UTTAR PRADESH JOURNAL OF ZOOLOGY

Cytogenetic characterisation of native cyprinid fishes is important for understanding chromosomal variation and supporting taxonomic comparisons within biodiversity-rich freshwater systems. This study aimed to determine and compare the diploid chromosome number, karyotype formula, fundamental arm number, and chromosome morphometry of Puntius sophore and Plesiopuntius bimaculatus collected from the Gadana River in the Western Ghats. The karyotypic and cytological characteristics of these two species were examined using Giemsa-stained metaphase chromosome preparations. Kidney and spleen tissues were processed following acclimatisation, phytohaemagglutinin stimulation, colchicine treatment, hypotonic exposure, fixation, and air-drying. Twenty metaphase spreads were analysed for each species. Both species exhibited a modal diploid chromosome number of 2n = 50, but their karyotype composition and fundamental arm numbers differed. Puntius sophore possessed the karyotype formula 8m + 2sm + 26st + 14t, with FN = 60, whereas Plesiopuntius bimaculatus showed 28m + 22t, with FN = 78. Chromosome lengths ranged from 0.43 to 1.08 µm in P. sophore and from 0.43 to 0.89 µm in P. bimaculatus. No visibly differentiated sex chromosomes were detected in the metaphase preparations. The shared diploid number, together with differences in chromosome morphology and arm number, indicates karyomorphological differentiation within a conserved cyprinid chromosome-number framework. These locality-specific data provide a cytogenetic baseline for comparative studies of the two species in the Western Ghats. Broader population sampling and the application of chromosome banding, fluorescence in situ hybridisation, and molecular cytogenetic markers are required to determine whether the observed differences are population-level variants or stable species-specific characteristics.