Redescription of Atopospira galeata (Kahl, 1927) nov. comb. and A. violacea (Kahl, 1926) nov. comb. with redefinition of Atopospira Jankowski, 1964 nov. stat. and Brachonella Jankowski, 1964 (Ciliophora,Armophorida)

The taxonomy of the Metopidae (Ciliophora, Armophorida) remains poorly understood since most of its members have not been studied by modern morphologic and molecular methods. Recent molecular investigations have indicated that the two most species-rich genera, Metopus and Brachonella, are likely nonmonophyletic with at least one well-supported 18S rDNA clade comprised of a species from each of these genera (Brachonella galeata and Metopus violaceus). We investigated these two species with silver impregnation and scanning electron microscopy. Both taxa share important morphologic characteristics not described in other species of Metopus or Brachonella. These synapomorphies include: (1) a diplostichomonad paroral membrane, (2) a bipartite adoral zone with a short buccal part composed of ordinary membranelles and a longer distal part composed of much smaller membranelles bearing a single cilium or none and extending the same length as the perzonal ciliary stripe. We transfer Brachonella galeata (Kahl, 1927) Jankowski, 1964 and Metopus violaceus Kahl, 1926 to genus Atopospira Jankowski, 1964 nov. stat. Pending detailed morphologic and molecular characterization, Brachonella campanula, B. cydonia and B. pyriforma, B. intercedens, and B. lemani remain in Brachonella Jankowski 1964.     

Albert Wollenberger,Professor, Ph.D. (Harvard), Dr. Sc. Med. (Berlin)

Molecular and Cellular Biochemistry -     

Morphology and Morphogenesis of Metopus hasei Sondheim, 1929 and M. inversus (Jankowski, 1964) nov. comb. (Ciliophora, Metopida)

ABSTRACT The morphology and morphogenesis of Metopus hasei Sondheim, 1929 and M. inversus (Jankowski, 1964) n. comb, were investigated using live observation, silver impregnation, and scanning electron microscopy. Metopus has a spiral body organization and the ventral margin of the preoral dome bears five specialized ciliary rows, that form the so-called perizonal stripe. Division is homothetogenic, occurs in freely motile (i. e. non-encysted) condition, and includes a partial reorganization of the parental oral apparatus. During division, the complicated cell shape becomes ellipsoidal and all ciliary rows arrange meridionally. Stomatogenesis is entirely somatic (≅ pleurotelokinetal) and commences with the formation of kinetofragments in some dorsolateral kineties. The fragments become the opisthe's adoral membranelles, while the paroral membrane is generated by the left two perizonal ciliary rows, which proliferate kinetids intrakinetally. The perizonal stripe of the opisthe is generated by the three right parental perizonal kineties, which divide, and by two dorsolateral ciliary rows, which are added. The morphogenetic processes, especially the unique mode of formation of the paroral membrane, are used to define the order Metopida Jankowski, 1980 n. stat. more properly. The ontogenetic, ultrastructural, and sequence data available give no clear indication about metopid phylogeny, but definitely exclude metopids from the classical heterotrichs, with which they were classified for more than 100 years. Accordingly, we place the Metopida as incertae sedis in the subphylum Intramac-ronucleata Lynn, 1996.