Su una popolazione della planaria Dugesia lugubris (biotipo E)

Benazzi, Mario

Atti della Accademia nazionale dei Lincei. Rendiconti della Classe di scienze fisiche, matematiche e naturali, Série 8, Tome 38 (1965) no. 6, pp. 787-790

Résumé

Seven chromosomal biotypes have been detected in the fresh-water planarian D. lugubris s. l. (Benazzi, 1957, 1960). Four of them (called A, B, C, D) can be arranged in an autopolyploid series, with biotype A (diploid 2 n = 8 , n = 4) being the lower member of the series. The other three biotypes (called E, F, G) have different chromosomes. The chromosomes of the biotype E (diploid 2 n = 8 , n = 4) differ for lenght, morphology and number of chiasmata from the chromosomes of the biotype A. The biotype F, with 2 n = 6, n = 3, probably has arised from biotype E by means of a centric fusion. Biotype G, also diploid (2 n = 8 , n = 4), has chromosomes which are different from both biotype A and biotypes E and F. The present communication deals with a new population of the biotype E, peculiar for the remarkable size of the specimens, some of which measure about 25 mm in lenght and 5 mm in width. They are all diploid. Biotypes E and F may be found in the same localities and the Author suggests that the two complements represent a case of chromosomal polymorphism.