Cytogenetics of Eupemphix nattereri Steindachner, 1863 (Anura: Leiuperidae) and karyotypic similarity with species of related genera: taxonomic implications (In English)

摘要

Eupemphix nattereri Steindachner, 1863 from three localities in Brazil showed 2n=22 karyotype, with metacentric or submetacentric chromosomes and one telocentric pair 11. The specimens have a single pair of Ag-NOR, at the distal region of the long arms of chromosomes 11, although Ag-positive labeling was frequently observed in the proximal region of these chromosomes. The true Ag-NOR was confirmed by FISH with an rDNA probe, which never hybridized in any other chromosome site. C banding pattern is predominantly centromeric, with some interstitial or telomeric bands. Chromosomes 8 presented either gain or loss of interstitial heterochromatin, leading to size variation between the homologs in some specimens. Since the heteromorphism occurred in specimens from the three localities and in both male and female collected in one of them, at present, the possibility of geographical karyotypic variation and of cytologically differentiated sex chromosomes was ruled out, due to the small sample size. An increased amount in the centromeric heterochromatin of the chromosome 11 was seen, but only in specimens from one of the localities. CMA₃ staining revealed some GC-rich repetitive regions, whereas with DAPI no particular bright AT-rich site was detected. BrdU replication banding was obtained for the first time, but karyotypic comparisons with leiuperids of related genera were based on standard stained chromosomes. The karyotype of Eupemphix nattereri is indistinguishable of those presented by the representatives of Physalaemus signifer group analyzed so far. Moreover, the species is karyologically very close to the species of Pleurodema Tschudi, 1838, so that our cytogenetic data agree with the proposal based on morphological characters of including Eupemphix nattereri , Pleurodema diplolister (Peters, 1870) and P . brachyops (Cope, 1869) in the same clade [ Acta Zoologica Sinica 53( 2 ): 285 –293 , 200 7 ] .