Ref ID : 7751
Helmut Berger, Wilhelm Foissner and Hans Adam; Morphological Variation and Comparative Analysis of Morphogenesis in Parakahliella macrostoma (Foissner, 1982) Nov. Gen. and Histriculus muscorum (Kahl, 1932), (Ciliophora, Hypotrichida). Protistologica XXI(3):295-311, 1985
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A comparative analysis of the morphology and the morphogenesis of the kahliellid Parakahliella macrostoma nov. comb. and the oxtrichid Histriculus muscorum was performed. The morphogenesis of P. macrostoma reveals the following peculiarities: a) The primordium III originates from the third anteriormost cirrus of the short frontal row, suggesting a homology with the cirrus III/2 of the oxytrichids. b) The cirri of the primordium IV migrate in a posteriad direction, forming the left fronto-ventral row of non-dividers. The conformities in pattern formation imply a rather close lineage of the Kahliellidae and Oxytrichidae. c) Each two right and left somatic ("marginal") cirral rows are developed and fragments of the parental dorsal kineties 4 and 5 are conserved as "new kinety 4". The homonomy of the dorsal kineties and marginal rows is proposed. Morphogenesis of H. muscorum is similar to that of Stylonychia and Oxytricha. The phenetic resemblance of 4 alpine populations of H. muscorum is assessed on the basis of 29 characters, by means of both a multiple comparison procedure and the coefficient of racial likeness. Both methods give a good reflection of the geographical distances of their sample sites. However, at present it is impossible to decide if the differences observed are due only to effects of the environment upon the phenotype or if they are determined genetically. The analysis of correlation yields only a few significant associations, suggesting a rather great taxonomic value of the selected characters. A comparative consideration of the morphogenetic processes in some species formerly assigned to Kahliella and Paraurostyla suggests the establishment of two new khaliellid genera. Parakahliella nov. gen. is characterized by the presence of caudal cirri and more than one right and one left selfreplicating somatic ("marginal") rows. Because of the conspicuous resemblance of Parakahliella macrostoma and Paraurostyla terricola the later species is also transferred into the new genus: Parakahliella terricola (Buitkamp, 1977) nov. comb. The evolved frontal ciliature and the high dominance of the somatic cortical pattern in Kahliella marina Foissner et al.,1982 justify the establishment of a further, presumably ancestral kahliellid genus, Pseudokahliella nov. gen. The first character separates it from Parastrongylidium and the second from the other related genera.