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The science of cytogenetics deals with the structure and behavior of chromosomes during the mitotic and meiotic division of cells. Chromosomal studies have received significant attention over the past few years, especially in the disciplines of Karyology and Cytogenetics. Animal species provide a vital contribution to the knowledge of chromosome evolution. The species studied during the present investigation possessed 2n = 74 chromosomes and the karyotypic formula of Himalayapotamon emphysetumwas found to be 2n = 46 m + 10sm + 6st + 12t. Meiosis was observed to be normal and thirty-seven bivalents in the form of rings were observed during diakinesis. The individual chromosomes in the Karyotype were identified by using NOR-banding method. The data generated during the present study adds great knowledge to the karyosystematics of the crab species and will help understand interrelationships among the different crab species and also aids in undertaking hybridization programmes. Data related to the karyotypic features is considered a pre-requisite for genomic studies.

The genus Macrobrachium, despite having immense nutritional, medical, and ornamental importance, is least explored cytogenetically. One of its species M. kistnensefrom J&K is an eligible candidate for commercial culturing and can enhance the dietary protein content and economic standard of local inhabitants. There is no previous record of chromosome number and karyotype of this species. Therefore, in the present study, the diploid number and karyotypic characteristics of M. kistnensewere worked out by using conventional Giemsa staining and chromosome banding techniques. The diploid chromosome number was found to be 2n= 74 with karyotypic formula (54m + 14sm + 4st + 2t). The characteristic banding patterns were also obtained after Ag- NOR and G-banding. The present study will aid to solve taxonomic ambiguities within the family Palaemonidae and also in general understanding of the course of evolution in order Decapoda.