Chromosome number variation in the genus Rubus in the Czech Republic. IV.

Chromosome numbers are given for a further 21 species of the genus Rubus including principally representatives of the subgenus Rubus (16 species) with, in addition, representatives of the subgenus Anoplobatus (2 species), the subgenera Idaeobatus and Cylactis and the nothosubgenus Idaeorubus (one species each). Four ploidy levels were found in this collection of plants originating from 57 localities in Bohemia and Moravia: three diploids (outside of the subgenus Rubus), four triploids, twelve tetraploids, and, in addition, two species displaying two ploidy levels each (tetra- and pentaploid R. guentheri, tri- and tetraploid R. ×pseudidaeus). First chromosome number reports are presented here for R. barrandienicus Holub et Palek (2n = 21), R. perrobustus Holub (2n = 21), R. indusiatus Focke (2n = 28), R. geminatus H. E. Weber (2n = 28), R. orthostachyoides H. E. Weber (2n = 28) and R. amphimalacus H. E. Weber (2n = 28). New cytotypes were found in an introduced R. allegheniensis Porter (2n = 28 here, 2n = 14, 21 in the literature) and in two native species: R. constrictus P. J. Mueller et Lefevre (2n = 28 here, 2n = 21 in the literature) and R. guentheri Weihe (2n = 35 found only rarely here, 2n = 28, 42 in the literature). The chromosome number of 2n = 28 given here for R. bertramii G. Braun is likely to be the first report concerning plants of known native origin. The chromosome numbers found in the remaining 11 species correspond to literature data. In this contribution three species studied karyologically represent new species for the flora of the Czech Republic: R. amphimalacus H. E. Weber, R. indusiatus Focke and R. orthostachyoides H. E. Weber. R. nessensis subsp. scissoides H. E. Weber is mentioned as a further new taxon for the Czech Republic. R. barrandienicus Holub et Palek is given as a new plant for Germany (Bavaria) and R. indusiatus Focke for Austria (Lower Austria). For all species studied, brief data on their chorology and ecology are given.