Morphologic and phylogenetic investigations revealed size-divergent clades in chelae morphotypes of freshwater prawn Macrobrachium vollenhovenii Herklots (Decapoda: Palaemonidae) in a lake and river system of Southwest Nigeria

Abstract Background The freshwater prawn Macrobrachium vollenhovenii is one of the largest Macrobrachium species, a biological agent against human schistosomiasis, and a cheap protein source in riverine communities in West Africa. However, its aquaculture development for sustainable utilization is challenged by cryptic identity amidst the presence of morphotypes of unknown size and genetic relatedness. This study aimed to investigate the maximum sizes and evolutionary links of chelae morphotypes in M. vollenhovenii for precise identification and utilization in a 3 × 2 randomized block experimental design. Ninety biggest encountered samples of M. vollenhovenii chelae morphotypes—those possessing equal left and right side chelae, longer left chelae, and shorter left chelae—were obtained from fisherfolks’ catches at each of Asejire Lake and Ogun River during peak seasons (July–September) bimonthly field survey, representing EAAL, LLAL, SLAL—GAALs, and EAOR, LLOR, SLOR—GAORs. These were analyzed for differences (p