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.

Morphologic and molecular description of Metopus fuscus Kahl from North America and new rDNA sequences from seven metopids (Armophorea, Metopidae)

“…Due to the paucity of material, we could not document the details of morphogenesis. Foissner and Agatha (1999) also noted the rarity of M.…”

“…Terminology is according to Foissner and Agatha (1999), Jankowski (1964b), Lynn (2008 and Rosati and Modeo (2003). We define the ventral side of the cell as that surface on which the terminus of the adoral zone (and the cytostome) is at the right margin.…”

“…One of the "reliable" species ("because of observed conjugation") was M. fuscus. In a subsequent rebuttal, Kahl (1929) (Dragesco 1968(Dragesco , 1996Esteban et al 1995;Foissner and Agatha 1999;Jankowski 1964aJankowski , 1964bJankowski , 2007. (1995), although not citing Wetzel (1928), shared his view that the genus Metopus was rife with synonymous species.…”

“…A meaningful revision of the metopids remains a distant but important goal that will require detailed descriptions of as many of the nominal species as possible (Dragesco 1996;Foissner and Agatha 1999). Because modern descriptions for most Metopus and other armophorid genera (e.g.…”

Large-scale phylogenomic analysis reveals the phylogenetic position of the problematic taxon Protocruzia and unravels the deep phylogenetic affinities of the ciliate lineages

“…However, the support for this relationship has never been strong (Embley and Finlay, 1994;Gong et al, 2009;Hammerschmidt et al, 1996;Hirt et al, 1995;Vd'ačný et al, 2010). Nevertheless, the two classes do share some ontogenetic features (Foissner and Agatha, 1999). Based on these findings, Vd'ačný et al (2010) proposed that Litostomatea and Armophorea be united into the Lamellicorticata.…”