Divisional Morphogenesis and Reorganization in Eschaneustyla brachytona Stokes, 1886 and Revision of the Bakuellinae (Ciliophora, Hypotrichida)

Abstract

Summary Divisional morphogenesis and physiological regeneration in Eschaneustyla brachytona Stokes, 1886 is described using protargol impregnation. The undulating membranes and the posterior anlagen of opisthe develop from the oral primordium, all other anlagen from disaggregated parental cirri. Usually all ventral anlagen generate more than two cirri, thus no typical midventral row composed of cirral pairs occurs. The parental proximal adorai membranelles are renewed and a frontoterminal (migratory) row develops. Reorganizes show that, in contrast to dividers, adorai membranelles are not only renewed in a higher number but three membranelles are additionally generated. Similarly, two more ventral anlagen on average are generated in reorganizers. Morphogenetic data show a close relationship of the genera Eschaneustyla, Bakuella Agamaliev and Alekperov, 1976, Keronella Wiackowski, 1985 and Holostichides Foissner, 1987. The four genera are united in the redefined subfamily Bakuellinae, Jankowski, 1979: Holostichidae with a midventral row composed of cirral pairs or several short oblique midventral rows in the anterior part and long midventral rows in the posterior part of ventral surface. Data from this investigation and from literature show that E. terricola Foissner, 1982 is a junior synonym of E. brachytona; likewise, the genus Parabakuella Song and Wilbert, 1988 is a junior synonym of Holostichides Foissner, 1978. Parabakuella typica Song and Wilbert, 1988 and Periholosticha wilberti Song, 1990 are transferred to the genus Holostichides. Definition of midventral and frontoterminal cirri is discussed.