Morpho-genetic characterization of morphotypes of the giant freshwater prawn, Macrobrachium rosenbergii

Different morphotypes of Macrobrachium rosenbergii show variations in growth. Theobjective of the study is to characterize the morphological and genetic variations in M.rosenbergii male and female morphotypes. Juveniles of M. rosenbergii (average body wt.5.33±0.72 g) were stocked in an earthen pond at a stocking density of 20,000 per hectare andreared for five months using shrimp quality feed. After harvesting, males were characterized intothree morphotypes such as blue- and orange-clawed males (BC and OC, respectively) and smallmales (SM) based on color and claw length. Here, morphometric characteristics of the BCmorphotype demonstrated significantly higher (p<0.05) values followed by OC, SM, andfemales. Likely, the proportion of CL and BL were found to be highest in the OC morphotype(1.25±0.01) followed by BC (1.16±0.10), SM (0.84±0.10), and female morphotypes(0.64±0.16). For the genetic variation study, four allozyme enzymes were screened that wereencoded by six loci (Ldh-1*, Mdh-1*, Mdh-1*, Pgm*, Gpi-2*, and Gpi-2*). Two loci, Gpi-1*and Pgm* showed polymorphism (p<0.05) in all morphotypes. The observed (Ho) and expected(He) heterozygosities were higher in the BC morphotype followed by OC, female and SM. In theUPGMA dendrogram, the BC morphotype made a one cluster and was differentiated from othermorphotypes by the genetic distance D=0.0047. The results suggest that considerablemorphogenetic variations existed in BC, OC and SM morphotypes even though they weresiblings.