Multivariate morphometric differentiation of Macrobrachium species (Crustacea: Palaemonidae) along the northern rivers of Bangladesh

Abstract

Understanding interspecific morphometric variation is a prerequisite of species identification, evolutionary and taxonomic studies. The external features (i.e. morphometric and ratios) of five Macrobrachium species viz., Macrobrachium rosenbergii, M. lanchesteri, M. dolichodactylus, M. idella and M. lamarrei from three rivers in northern Bangladesh, were used to analyze interspecific morphometric variation. Macrobrachium samples were collected from Jamuneshwari river, Tangon river and Atrai river. Morphometric and ratios data were subjected to univariate ANOVA test. To assess variations among the species, a principal component analysis (PCA) and canonical variate analysis (CVA) were performed. Four PCA explained 95.31% of the variation in morphometric and ratios data. Four CVA were correctly classified as 46.53%, 30.02%, 18.10% and 5.35% respectively using morphometric and ratios data. Morphometric and ratio results from PCA formed a compact cluster among species while in CVA showed that species were completely formed a separate cluster. A dendrogram independently developed based on phenotypic traits among the individuals of the five Macrobrachium species confirmed the presence of phenotypic differentiation. The baseline evidence ensuing from the current study would be advantageous for geometric morphometric, genetic investigations and further in situ conservation of Macrobrachium species in Bangladesh.

Morphological Diversity of Different Male Morphotypes of Giant Freshwater Prawn Macrobrachium rosenbergii (De Man, 1879)

“…Morphological variations of the major chelipeds have been established in many commercial crustacean species, mainly in males (e.g., [46][47][48]). So far, the few identified morphotypes out of about 250 species of the Macrobrachium genus all differ in cheliped morphology [5,7,9,10,49]. According to these authors, chelipeds are one of the morphometric traits that can be highly varied among the morphotypes of Macrobrachium.…”

“…Differential cheliped patterns, particularly in the propodus and dactylus, have been used to distinguish male morphotypes of Macrobrachium [42]. According to Hoshan et al (2022) [49], small differences in cheliped measurements can reveal the dominant individuals in a population, that is, individuals of the higher cast become dominant because they have more developed chelipeds, regardless of their body size. Studies on various species of Macrobrachium emphasized the importance of chelipeds for predation, aggression, mating, and protection of females by males [10,13,50].…”