Genetic differentiation of the two hybrid diploid-polyploid complexes of loaches, genus Cobitis (Cobitidae) involving C-taenia, C-elongatoides and C.spp. in the Czech Republic: Karyotypes and cytogenetic diversity

The karyotype and cytogenetic diversity of the spined roaches of the genus Cobitis in the Czech Republic was surveyed using convetionl Giemsa-staining , Ag-staining, C-banding, CMA3-fluorescence and florescence in situ hybridi zation (F.I.S.H.) with 28S DNA probe. C. elongatoides Bacescu et Maier, 196 9 was identified as a diploid leach species inhabiting both Elbe and Danube basins of the Czech Republic. This species has 2n = 50 and a karyotype com posed of 15 pairs of meta- (m), 8 pairs of submeta-(sm), 1 pairs of subtelo - (st) and 1 pair of acrocentric (a) chromosomes. The complex specific NOR- phenotype,included one medium m, one small and large sm pair. The structura l polymorphism of the presence and/or absence type regarding the ribosomal sites was observed with the number of NORs ranging from one to four. In the middle Elbe R. basin, the hybrid diploid/polyploid complex of this species occurred with C. taenia sensu Va s i l e v & Va s i l e v a (1994). This s pecies has 2n = 48 and a karyotype identical to that described by V a s i l j e v ' s team from Moscow region. The NOR-bearing chromosome pairs includ e one medium sized sm pair with NORs covering entire short arms. The identi cal karyotype found in the individuals from Weser R. basin (northwestern Ge rmany), Kleiner Ploner See (northern Germany) and Klawoj Lake (norteastern Poland) confirmed such a conclusion. In the middle Danube basin, triploid a nd tetraploid individuals occur. Besides the diploid karyotype of C. elonga toides, the karyotypes of triploid individuals also contained a haploid chr omosome set with 8 m, 13 sm and 4 st - a chromosomes, while in tetraploid i ndividuals to those two previous ones, an additional haploid set with 16 m and 8 sm chromosomes could be identified. The NOR-bearing chromosomes of te traploids include at least one large st and one large m. Those two haploid chromosome sets could not be assigned to any of the species of the genus Co bitis karyotyped so far.