Abstract
Summary The morphology, infraciliature, and extrusomes of Remanella multinucleata (Kahl, 1933) nov. comb, were studied in live cells, in protargol impregnated specimens, and with the scanning electron microscope. The entire somatic and oral infraciliature consists of dikinetids which have both basal bodies ciliated or only the anterior or posterior ones, depending on the region of the cell. The right side is densely ciliated. Its most remarkable specialization is a kinety which extends on the dorsolateral margin from mid-body to the tail, where the kinetids become condensed and associated with conspicuous fibres originating from the ciliated anterior basal bodies. The left side seemingly has two ciliary rows extending along the cell margins. However, detailed analysis showed that these rows are very likely a single kinety curving around the cell. The oral infraciliature of Remanella is very similar to that of Loxodes spp., i.e. consists of four highly specialized and specifically arranged kineties, whose structure is described in detail. Previous investigations could not determine whether or how the nematocyst-like extrusomes of Remanella are extruded. The present study shows that they are discharged, thereby assuming a unique, drumstick-like shape because the roundish extrusome capsule remains attached to the despiralized filament. The data emphasize the close relationship between Remanella and Loxodes , earlier proposed by Kahl, and suggest that they emerged from a common ancestor which looked similar to a present day Loxodes . Remanella Kahl, 1933 is a nomen nudum because Kahl, when founding the genus with five new species and one new variety, failed to designate any as type. I thus reinstall Remanella nov. gen. for the species assigned to Kahl's invalid taxon and fix R. multinucleata as type species. Correct names, dates, and authorships are provided for all species described.
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