Taxonomy of Genus Puntius (Hamilton, 1822) and Pethia (Hamilton, 1822) in the Lakes of Pokhara Valley

Abstract

This study investigates the taxonomy, morphology, and morphometric characteristics of two Puntius species (Puntius sophore and Puntius chola) and one Pethia species (Pethia conchonius) inhabiting the three lakes of Pokhara Valley, namely, Phewa, Begnas and Rupa lake. A total of 65 specimens were analyzed for 38 morphometric characters and 12 meristic counts, with their morphological features compared to earlier descriptions. Morphometric analysis revealed significant interspecies differences: P. chola exhibited the largest total length (TL) at 8.32 cm, followed by P. sophore (6.17 cm) and P. conchonius (4.97 cm). Similarly, P. chola had the greatest standard length (SL) at 6.46 cm, while P. conchonius was the smallest at 3.90 cm. Body depth (BD) was highest in P. chola (2.31 cm), followed by P. sophore (1.71 cm) and P. conchonius (1.31 cm), reflecting potential ecological niche differentiation. Meristic traits further supported species differentiation, with P. chola displaying larger fin measurements across dorsal, pectoral, pelvic, and anal fins. Statistical analyses, including correlation and regression, revealed varying degrees of predictability in morphometric traits relative to total length (TL) and head length (HL). P. chola exhibited the strongest correlations (e.g., R = 0.83 for SL-TL), while P. sophore and P. conchonius showed moderate to weak correlations (R values ranging from -0.62 to 0.56), suggesting environmental or genetic influences on variability. The PCA and truss analyses reveal clear morphological differentiation among the three species. Puntius chola is distinctly separated while P. sophore and P. conchonius show closer similarity. PCA analysis revealed that PC1 accounted for 98.7% of the total variation, clearly separating P. chola (score: 6.65) from P. sophore (–1.23) and P. conchonius (–5.41). PC2 explained only 1.3%, reflecting minor differences, with P. conchonius at 0.52, P. chola at 0.28, and P. sophore at –0.79. PCA plot shows AFL and PFL strongly influenced by PC1, aligning with P. chola’s distinct score, while DFH and DPA contributed negatively, corresponding to the lower scores of P. sophore and P. conchonius. The dendrogram based on truss analysis showed that P. sophore and P. conchonius clustered closely, while P. chola branched off at a much higher distance, confirming its distinct morphology. In the dendrogram, the vertical height represents the level of difference between the species’ body shapes. These findings confirm the effectiveness of multivariate morphometric methods in species discrimination. This study provides the foundational data crucial for the future investigations concerning taxonomy of the fish species found in lakes of Pokhara valley.