PHYLOGENETIC STUDY OF SPERATA SP. FOUND IN SYLHET SADAR, SYLHET

Abstract

The present study was conducted in Kazir bazar fish market, Lal Bazar (Bandor) fish market and Majortila fish market, Sylhet for a period of three months from July to September 2014. Three biometric, 24 morphometric and 7 meristic measurements were investigated for 150 species of Sperata genus. Among them 94 species of S. seenghala and S. aor were identified. Mean total lengths of S. seenghala and S. aor were measured 399.32±53.8 and 373.9±98.1 mm respectively, fork length was recorded 340.27±29.9 and 302.03±56.6 mm and the standard lengths of the sampled fishes were 311.85±33.9 and 282.02±55.1 mm respectively. Among the two species of Sperata discrimination in color was observed. Clear discrimination was observed in the shape of the mouths between the species. The mouth of S. seenghala is of rectangular shape, whereas, S. aor is of round shape. The mean snout length of S. seenghala and S. aor found to be 20.34±4.50 and 21.437±7.62 mm respectively. The head length in S. seenghala was higher than both S. aor. The genus Sperata is characterized by 4 pairs of barbels. In case of S. aor it was always seen that the maxillary barbel touches the last portion of adipose fin. But in case of S. seenghala it is too short and does not touches the adipose fin. The adipose fin was encountered to be continuous, large and round shape in S. aor. The shape of 2 nd occipital process is conical in S. seenghala, oval in S. aor and the mean length was 28.3±3.27 and 24.68±5.32 mm and mean diameter was 6.63±1.16 and 7.87±3.63 mm respectively. Among the 24 assessed morphometric parameters only occipital (2nd) diameters, distance between occipitals, length of intestine, anal fin depth, 1 occipital length and 2 st nd occipital length were found to be significantly different among the species (<0.05).Among the meristic characters accounted, only few exceptions were found among the species of Sperata. In case of S. seenghala and S. aor no. of branchiostegal rays counted to be 11 and 11 respectively. On the other hand, variation was also observed in no. of pectoral fin rays which is 1/9 for S. seenghala and 1/10 for S. aor. But rest of the meristic counts found to be similar between the species. As the biometric, morphometric and meristic characters revealed distinguished discrepancy between the species. Finally, it seems from the study that at least two species of Sperata are available in Sylhet Sadar, Sylhet.