Abstract
The present paper deals with the chromosome numbers in the male complex of the following four species of fresh-water teleost fishes belonging to the Cyprinidae; Zacco temminkii (Temminck et Schlegel), Zacco platypus (Temminck et Schlegel), Pungtungia hilgendorfi (Ishikawa) and Phoxinus percnurus sachalinensis (Berg). The karyotypes of the former three species are very alike with each other and nearly identical in every respect of morphological characters. No numerical and morphological differences of chromosomes were found among these three species, as is clearly understood by reference to the accompanying figures (Figs. 1-6). The number of chromosomes was found to be uniformly 50 (2n) in the spermatogonial complex, of which at least two pairs are syntelomitic V-shape, while the remaining 23 pairs are orthotelomitic and simple rod-shape forming a well-graded series. From this evidence the supposition is possible that the haploid number is undoubtedly 25 in these species. In Phoxinus percnurus sachalinensis the condition is quite different. The haploid number observed in the primary and secondary spermatocytes was proved to be 27, the number being two more than that in the former three forms (Figs. 7-10). The diploid number is supposed, therefore, to be 54 in this species. The evidence obtained seems to show that the complement of this species contain at least four pairs of syntelomitic V-shaped chromosomes.
The following table shows the numerical relation of the chromosomes in the eypriniid fishes so far studied.
