and Chatton–Lwoff silver impregnation techniques. The result shows that the Qingdao population of this species possesses typical characteristics of the genus Pseudocohnilembus: the buccal apparatus consists of three highly specialized membranelles; membranelle 1 comprises a single row of kinetosomes, is parallel to membranelle 2, and lies anterior to the paroral membrane; membranelle 2 is longer than membranelle 1 and also comprises one row of kinetosomes; membranelle 3 is located near the middle of the paroral membrane and comprises three rows of kinetosomes. The silverline system is similar to that of P. persalinus. During stomatogenesis, the parental scutica proliferates and becomes the primordial field. This subsequently develops in two separate parts, the anterior part eventually disappears while the posterior part forms membranelle 3 of the opisthe. The secondary proliferated field, which derives from the zigzag configuration of parental paroral membrane, also develops in two parts, with the anterior becoming the paroral membrane and scutica of the opisthe and the posterior part developing into membranelles 1 and 2 of the opisthe. The remnants of the parental paroral membrane give rise to the paroral membrane and scutica of the proter.