Karyological studies on the freshwater prawn Macrobrachium rosenbergii

A cytogenetic study was conducted in the freshwater prawn, Macrobrachium rosenbergii, by preparing metaphase chromosome spreads from the tissue of the antennal gland and testis. Chromosomal analysis of the antennal gland in males revealed a modal diploid chromosome number of 2n = 118. This was confirmed by the modal haploid chromosome number of n = 59 for the testis. A large peak in the female histogram indicated a modal diploid chromosome number of 2n = 118. However, a certain number of cells of chromosome number 117 and a second smaller peak of chromosome number 111 were also observed. Thus, it was not possible to establish conclusively the diploid chromosome number in females. The karyotype observed in mitotic metaphase chromosomes from the antennal gland probably consisted of 45 meta- and submetacentric, and 14 subtelo- and acrocentric pairs. Sex chromosomes were cytologically indistinguishable.