Morphological traits Characterization of Macrobrachium macrobrachion (Herklots, 1851) and Macrobrachium vollenhovenii (Herklots, 1857) from Osun River, Southwestern, Nigeria

Document Type: Primary Research paper

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Abstract

Morphological traits used in taxonomic separation of M. macrobrachion and M. vollenhovenii into two distinct species were reviewed. Observations from non-parametric traits revealed that M. macrobrachion exhibited absence of spinules on the palm; short and scanty pubescence on telson and uropod; a region of rostral spines discontinuity and presence of apical tooth on the dorsal part of rostrum which distinguished it from M. vollenhovenii. Measurements of parametric traits showed that there were no significant variations (p>0.05) in the mean total lengths, carapace lengths and rostral lengths between male to male and female to female specimens of the two prawns. Also, no significant variation (p>0.05) existed in their mean body weights, although specimens of M. vollenhovenii appeared more robust in body shape. Mean chela lengths (right and left) were higher for M. macrobrachion than for M. vollenhovenii. Meristic count of dorsal spines on rostrum ranged from 8-15 and 8-16 while that of ventral spines ranged from 3-7 and 3-8 for M. macrobrachion and M. vollenhovenii respectively. The results obtained in this study revealed that these prawns are easily separable based on their morphological traits. However, further study is recommended for their genetic characterization to validate their true existence as separate species.

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