Karyotype Analysis of the New Catfish Mystus ngasep (Siluriformes: Bagridae) from Manipur, India

Abstract

Karyotypic and cytogenetic characteristics of catfish Mystus ngasep, a new species of bagrid catfish described from the Northeast India, Manipur was studied for the first time by examining 200 metaphase spreads chromosome from the kidney cells of 25 healthy specimens. The diploid chromosome number of this species was 2n=56 and the total fundamental arm number was determined as NF=90. The karyotype consisted of 12 Metacentric (m), 22 Submetacentric (Sm), 8 Subtelocentric (St) and 14 Telocentric (t) chromosomes. The chromosome formula can be represented as 2n= 12m + 22Sm + 8St + 14t. No heteromorphic sex chromosomes were cytologically detected. Chromosome number, formula and karyotype of Mystus ngasep differentiate it from other closely related species. The largest chromosome in this species is a pair of metacentric chromosomes and the present study is the first report on the karyology of this particular species which will pave the way for the future studies on this line of karyology for this genus. Thus, this study is of importance in the analysis of karyotypic evolutionary trends, classification and taxonomy of the genus Mystus and better understanding of the karyotype diversity and chromosome evolution processes.