Ref ID : 7737
Birthe Zimmermann, Qjvind Moestrup, and Guy Hallfors; Chrysophyte or Heliozoon: Ultrastructural Studies on a Cultured Species of Pseudopedinella (Pedinellales Ord. Nov.), with Comments on Species Taxonomy. Protistologica XX(4):591-612, 1984
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Five strains of Pseudopedinella elastica from the south coast of Finland were studied by light microscopy, one of them also by electron microscopy. Observations reported include description of the morphology and its variation, and of the swimming behaviour. The fine structure is described with special emphasis on the flagellar apparatus, tentacle-associated microtubules, and a complex posterior vacuolar system in an intermediate position between the Golgi apparatus and a long contractile trailing stalk. Tentacles were found in the posterior end probably in association with the vacuolar system, while the anterior end had only vestigial tentacles. The problem of the species concept in the genus Pseudopedinella is discussed, and it is suggested that several of the described species should be merged. The new order Pedinellales is formally proposed, to encompass the photosynthetic genera Pedinella, Pseudopedinella and Apedinella with normally 3 or 6 chloroplasts, and the non-photosynthetic genera Actinomonas, Ciliophrys and Pteridomonas. The members are characterized by radially symmetrical cells, one external anterior flagellum carrying tripartite hairs and a wing usually supported by a paraxial rod. Triads of microtubules associated at one end with the nuclear envelope, while at the other they terminate at the cell membrane or support tentacle (axopods). The genera Cyrtophora and Palatinella, usually treated in the same context as Pedinella, but with only one lobed chloroplast, are too poorly known to be safely included in Pedinellales.