Dugesia gonocephalaとよばれてきた本邦淡水産プラナリアDugesia speciesの核型

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The Japanese triclad hitherto described as Dugesia gonocephala is one of the most common freshwater planarians in Japan. Marcus (1953) has summed up existing information on this triclad. On the basis of morphological data of the copulatory apparatus and pharynx he concluded that the gonocephala-like triclad existing in Japan is not identical with the European D. gonocephala. Furthermore, the Japanese Dugesia species exhibits certain physiological differences from the European species, D. gonocephala (Kato, 1943, 1950; Okugawa, 1953). The present authors studied the chromosomes of this species in question. The specimens were collected from four localities in Japan, Otaru (Hokkaido), Hirosaki (Honshu), Kyoto (Honshu), and Matsuyama (Shikoku). The chromosomes were investigated mitotic cells of neoblasts in regenerating pieces. Not visible differences were observed in the morphology of the chromosomes of specimens from the four localities under study. The chromosome number of this species was established as 2n=16. The karyotype consisted of 8 metacentric chromosomes in descending order of size. The centromeres are in all elements more or less medianly located, and individual chromosomes exhibit a gradual size-reduction. The chromosome labelled 1 is particularly large. The karyotype established by the present authors consistently agrees with the specimen from Matsumoto City, which was reported recently by Dahm (1963). In conclusion, the karyotype of the Japanese Dugesia species considered here differs from that of the European D. gonocephala presented by Dahm (1958, 1963) in which arms of chromosome labelled 3, 4 and 5 are not identical in length, whereas Japanese species the centromere is medianly located in each element.
1965-02-15

Dugesia gonocephalaとよばれてきた本邦淡水産プラナリアDugesia speciesの核型

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